Aneurysmal Bone Cyst
Introduction and Definition: This lesion is not a true neoplasm, but rather is thought to be a reactive lesion that may be caused by a local arteriovenous malformation or vascular injury. The true cause is unknown. There is a definite relationship to local trauma in some cases, and other cases are associated with another tumor such as osteoblastoma, chondroblastoma, fibrous dysplasia, or other. A large proportion of these lesion appear to arise de novo without any definite traumatic or neoplastic cause. Incidence and Demographics: ABC is found most commonly during the second decade and the ratio of female to male is 2:1. ABC's can be found in any bone in the body. The most common location is the metaphysis of the lower extremity long bones, more so than the upper extremity. The vertebral bodies or arches of the spine also may be involved. Approximately one-half of lesions in flat bones occur in the pelvis. Symptoms and Presentation: Gradually increasing pain, a mass, or with a pathological fracture through the lesion. Rapid increase is lesion size has been reported in a few cases. X-Ray Appearance and Advanced Imaging Findings: On plain film, an ABC is normally placed eccentrically in the metaphysis and appears osteolytic. The periosteum is elevated and the cortex is eroded to a thin margin.The expansile nature of the lesion is often reflected by a "blow-out" or "soap bubble" appearance. CT scan can also help delineate lesions in the pelvis or spine where plain film imaging may be inadequate. CT scan and MRI can narrow the differential diagnosis of ABC by demonstrating multiple fluid-fluid levels within the cystic spaces. MRI is useful to confirm the multiple fluid-fluid levels and the non-homogeneity of the lesion. ABC appears on both T1 and T2 MRI with a low signal rim encircling the cystic lesion. A careful search for radiological signs of the precursor lesion, if any, is recommended. Some of these precursor lesions may have a flocculent chondroid matrix that may be a clue to their pathogenesis. Laboratory Findings: No relevant findings Differential Diagnosis: Giant cell tumor, UBC, Telangectatic osteosarcoma Preferred Biopsy Technique: Incisional / combined with curettage if certainty of diagnosis is high Histopathology findings: On gross examination, an ABC is like a blood filled sponge with a thin periosteal membrane. Soft, fibrous walls separate spaces filled with friable blood clot. Microscopically, the ABC has cystic spaces filled with blood. The fibrous septa have immature woven bone trabeculae as well as I macrophages filled with hemosiderin, fibroblasts, capillaries and giant cells. The treatment approach will vary depending of the location and aggressiveness of the lesion. A slow growing, indolent ABC has been observed to regress spontaneously. Selective embolectomy of nutrient vessels and percutaneous injection of a fibrosing agent are newer treatment modalities. Percutaneous injection of methylmethacrylate was used successfully by Herve Deramond for an aggressive ABC lesion in the second cervical vertebra. Treatment Options for this Tumor: Curettage is normally used. Large lesions may require other treatments, such as embolization. The cyst can be packed with bone chips or polymethylmethacrylate cement. Bone fragility must be addressed with plates, screws, or rods as indicated. Percutaneous transvascular treatments have be used with good results, and are especially useful in difficult to access lesions of the spine and skull base. Preferred Margin for this Tumor: Intralesional Outcomes of Treatment and Prognosis: Recurrence is seen in approximately 20% of cases and is more common in younger children. Special and Unusual Features: One theory of the etiology of primary ABCs is that these lesions are secondary to increased venous pressure that leads to hemorrhage which causes osteolysis. This osteolysis can in turn promote more hemorrhage causing amplification of the cyst. Another theory is that these lesions do not arise de novo by rather develop secondarily within another primary tumor such as osteoblastoma, and subsequently enlarge and destroy all or most of the primary tumor.
Chondroblastoma
Introduction and Definition: About 12% of all chondroblastomas occur in the bones of the foot. Chondroblastoma in the foot most commonly occurs in subchondral areas of the talus and calcaneus as well as the calcaneal apophysis. Chondroblastoma can behave aggressively and invade soft tissue. Benign pulmonary metastases have been observed. Incidence and Demographics: Males are affected 6 times as commonly as females. The average age at presentation around 25 years, significantly older than the average age in other parts of the skeleton. Symptoms and Presentation: Patients complaint of pain and swelling or a mass near the joint. The pain can be severe. The nearby joint may be locally inflamed. X-Ray Appearance and Advanced Imaging Findings: Radiographically, the lesion is located in the exclusively in the epiphysisis, although in the small bones of the foot the location of the epiphysis may not be obvious. The lesions appear well-defined, expansile, and lucent, and there may be stippled calcification or there may be no matrix mineralization. The tumor is adjacent to an articular surface or an apophysis. There is a lobular appearance. CT scan is useful for defining the relationship of the tumor to the joint, the integrity of the underlying bone, and to identify intralesional calcifications. MRI scans show the very high signal intensity on T2 weighted scans that is characteristic of cartilage lesions. Bone scan shows avid tracer uptake in the lesion. Laboratory Findings: No relevant findings Differential Diagnosis: Enchondroma, Central Chondrosarcoma and Aneurysmal Bone Cyst Preferred Biopsy Technique: Incisional, may be combined with excision in selected cases Histopathology findings: On gross examination, a chondroblastoma has a lobulated, round form and is made up of friable, soft, grayish pink tissue that may be gritty. If present, the cystic fluid is rust or straw-colored. Chondroblastoma is made up of uniform, polygonal cells that are closely packed. These primitive cells are derived from the epiphyseal cartilage plate and have abundant cytoplasm. These cells have oval shaped nuclei with a prominent groove which has been likened to a coffee bean. There is little mitotic activity. A scant chondroid matrix may be superimposed by a pericellular deposit of calcification that appears like "chicken-wire". The rapid proliferation of immature chondrocytes does not create lacunae or formal cartilage matrix. Giant cells are often present. Treatment Options for this Tumor: Treatment of the primary lesion consists of complete curettage and bone grafting. Extending the zone of the curettage by removing two or 3 additional millimeters of bone using a mechanical bur, or by using phenol or liquid nitrogen placed in the tumor cavity have been proposed as in method to reduce the risk of local recurrence. Preferred Margin for this Tumor: Intralesional Outcomes of Treatment and Prognosis: In chondromblastoma of the foot and ankle, recurrence is common, and outcomes are generally worse than in other locations in the skeleton. The risk of recurrence appears to be highest for lesions located only in the epiphysis, as opposed to lesions in the apophysis or those that extend into the metaphysis or diaphysis. Recurrence is not definitely related to patient age, sex or demographic data. Recurrent lesions should be treated with repeat curettage. If a recurrent lesion is located in a readily reconstructable location, marginal resection with structural allograft or autograft reconstruction is preferable. Recurrence and severe destruction of bone integrity may necessitate ankle arthrodesis or en-bloc resection with associated functional loss. Patients with recurrent lesions should have follow-up CT scans of the chest to detect pulmonary nodules. Pulmonary nodules should be excised. Suggested Reading and Reference: Fink BR, Temple HT, Chiricosta FM, Mizel MS, Murphey MD. Foot Ankle Int. 1997 Apr;18(4):236-42. Chondroblastoma of the foot.
Chondrosarcoma
Introduction and Definition: Chondrosarcoma is the most common malignant bone tumor in the foot in some reported series. Patients with multiple cartilage lesions, such as Ollier's disease, or multiple enchondromas are at increased risk. This tumor has several subtypes, including clear cell chondrosarcoma, and mesenchymal chondrosarcoma, which can occur in bone (images 1, 2, 3, 4) in the soft tissues (image 5), where it presents as as an innocent bump. Most chondrosarcomas are low grade, but dedifferentiated chondrosarcoma can occur in the setting of a longstanding benign cartilage lesion such as enchondroma. Incidence and Demographics: The peak age of presentation is in the 50's and 60's and has a male to female ratio of 1.5 to 1. It is most common in the femur, humerus, ribs and on the surface of the pelvis. Patients with Ollier's disease (multiple enchondromatosis) or Maffucci's syndrome (multiple enchondromas and hemangiomas) are at much higher risk of chondrosarcoma than the normal population and often present in the third and fourth decade. Symptoms and Presentation: The presentation of chondrosarcoma depends on the grade of the tumor. A high-grade, fast growing tumor can present with excruciating pain. A low grade, more indolent tumor is more likely to present as an older patient complaining of hip pain and swelling. Pelvic tumors present with urinary frequency or obstruction or may masquerade as "groin muscle pulls" The lesion presents as a slow growing mass with mild pain. X-Ray Appearance and Advanced Imaging Findings: On plain radiographs, chondrosarcoma is a fusiform, lytic, lucent defect with scalloping of the inner cortex (which may demonstrate ring and arc formations ) and periosteal reaction. Extension into the soft tissue may be present (malignant behavior) as well as punctate or stippled calcification of the cartilage matrix. CT is helpful in defining the integrity of the cortex and distribution of calcification. MRI is invaluable in surgical planning as it demonstrates the intraosseus and soft tissue involvement of the tumor. MRI is also helpful in evaluating possible malignant degeneration of osteochondromas by allowing accurate measurements of the cartilage cap which should be less than 2 cm thick. MRI shows high signal intensity on T2 sequences, and low intensity signal on T1 sequences. Calcification within the mass, if it occurs, will appear as very low signal areas. Differential Diagnosis: Osteosarcoma, benign cartilage lesions Preferred Biopsy Technique: Incisional Preferred Margin for this Tumor: Wide
Histopathology findings: On gross examination, chondrosarcoma is a grayish-white, lobulated mass. It may have focal calcification, mucoid I degeneration, or necrosis.Histologically, chondrosarcoma is differentiated from benign cartilage growths by enlarged plump nuclei, multiple cells per lacunae, binucleated cells, and hyperchromic nuclear pleomorphism. Chondrosarcoma is graded from 1 (low) to 3 (high). Low grade chondrosarcoma is very close in appearance to enchondromas and osteochondromas and has occasional binucleated cells. High grade chondrosarcomas have increased cellularity, atypia and mitoses. There is an inverse relationship between histologic grade and prognosis with higher grades having a worse prognosis and early metastases. Treatment Options for this Tumor: Treatment for low grade chondrosarcoma may include curettage or marginal excision. Intermediate and high grade lesions should be excised with a wide margin. Clear margins are essential, because no truly effective adjuvant therapy exists. Chemotherapy and radiotherapy are not effective and are normally not used for lesions in the foot. Rather, complete removal with a wide margin is the correct treatment. Amputation of the affected part is employed if necessary to achieve a wide margin. Incompletely excised lesions should be referred to a musculoskeletal oncologist for re-resection. Special and Unusual Features: here are three additional types of chondrosarcoma. Mesenchymal chondrosarcoma is a rare variant with a bimorphic histologic picture of low grade cartilaginous cells and hypercellular small, uniform, and undifferentiated cells that resemble Ewing's sarcoma. Mesenchymal chondrosarcoma has a predilection for the spine, ribs and jaw and it presents in the third decade. It is more common in females and can grow exceptionally large. It is very likely to metastasize to lungs, Iymph nodes and other bones. Clear cell chondrosarcoma is a malignant cartilage tumor that may be the adult variant of chondroblastoma. It is a rare, low-grade tumor with an improved prognosis over other chondrosarcomas. Likechondroblastoma, it is found in the epiphysis of the femur and humerus. Histologically, soft tissue invasion is rare. Clear cell chondrosarcoma has clear cells with vacuolated cytoplasm. The cartilage matrix has significantly calcified trabeculae and giant cells. Dedifferentiated chondrosarcoma is the most malignant form of chondrosarcoma. This tumor is a mix of low grade chondrosarcoma and high grade spindle cell sarcoma where the spindle cells are no longer identifiable as having a cartilage origin. The dedifferentiated portion of the lesion may have histological features of malignant fibrous histiocytoma, osteosarcoma, or undifferentiated sarcoma. This biphasic quality is evident on x-ray with areas of endosteal scalloping and cortical thickening are contrasted with areas of cortical destruction and soft tissue invasion. Dedifferentiated chondrosarcoma has a 5 year survival of 10%.
Chondromyxoid Fibroma
Introduction and Definition: This rare benign tumor has a striking predilection for the bones of the tibia and the foot. About one quarter of all of these tumors involve the foot, with the metatarsals the most common location. Incidence and Demographics: Most patients are younger than 30. It is more common in males, typically in the second or third decade of life. Symptoms and Presentation: Patients present with pain and a slow growing mass. X-Ray Appearance and Advanced Imaging Findings: Radiological findings demonstrate an eccentrically placed Iytic lesion with well defined margins in the metaphysis of the lower extremity. The lesion usually has a sclerotic margin of bone and a lobulated contour. Ridges and grooves that appear in the margins secondary to scalloping falsely appear to be trabeculae. CT helps define cortical integrity and confirms that there is no mineralization of the matrix, unlike other cartilage tumors. CMF has the same appearance on MRI as other cartilage tumors which is decreased signal on T 1 weighted images and increased signal on T2 weighted images. MRI is helpful in preoperative planning and staging. CMF resembles fibrocartilage grossly. It has a sharp border often with an outer surface of thin bone or periosteum. The glistening grayish white lesion is firm and lobulated. It may also have small cystic foci or areas of hemorrhage. Laboratory Findings: No relevant findings Differential Diagnosis: The radiologic differential diagnosis includes giant cell tumor, aneurysmal bone cyst, juxtacortical chondroma, unicameral bone cyst, chondroblastoma and fibrous dysplasia Preferred Biopsy Technique: Careful biopsy and evaluation by an experienced pathologist are necessary to distinguish this tumor from similar aggressive or malignant lesions. Curettage may be adequate, but may result in local recurrence in as many as a quarter of patients. Histopathology findings: Histologically, CMF appears very similar to chondrosarcoma. They are so close in histology that often radiology helps to make the final diagnosis. The predominant features of CMF are the zonal architecture and lobular pattern. Nodules of cartilage are found in between fibromyxoid areas. In some fields the loose myxoid dominates and in other the dense chondroid dominates. The chondrocytes are plump to spindly in shape and have indistinct cell borders in sparsely cellular lobules of myxoid or chondroid matrix. There are also more cellular zones of the tumor with some giant cells at the edges. The sharp borders of each lobule and the lesion itself help to differentiate it from chondrosarcoma. Treatment Options for this Tumor: Marginal or wide excision and substitution of the involved bone with a structural bone graft is usually curative. Outcomes of Treatment and Prognosis: Unlike giant cell tumor, this tumor has a propensity to recur due to seeding of the soft tissues during curettage. Local recurrence can be treated with meticulous repeat curettage and excision of the entire soft tissue mass. Marginal or wide excision and substitution of the involved bone with a structural bone graft is usually curative.
CASE: Chondromyxoid Fibroma
A 13-year-old boy presents to the orthopedic outpatient department (OPD) with a 1.5-year history of mild, recurrent pain in his left lower leg with recent exacerbation of the pain after a trivial trauma during outdoor activity. He has no history of any systemic symptoms, such as fever, or any other significant past medical history. There is no significant family medical history. The patient is a well-built, athletic-appearing boy. His blood pressure is 116/78 mm Hg, his pulse rate is 68 bpm, and his body temperature is measured at 98.2°F (36.8°C) during his first visit to the OPD. Examination of the leg reveals severe localized tenderness over the lower left tibial prominence, with softtissue swelling and edema. According to the patient, he has been feeling mild fullness over the left medial malleolus for more than 1 year, without it causing much pain. The overlying skin shows mild reddening as well as increased local temperature. The cardiovascular, respiratory, and gastrointestinal organs examined clinically are within normal physiologic limits. The hematologic and biochemical parameters examined are within normal physiologic limits. The erythrocyte sedimentation rate and C-reactive protein levels are also within normal physiologic limits. The hematologic examination shows a hemoglobin level of 11 g/dL, total leukocyte count of 13,000 x 103/μL and a platelet count of 180 x 103/μL. An anteroposterior chest x-ray does not show any localized lesions in the lungs. No lymphadenopathy is detected. Anteroposterior- and lateral-view x-rays of the lower left end of the tibia show an eccentrically located, well-demarcated, lytic, bubbly, lobulated lesion in the metaphyseal region (Figure 1). A periosteal reaction is not seen. Focal epiphyseal extension is also noted (Figure 2). A subtle fracture is identified at the lateral margin of the lower tibia (Figures 1 and 2). Axial T2-weighted MRI also shows a hyperintense solid lobulated growth (Figure 3). A biopsy is performed, but unfortunately the yield is scant and is comprised only of fibrous tissue and traces of cartilaginous material. Curetting and bone grafting is performed, with the corresponding histopathologic examination demonstrating a characteristic biphasic lesion (Figure 4). A frozen section prepared from the curettage shows a possible benign cartilaginous tumor.
The x-rays and MRI of the left lower tibia demonstrated features of a chondromyxoid fibroma (CMF) with fracture of the lower end of the tibia. Grossly, the specimen demonstrated multiple grey-white fragments, with focally identifiable firm periosteal bone attached over the fragments. The cut surface of the fragments showed a shiny myxoid appearance with intervening firm grey-white areas. Histopathologic examination showed a lobulated lesion. The lobules of chondromyxoid materials were separated by thin cellular septae comprised of innocuous-looking spindle cells with interspersed small vessels and few osteoclastic giant cells. The chondromyxoid component showed varying cellularity. The periphery of the lobules was more cellular in appearance, and the cells were predominantly spindle in shape. In the center, the cells had a moderate amount of eosinophilic cytoplasm, while a few others were stellate-shaped. Chondrocytes were also identified. There was no evidence of multinucleation within the lacunae or significant nuclear pleomorphism. The spindle-cell component also did not show any pleomorphism or mitotic activity (Figure 4). These features, correlated with the radiologic findings, were indicative of CMF. CMF is a benign tumor of bone that was first described by Jaffe and Lichenstein in 1948.[1,2] This lesion accounts for 1% of all bone tumors and 2% of all benign bone tumors.[3] It is most commonly found in the long tubular bones, especially the tibia and femur near the knee joint; however, the overall most common site is the proximal tibia, which is affected in 30% of cases. Approximately 25% of cases occur in the flat bones.[3,4] The small bones of the lower limbs may also be affected. The skull, spine, and bones of the upper extremity are relatively uncommon sites for this lesion. Patients with this condition range from 3 to 70 years of age; most cases, however, are seen in patients between the ages of 10 and 30 years. A male predominance has been described (male-to-female ratio, 2:1).[3,5] The most common presenting symptoms are pain and swelling, which are noted in 85% and 65% of cases, respectively; the third most common symptom is restriction in joint movement. The pain is usually mild, transient, and of long duration.[6] Approximately 15% of cases are discovered incidentally on radiologic examination. Pathologic fracture may occur in 5% of cases, causing significant morbidity. Plain x-rays are very useful when this lesion is suspected; however, histopathologic examination is mandatory for confirmation of the diagnosis. Bubbly lesions are typical in the metaphysis, and when seen, a differential diagnosis of giant cell tumor, aneurysmal bone cyst, and CMF should always be kept in mind. The possibility of an osteosarcoma should also be considered. The bubbly pattern is usually caused by ridging or endosteal scalloping of the surrounding host bone. Histologically, the possibility of a low-grade chondrosarcoma should also be carefully ruled out. Because of the nodular growth pattern of any cartilaginous tumor, the histologic diagnosis is primarily based on the extent of cellularity and the cytologic atypia of the tumor cells. Mild-to-moderate cytologic atypia, however, has also been described in CMF; therefore, the extent of cellularity, multinucleation within the lacunae, and the presence of atypical mitotic activity in the tumor should be relied upon as features to rule out chondrosarcoma. In this context, it is also important to remember that the periphery of the nodules in CMF show marked cellularity and should prompt histopathologists to concentrate on the center of the lobules when assessing the criteria of cellularity. CMF, like osteosarcoma, shows erosion of cortical bone with soft tissue infiltration. Osteoid production by the tumor cells is also characteristic of this lesion. Radiologic correlation is mandatory because CMFs are typically bubbly, oval in shape, and have a long axis parallel to that of the long bone. Extension into diaphysis or epiphysis is not uncommon.[5,7] Unlike other cartilaginous tumors, calcification is less frequent and the margins are typically scalloped. An MRI scan may help to resolve minute details, such as soft tissue extension. T2-weighted MRI will show a hyperintense, homogeneous lesion (Figure 3). CT scans may help to identify any calcifications within the lesion, which are uncommon and occur in about 2% of cases.[5,7] The histogenesis of CMF is uncertain and is a matter of continuing speculation. The cartilaginous origin, as apparent on the morphologic features, has been supported by ultrastructural studies and by immunohistochemical stains for S-100 protein. Because of their occasional immunopositivity for smooth muscle actin and S-100 proteins, possible myofibroblastic, myochondroblastic, and chondrocytic differentiation was suggested.[7] Due to the same reasons, a possible resemblance with chondroblastoma was
cited; however, this finding was not subsequently substantiated by other studies. Others showed osteocalcin reactivity, which is seen in greater than 50% of CMFs, as a cause to support its link with other bone and cartilage tumors, especially chondroblastomas.[7] A study by Romeo and colleagues[8] examined the DNA microarray of CMF and found that the differential expression of adhesion and extracellular matrix molecules, including CD166, versican, perlecan, and Col4A2, may interfere with normal cartilaginous differentiation and lead to the development of CMF. There are some studies indicating a possible cartilaginous derivation by examining the expression of transcription factor SOX9 in the tumor cell nuclei, along with high expression of collagen type II in the cell cytoplasm. A low (< 5%) MIB-1 proliferation index also supports its indolent character. Although many cytogenetic abnormalities have been reported in CMF, t(1;5)(p13;p13) is a novel clonal cytogenetic abnormality in CMF and has diagnostic significance. Other frequent chromosomal abnormalities described are aberrations in chromosomes 2 and 5.[7] The prognosis in cases of CMF is usually excellent, even when there is recurrence.[5] Treatment of the lesion includes curettage or en bloc excision with bone grafting. Radiotherapy is contraindicated because it causes dedifferentiation and malignancy. In cases of multiple recurrence, radiotherapy may be of some help.[9] Recurrence has been reported in 3%-22% of cases, especially within the first 2 years of surgery, but it has been reported 30 years after surgery as well.[10] Recurrence is more frequently seen in patients younger than 15 years of age with a more myxoid tumor with nuclear atypia. Some reports have not found any correlation between the histologic findings and recurrence in CMF. Metastasis has never been reported.[5] All of these facts point to the need for long-term follow-up in these patients.[11] In the patient in this case, curettage of the lesion with bone grafting was performed. Local extension of the lesion into the articular cartilage and the scant yield of the preintervention biopsy dictated the decision to opt for curettage, followed by fracture fixation. Care should be taken to curette the whole lesion when performing this treatment because incomplete curettage is one of the important factors leading to local tumor recurrence. The patient has had 2 monthly follow-up examinations over a period of 8 months, with no recurrence detected.
Jaffe HL, Lichtenstein L. Chondromyxoid fibroma of bone: a distinctive benign tumor likely to be mistaken especially for chondrosarcoma. Arch Pathol (Chic). 1943;19:541-551. 2. Wu CT, Inwards CY, O'Laughlin S, Rock MG, Beabout JW, Unni KK. Chondromyxoid fibroma of bone: a clinicopathologic review of 278 cases. Hum Pathol. 1998;29:438-446. 3. Ostrowski ML, Spjut HJ, Bridge JA. Chondromyxoid fibroma. In: Fletcher CDM, Unni KK, Mertens F, eds. World Health Organization Classification of Tumors. Pathology and Genetics of Tumors of Soft Tissue and Bone. Lyon: IARC Press; 2002:243-245. 4. Desai SS, Jambhekar NA, Samanthray S, Merchant NH, Puri A, Agarwal M. Chondromyxoid fibromas: a study of 10 cases. J Surg Oncol. 2005;89:28-31. 5. Fechner RE, Mills SE. Tumors of bones and joints. In: Atlas of Tumor Pathology. Fascicle 8, 3rd series. Washington, DC: Armed Forces Institute of Pathology; 1993:95-100. 6. Tallini G, Dorfman H, Brys P, et al. Correlation between clinicopathological features and karyotype in 100 cartilaginous and chordoid tumors. A report from the Chromosomes and Morphology (CHAMP) Collaborative Study Group. J Pathol. 2002;196:194-203. 7. Armah HB, McGough RL, Goodman MA, et al. Chondromyxoid fibroma of rib with a novel chromosomal translocation: a report of four additional cases at unusual sites. Diagn Pathol. 2007;2:44. 8. Romeo S, Oosting J, Rozeman LB, et al. The role of noncartilage-specific molecules in differentiation of cartilaginous tumors: lessons from chondroblastoma and chondromyxoid fibroma. Cancer. 2007;110:385394. 9. Baujat B, Attal P, Racy E, et al. Chondromyxoid fibroma of the nasal bone with extension into the frontal and ethmoidal sinuses: report of one case and a review of the literature. Am J Otolaryngol. 2001;22:150153. 10. Danielsen B, Ritzau M, Wenzel A. Recurrence of chondromyxoid fibroma: a case report. Dentomaxillofac Radiol. 1991;20:265-267. 11. Kikuchi F, Dorfman HD, Kane PB. Recurrent chondromyxoid fibroma of the thoracic spine 30 years after primary excision: case report and review of the literature. Inter Int J Surg Pathol. 2001;9:323-329. 1.
Enchondroma
Introduction and Definition: Approximately 8% of these tumors occur in the bones of the foot. Small, peripheral cartilage tumors tend to be benign, where as large central cartilage lesions are more likely to be malignant. Reliable differentiation of benign from malignant cartilage tumors is difficult. Tumors that are larger, tumors located in the hindfoot or midfoot, or new tumors presenting in a patient with a known history of enchondromatosis (Ollier's disease) have an increased risk of malignancy. Incidence and Demographics: The peak age at diagnosisis around the middle of the fourth decade, but the tumor may present as virtually any age Symptoms and Presentation: Patients present with pain during activities or after an injury, but there is rarely any mass palpable on physical examination. For enchondromas in the phalanges, pathological fracture through the lesion will cause the patient to seek medical care. A few patients have multiple enchondromas and warrant special attention and possibly referral to a bone tumor specialist. X-Ray Appearance and Advanced Imaging Findings: Enchondroma usually occurs in the metatarsals or phalanges of the lesser toes. The hindfoot is rarely involved. The lesion is typically a solitary, slightly expansile,lucent lesion with minimal matrix calcification, that may thin, expand, or fracture the nearby cortex. Radiographically, the lesion is expansile and lytic, with a variable amount of matrix mineralization. The matrix has been described as "popcorn" or "stippled". The matrix consists of nodules of cartilage which tend to calcify at the periphery, so that on high quality radiographs "ring and arc" forms are visible. Clear demonstration of these helps confirm the diagnosis so that biopsy is not necessary. Other radiological findings such as the presence or absence of matrix mineralization, amount and extent of cortical thinning or expansion, and findings on technetium bone scans do not seem to be well correlated with the presence or absence of malignancy. Differential Diagnosis: Juxtacortical chondroma, chondromyxoid fibroma. Giant cell tumor may be mistaken for enchondroma, and both can occur in the foot in similar locations. GCT has no matrix calcification and occurs exclusively in the metaphysis and epiphysis adjacent to the growth plate, often extending right up to the joint surface. In small bones that are completely filled with tumor, these lesions may be difficult e to differentiate. The MRI signal patterns are distinct. Treatment is very different so the surgeon should be careful to make an accurate diagnosis. Preferred Biopsy Technique: Open, combined with excision after frozen section Histopathology findings: On gross examination, an enchondroma consists of bluish-gray lobules of fine translucent tissue. The degree of calcification of the lesion determines if the consistency is gritty.Under the microscope, a thin layer of lamellar bone surrounding the cartilage nodules is a positive sign that the lesion is benign. At low power, there are lobules of different sizes. Blood vessels are surrounded by osteoid. Enchondromas have chondrocytes without atypia inside hyaline cartilage. The nuclei are small, round and pyknotic. The cellularity varies between lesions and within the same lesion. Each potential enchondroma needs to be evaluated for cellularity, nuclear atypia, double nucleated chondrocytes and mitotic activity in a viable area without calcifications to distinguish it from low-grade chondrosarcoma. Small peripheral lesions are more likely to be benign than large axial lesions. The pathologic diagnosis is so difficult it always needs to be made in conjunction with the radiologist and the surgeon Treatment Options for this Tumor: Treatment depends on how expansile the lesion has become. Lesions inside the medullary cavity may remain totally latent, are usually asymptomatic, and no treatment other than intermittent radiographic follow-up is indicated. If a medullary enchondroma requires biopsy for some reason, it can be curetted at the same time and the defect filled with an apropriate bone void filler. Extremely expansile lesions may require complete excision and substitution of a structural allograft. In the foot, these lesions can cause cosmetic and functional loss and pathological fracture. Large lesions in the distal phalanges should be considered for partial amputation of the toe, since the functional and cosmetic result of curettage and bone grafting may be unacceptable. Preferred Margin for this Tumor: Intralesional Outcomes of Treatment and Prognosis: Enchondromas recur very rarely following treatment, so that total eradication of the lesion is not necessary, rather the goal should be is restoring appearance and function. Curettage and bone grafting is usually adequate. Special and Unusual Features: Enchondroma may be highly expansile, especially in small bones such as the phalanges, so that the bone may be completely involved, deformed, and even destroyed. This is not considered a sign of malignancy in enchondromas of the foot or hand. This same behavior seen in a long bone such as the femur or humerus would be interpreted as a strong suggestion of malignancy.
Ewing’s Sarcoma
Introduction and Definition: Ewing's sarcoma is a highly malignant tumor that is a type of peripheral primitive neuroectodermal tumor (PNET). Ewing's sarcoma is found in the lower extremity more than the upper extremity, but any long tubular bone may be affected. The most common sites are the metaphysis and diaphysis of the femur followed by the tibia and humerus. Ewing's sarcoma occurs in every bone of the foot. About one-third are located in the hindfoot, and 20% of the total occur in the calcaneous. Ewing's of the foot is a highly aggressive tumor with frequent metastasis. A complete cancer staging work-up is required and a carefully planned biopsy should be the last step in the sequence. Incidence and Demographics: Ewing's sarcoma is most common in the first and second decade. The ratio of male to female is 3:2. The mean age at diagnosis of patients with tumors in the foot is 17 years. Symptoms and Presentation: Patients normally have pain accompanied by significant diffuse swelling. The area may appear inflamed and a misdiagnosis of infection can be made. The white blood cell count, erythrocyte sedimentation rate and temperature may all be moderately elevated. Patients have symptoms for an average of 14 months prior to diagnosis. Patients with hindfoot lesions have an average duration of symptoms of 22 months prior to diagnosis, whereas those with forefoot lesions have an average duration of symptoms of seven months. X-Ray Appearance and Advanced Imaging Findings: Radiologically, Ewing's sarcoma is often associated with a lamellated or "onion skin" periosteal reaction. This appearance is caused by and splitting and thickening of the cortex by tumor cells. The lesion is usually lytic and central. Endosteal scalloping is often present. The "onion-skin" appearance is often followed with a "moth-eaten" or mottled appearance and extension into soft tissue. Bone marrow infiltration is not obvious on plain x-ray. The radiologic appearance of Ewing's sarcoma in the foot is highly variable. The tumor may present as a small lytic lesion with a permeative appearance and no matrix or soft tissue calcification. In other cases the lesion causes permeative lysis accompanied by marked sclerosis. In an unusual case involving the distal fibula, the lesion appeared entirely cystic and was mistaken for a unicameral (simple) bone cyst. Bone scan shows abnormal uptake, which may be intense. CT scan demonstrates the permeative destruction well. MRI is essential for surgical planning and demonstrates the soft tissue extent of the mass, which may be characteristically extensive; on TI-weighted images the tumor has low intensity compared to the normal high intensity of bone marrow. On 1:2 -weighted images the tumor is hyper intense compared to muscle. Ewing's sarcoma has increased uptake on bone scan. Differential Diagnosis: Infection, neuroblastoma metastasis, lymphoma, leukemia. Preferred Biopsy Technique: Open biopsy for bone lesions, core or tru-cut is often adequate for soft tissue lesions Preferred Margin for this Tumor: Wide Histopathology findings: Grossly, the tumor is gray to white in color and poorly demarcated. The consistency is soft and gray and sometimes semi-liquid especially after breaking through the cortex. Areas of hemorrhage and necrosis are common. The destruction is often greater on gross appearance than was visible on radiographs.Under the microscope, Ewing's sarcoma consists of densely packed uniform small cells in sheets. The cells have scant cytoplasm without distinct borders. The cells are two to three times as big as lymphocytes and have a single oval or round nucleus without prominent nucleoli. The tumor spreads through Haversian canals which cause the appearance of permeative margins on x-ray. Glycogen is present within the cells causing a positive reaction to periodic acid-schiff (PAS) stain. Most Ewing's sarcomas are positive with HBA-71 or 0-13 stain which is an antibody to the protein product of myc 2. The microscopic differential includes lymphoma and metastatic neuroblastoma which must be excluded by reticulin stain and urine vanillyl mandelic acid and homovanillic acid respectively. Rhabdomyosarcoma is ruled out if the specimen stains negatively with desmin, myoglobin and actin stains. A neural origin is supported by electron microscope findings of pseudorosettes. This is further supported by the common finding in Ewing's sarcoma and primitive neuroectodermal tumors of choline acetyltransferase and the translocation t(11:22)(q24;ql2). It is thought that Ewing's sarcoma with its few organelles is the poorly differentiated end of the spectrum of PNET. Neuroepithelioma is an example of well differentiated PNET and has neurosecretory granules and neuritic processes Treatment Options for this Tumor: Treatment consists of chemotherapy, radiation therapy, and surgical resection depending on stage and extent of disease. Ewing's sarcoma in the foot with regional metastasis can be treated with radiation of the primary, resection and radiation for the metastasis plus chemotherapy in order to balance the positive and negative effects of treatment in the setting of a relatively poor prognosis. Outcomes of Treatment and Prognosis: Survival is highly dependant on the stage of the disease and may also vary according to location. Patients without metastasis had 88% survival, whereas those with non-pulmonary and pulmonary metastasis had 10% and 0% survival, respectively. Patients with tumors in the forefoot had 70% survival and those with tumors in the hindfoot had 33% survival. Tumor size and delay before diagnosis also vary by site, and these factors are likely to have a greater impact on prognosis than the difference in site alone.
Ganglionic Cyst
Introduction and Definition: The origin of ganglion cysts is unclear but they are commonly associated with degenerative conditions of soft tissue or bone. They may occur adjacent to joints, tendons, fascial planes, and within bone. Symptoms and Presentation: Most ganglion cysts can be definitively diagnosed based on a careful history and physical examination. By history the lesion has a tendency to both increase and decrease in size over time. On exam, ganglion cyst typically has superficial location, and may be adjacent to a joint. When these lesions occur near a joint, there is often osteoarthritis seen on the xray. The mass is soft when the nearby joint is relaxed, and becomes firm when the nearby joint or muscle is tensed. A pen light or a small laser pointer will transilluminate the cyst. X-Ray Appearance and Advanced Imaging Findings: Most ganglion cysts can be definitively diagnosed based on a careful history and physical examination. By history the lesion has a tendency to both increase and decrease in size over time. On exam, ganglion cyst typically has superficial location, and may be adjacent to a joint. When these lesions occur near a joint, there is often osteoarthritis seen on the xray. The mass is soft when the nearby joint is relaxed, and becomes firm when the nearby joint or muscle is tensed. A pen light or a small laser pointer will transilluminate the cyst. Preferred Biopsy Technique: If the initial assessment yields the expected results, one attempt at aspiration with a large bore needle should be performed. Aspiration of the characteristic clear viscous material from the mass confirms the diagnosis. If the characteristic fluid is not obtained, no further attempts should be made Treatment Options for this Tumor: Once confirmed, the cyst may be treated with aspiration and injection with cortisone, which should lead to resolution in about half the cases. Surgical removal is indicated for persistent, large or troublesome cysts. The mass should explored and the origin of the cyst and the stalk identified, if possible. A portion of the joint capsule and the stalk should be excised in continuity with the mass. Loupe magnification and tourniquet hemostasis will assist in visualization of the stalk and may decrease the risk of recurrence. Outcomes of Treatment and Prognosis: Approximately 10% of these cysts recur following surgery.
Giant Cell Tumor of Tendon Sheath
Introduction and Definition: Giant cell tumor of tendon sheath is a rare, solitary benign soft tissue tumor which may arise in the tendon sheath tissues around the ankle and the toes of the foot. Most cases occur in the hand, where local recurrence after excision has been reported in up to 40% of cases. Approximately 3 - 10% of these tumors occur in the foot, most commonly in the forefoot, especially the great toe. Incidence and Demographics: Most patients are young adults, around age 30. Symptoms and Presentation: Clinically, the patients report a slow growing painless, firm solitary mass adjacent to the dorsal or plantar tendons, the midfoot joints, or the ankle joint, which has been present for one to two years on average. There may be a history of trauma, and neurological symptoms occur rarely. In one study, lesions in the forefoot occurred in the first, second, and fifth rays exclusively, indicating that there may be some relationship between weight-bearing and this tumor. The tumor may cause or accentuate an angular deformity such as hallux valgus. X-Ray Appearance and Advanced Imaging Findings: On plain radiographs, there may be a visible soft tissue swelling, sometimes completely encasing the bony elements of the involved digit, and the tumor may invade the adjacent bone and cause cystic lesions that are clearly visible on xray. Approximately 10% involve bone. The bone involvement and destruction leads to concern for primary bone malignancy, and inappropriately aggressive treatments can result. CT scan will show the extent of the tumor, and clearly delineate any bony involvement. Some of these tumors have small calcifications, feature shared with synovial sarcoma. MRI scans are helpful to define the extent of the lesion, and can be helpful in the preoperative diagnosis. Hemosiderin in the lesion may result in vary low signal intensities on some sequences, and the lesions enhance on T1 sequences after administration of gadopentetate contrast agent, and these features help identify the tumor Differential Diagnosis: Based on the location, age, and invasiveness of the tumor, the differential diagnosis may include a large number of benign and malignant lesions, including synovial sarcoma, chondromyxoid fibroma, enchondroma and chondrosarcoma, giant cell tumor, and pigmented villonodular synovitis. Due to be overlapped between the clinical and radiological features of this tumor and that of certain sarcomas, healthcare providers that are not tumor specialist should take great care in managing patient's home they suspect have giant cell tumor of tendon sheath Preferred Biopsy Technique: An open, separate, staged biopsy is strongly recommended Preferred Margin for this Tumor: Marginal Histopathology findings: A separate, staged biopsy is strongly recommended. The lesion cannot always be characterized by the preoperative studies, and aggressive or destructive features may be present that are also consistent with malignancy. Open surgical biopsy with frozen section analysis is preferred, performed through a well planned longitudinal incision that avoids any involvement of nearby neurovascular structures. If the lesion can be characterized by MRI, and the level of confidence in the preoperative diagnosis is very high, then excisional biopsy is appropriate. Grossly, the lesion is a nodular, multilobulated soft tissue mass 1-3 cm in size, although neglected cases may be larger. Histologically, the lesion is similar to pigmented villonodular synovitis. There is hemosiderin and frequent macrophages, foam cells, and scattered giant multi-nucleated cells. The origin of the tumor is unclear. DNA aneuploidy, chromosomal translocations, and tumor expression of p63 and nm23 have been reported in a variable proportion of cases. Expression of p63, has been identified in giant cell tumor of bone, pigmented villonodular synovitis, and the giant cell tumor of tendon sheath, leading to speculation that these may share a common origin. The giant cells in all 3 of these tumors have been found to demonstrate features that are associated with osteoclast, including tartrate- resistant acid phosphatase marking, and calcitonin receptor expression Treatment Options for this Tumor: Treatment is by complete, meticulous excision of the entire lesion. A wide a radical margin is not necessary. Intralesional margins are acceptable, as long as complete excision is not compromised. Recurrence has been reported in up to 45% of cases, but with careful removal, recurrence can be reduced to 10 to 20%. In the lesser toes, where the lesion has extensively invaded the soft tissues and bone, amputation may be preferable to excision. In the great toe, efforts should be made to preserve the mechanical integrity of the first ray, including complete meticulous excision of the lesion, followed by bone grafts, skin grafts, and fusions as necessary. Outcomes of Treatment and Prognosis: In the office experience, initial treatment of these lesions is often by partial resection and recurrence is common. When the lesion extensively involves the local anatomy, the resection may lead to compromise of neurovascular status. However, it may be preferable to save a partially insensate digit rather than resort to amputation. In most cases, meticulous marginal resection leads to preservation of the digit with good function.
Giant Cell Tumor
Introduction and Definition: Giant cell tumor is a benign but locally aggressive tumor that can occur in any bone. Giant cell tumor accounts for 5 to 9 percent of all primary bony tumors. Giant cell tumors are usually found in the long bones, most often the distal femur, proximal tibia, and distal radius. Whether that tumor arises in the epiphysis or distal metaphysis is a matter of controversy, but giant cell tumors only occur after the epiphyseal plates have closed and a diagnosis of GCT in a patient with open growth plates should be questioned. This tumor is uncommon in the foot. The lesions are located in the metaphysis adjacent to the epiphysis or epiphyseal scar. For this reason, the lesions are located proximally in the first metatarsal and distally in the lesser metatarsals due to the location of the epiphysis. The tumor can cross joints and affect several adjacent bones. In time, the cortex may be expanded and even destroyed. In smaller bones, the lesion can slowly expand the entire bone into an oversized balloon with cartilage on the end. It is believed by some to be potentially malignant. In the very rare instances this lesion has the potential for metastasis to the lungs and in these cases the lung lesions may behave in an indolent fashioned and even require no treatment. The authors recommend a chest CT scan for all patients newly diagnosed with GCT.
Incidence and Demographics: It possibly is the most common bone tumor in the young adults aged 25 to 40. Giant cell tumor is found more commonly in women than men, and occusr most often during the third decade. Symptoms and Presentation: Most patients present with slowly progressive pain, with or without a mass. Symptoms arise when the lesion begins to destroy the cortex and irritate the periosteum or when the weakening of the bone caused by the tumor causes pain due to imminent pathologic fracture. Some giant cell tumors present with a pathologic fracture. X-Ray Appearance and Advanced Imaging Findings: Plain radiographs show a lytic lesion without matrix mineralization most often eccentrically placed to the long axis of the bone. The epicenter is in the metaphysic and is most radiolucent with increasing density towards the periphery. There is a well-defined in defect in the metaphysis and epiphysis, with destruction of the medullary cavity and adjacent cortex. The tumor expands into the epiphysis until it reaches the subchondral bone, which seems to be a partial barrier to further growth. Intact borders and a sharp inner margin may be associated with a better prognosis. These tumors often thin the cortex, and may expand into the soft tissues surrounding the bone, or they may expand the bone extensively, remaining within an eggshell-thin rim of periosteal new bone. Differential Diagnosis: Preferred Biopsy Technique: Preferred Margin for this Tumor: Histopathology findings: The gross appearance of the giant cell tumor is pain and, firm, and homogeneous, with foci of hemorrhage or necrosis. Microscopically, there are numerous multinucleated giant cells. The stromal cells are homogeneous mononuclear cells with around or ovoid shapes, large nuclei and indistinct nucleoli. The nuclei of the stromal cells are identical to the nuclei in the giant cells, a feature that distinguishes giant cell tumors from other lesions that also contained giant cells. Another feature of giant cell tumor is that the giant cells may contain very large numbers of nuclei, often several hundred. In some tumors, the giant cells can be seen to be engulfing more nuclei from the stroma Treatment Options for this Tumor: Treatment of giant cell tumors is by surgery only. Intralesional excision by "extended" curettage is the treatment of choice. Curettage alone is associated with a high recurrence rate, and this can be decreased with the addition of chemical cautery using phenol, multiple freeze-thaw cycles using liquid nitrogen, and treating the walls of the cavity with a high-speed rotary burr. Local recurrence after curettage alone is thought to lead to recurrence in 50% of cases. Recurrence after extended curettage is approximately 10 percent. The tumor cavity may be filled with polymethyl methacrylate cement or bone graft, according to the surgeon's preference. Some believe that the polymethyl methacrylate cement lowers the risk of a local recurrence due to the large amount of heat given off during hardening. Recurrences are normally treated with a second interlesional surgery. Bone graft may allow for more favorable biomechanics of load inthe nearby joint. The early signs of local recurrence may be more difficult to detect in cases treated with bone graft. Lesions that are highly expansile and destructive, or lesions that occur in "expendable" bones such as the proximal fibula (shown here) may be excised with a wide margin. Multiply recurrent giant cell tumors are also treated with wide resection. Giant cell tumor may occur in the sacrum, a site where complete surgical excision is very difficult. Intralesional removal of as much of the lesion as possible followed by radiation to the tumor site has been associated with acceptable tumor control. There is concern about secondary malignancy arising in irradiated giant cell tumors. A variety of reconstructive methods are utilized depending on the extent of bony defect, or no reconstruction may be necessary. Chemotherapy is not used. Outcomes of Treatment and Prognosis: Following surgery, patients should be made aware of the ongoing risk of local recurrence. Patients should be followed on a regular basis for the first 2 years at least. Local recurrence of giant cell tumor should trigger a complete workup including CT scan of the chest, abdomen and pelvis.
Glomus Tumor
Introduction and Definition: Glomus tumor is a rare and benign vascular tumor. The normal glomus unit is a neuromyoarterial apparatus that functions to regulate skin circulation and is found subungually, on the finger tip pulp, on the base of the foot and the rest of body in descending order. The most common site of glomus tumors is subungual and 75% of the lesions occur in the hand. Other sites include the palm, wrist, forearm and foot. Glomus tumor can occur near the tip of the spine, where it may arise from the glomus coccygeum. Glomus tumors have also been described in locations where the glomus body does not normally occur. Unusual sites include the patella, bone, chest wall, eyelid, colon, rectum, cervix, and other sites. Glomus tumors rarely arise directly from bone. Incidence and Demographics: The lesions present most frequently during the fourth and fifth decade of life although they can be found in any age and at any site. The subungual tumors affect women three times more commonly than men. Symptoms and Presentation: Clinically, glomus tumors are characterized by a triad of sensitivity to cold, localized tenderness and severe intermittent pain. The pain can be excruciating and is described as a burning or bursting.The exact cause of the pain is not completely understood, but nerve fibers containing the pain neurotransmitter substance P have been identified in the tumor. X-Ray Appearance and Advanced Imaging Findings: Radiologically, glomus tumors appear as well circumscribed osteolytic lesions. The lesion shows either bone erosion or invasion depending on where it arises. A sclerotic border is present due to the slowly enlarging mass. CT scan shows a non-specific subungual mass. T1 MRI is not as useful for subungual lesions as it only demonstrates a dark, well delineated mass. Glomus tumors appear as a very high and homogeneous signal intensity on T2 weighted images. MRI is useful for the detection of lesions in the soft tissues. The radiological differential includes epidermal inclusion cyst, enchondroma, chronic osteomyelitis, sarcoidosis, metastatic carcinoma, subungual melanoma and osteoid osteoma Differential Diagnosis: Preferred Biopsy Technique: Preferred Margin for this Tumor: Histopathology findings: Grossly, the tumors are usually less than one cm. in size, and appear as small red-blue nodulas. The lesion appears as a localized dark red or blue lesion beneath the finger nail, but the subungual lesions can be difficult to detect on clinical examination. Radiographs of the distal phalanx show a small scalloped osteolytic defect with a sclerotic border. Under the microscope, glomus tumors are found at the dermal and subdermal junction and have a fibrous capsule. They are made of an afferent arteriole, anastomotic vessel, and collecting venule. These vascular structures are surrounded by rounded uniform epithelioid cells with granular cytoplasm known as glomus cells or pericytes. Also present are smooth muscle cells and non-myelinated nerve cells. There is no pleomorphism or mitotic activity. There are three forms of glomus tumors: vascular, myxoid and solid. The vascular form consists of mostly vessels with little epithelioid component. The solid form has sheets of glomus cells with few vessels. Glomus tumors stain positive for the smooth muscle marker actin Treatment Options for this Tumor: Treatment of glomus tumors consists of surgical excision. Repair of the nail bed must be performed after the removal of subungual lesions. Outcomes of Treatment and Prognosis: Relief of pain is usually intermediate after surgery.
Osteoblastoma
Introduction and Definition: Osteoblastoma is a solitary, osteoid producing benign bone lesion which can demonstrate aggressive clinical behavior. Osteoblastoma and osteoid osteoma are histologically very similar, yet these two tumors are very different in their presentation, localization, radiographic appearance, treatment, and potential for recurrence. The foot is the 3rd most common location of osteoblastoma after the spine and the femur. 12.5% of osteoblastoma occur in the bones of the foot. Most occur in the hind foot, and the talus is most commonly affected bone. In one review of 41 osteoblastomas in the foot, two evolved into malignant sarcomas. Incidence and Demographics: Osteoblastoma predominantly affects young adults. The peak age of occurrence is approximately age twenty, though the tumor may present as early as age ten to as late as age sixty. Symptoms and Presentation: Common symptoms are pain of long duration, swelling and tenderness. Tumors of the spine can cause scoliosis and neurological symptoms. The lesion may clinically present with myleopathic and/or radicular symptoms. X-Ray Appearance and Advanced Imaging Findings: On x-ray, osteoblastomas appear as a radio-lucent defect with a central density due to ossification. The lesion is well circumscribed and may have a surrounding sclerosis. The tumor demonstrates increased isotope uptake on bone scan. Differential Diagnosis: osteoid osteoma, osteosarcoma, giant cell tumor and aneurysmal bone cyst Preferred Biopsy Technique: A biopsy is usually performed to confirm the diagnosis. Preferred Margin for this Tumor: Margins should be a s wide as possible without functional sacrifice Histopathology findings: On gross examination, osteoblastomas are red to tan in color with hemorrhagic areas. The compact tissue is granular, friable and gritty. The classic microscopic finding of osteoblastoma is irregular spicules of mineralized bone and eosinophilic osteoid rimmed by osteoblasts. The vascular stroma is characterized by pleomorphic spindle cells. The tumor cells differentiate into osteoblasts which make varying amounts of osteoid and woven bone. Cartilage production is a very rare finding in an osteoblastoma and should raise the suspicion of osteosarcoma Treatment Options for this Tumor: Surgical resection by curettage, intralesional excision or en-bloc excision are all treatment options depending on the site. Cryosurgery, radiation and chemotherapy may have a role in aggressive and surgically unresectable lesions of the spine. Outcomes of Treatment and Prognosis: Osteoblastoma vs. Osteoid Osteoma inconsistent pain vs.persistent, nocturnal pain irregular tissue pattern vs. regular pattern >2 cm vs. < 1 cm Sporadic reports of malignant sarcomas arising in osteoblastoma have been published. In addition, multiple authors have described a subset of these tumors that behaves in a much more locally aggressive fashion. These tumors have been found to be larger and occur in slightly older individuals. Microscopically, these tumors may have a distinct appearance, including epithelioid features and larger osteoblasts with abundant eosinophilic cytoplasm and vesicular nuclei. These tumors have been variously termed "aggressive osteoblastoma" or "malignant osteoblastoma". The radiographic and pathologic features of these tumors overlap with osteosarcoma.
Osteochondroma
Introduction and Definition: Osteochondroma, or osteocartilaginous exostosis, is the most common skeletal neoplasm. The cartilage capped subperiosteal bone projection accounts for 20-50% of benign bone tumors and 10-15% of all bone tumors.Osteochondromas are most likely caused by either a congenital defect or trauma of the perichondrium which results in the herniation of a fragment of the epiphyseal growth plate through the periosteal bone cuff. Osteochondromas can either be flattened (sessile) or stalk-like (exostosis) and appear in a juxta-epiphyseal location. Osteochondromas are also the result of radiation therapy in children. After the close of the growth plate in late adolescence there is normally no further growth of the osteochondroma. Incidence and Demographics: The lesions occur only in bones that develop from cartilage (endochondral ossification). Osteochondromas are found most often in long bones, especially the distal femur and proximal tibia, with 40% of the tumors occurring around the knee. Osteochondromas occur most frequently in the first two decades of life with a ratio of male to female of 1.5 to 1. Symptoms and Presentation: Clinically, osteochondromas present with pain due to mechanical irritation or a painless mass. A fracture can occur through the stalk of the lesion which also causes pain. X-Ray Appearance and Advanced Imaging Findings: Plain films are normally enough to diagnose osteochondromas. Sessile lesions cover a wide area and as a result cause metaphyseal widening or a "trumpet shaped deformity" on x-ray. Lesions with stalks are often found more distally and are common over the posterior femoral metaphysis. CT is helpful in determining if the marrow and cortices of the lesion are continuous with the bone. The relationship of the lesion to other structures and the thickness of the cartilage cap are best delineated with MRI. Differential Diagnosis: Preferred Biopsy Technique: Preferred Margin for this Tumor: Histopathology findings: On gross examination, an osteochondroma is an irregular bony mass with a bluish gray cap of cartilage. Opaque yellow cartilage has calcification within the matrix. The base of the lesion has a rim of cortical bone and central cancellous bone. Occasionally, a bursae develops over an osteochondroma. Normally, the cartilage cap ranges from 1-6 mm thick. Over 2 cm of cartilage or renewed growth of a dormant lesion are signs of possible malignant transformation.Under the microscope, an osteochondroma has endochondral ossification on the basal surface of hyaline cartilage so it resembles a normal growth plate with rows of chondrocytes. The cartilage is more disorganized than normal, has binucleate chondrocytes in lacunae, and is covered with a thin layer of periosteum Treatment Options for this Tumor: There is no treatment necessary for asymptomatic osteochondromas. If the lesion is causing pain or neurologic symptoms due to compression it should be excised at the base. Outcomes of Treatment and Prognosis: As long as the entire cartilage cap is removed there should be no recurrence. Patients with many especially large osteochondromas should have regular screening exams and radiographs to detect malignant transformation early. Special and Unusual Features: Hereditary multiple osteochondromatosis is an autosomal dominant condition that can lead to both sessile and pedunculated lesions. The lesions may occur on different bones or on the same bone, and symptoms present in the first decade of life. The risk of malignant transformation to chondrosarcoma in hereditary multiple osteochondromatosis is unknown, but may be 2530% compared to approximately 1% for a solitary osteochondromas.3 The risk of malignant degeneration increases as the number and size of the osteochondromas increases. In general, a sessile lesion is more likely to degenerate into sarcoma than an exostosis
Osteoid Osteoma
Introduction and Definition: Osteoid Osteoma is a benign bone lesion with a nidus of less than 2 cm surrounded by a zone of reactive bone. This lesion accounts for approximately 10 % of benign bone tumors. Approximately 11% of these painful, benign tumors occur in the bones of the foot. The neck of the talus is the most common location. Incidence and Demographics: The tumor occurs most frequently in the second decade, with a peak age in the early twenties,and affects males twice as often as females. Osteoid Osteoma is found in the diaphysis or the metaphysis of the proximal end of the bone more often than the distal end. Symptoms and Presentation: Osteoid osteoma has a distinct clinical picture of dull pain that is worse at night and disappears within 20 to 30 minutes of treatment with non-steroidal anti-inflammatory medication. Joint pain may be present with a periarticular lesion and synovitis can occur secondary to an intraarticular lesion. Local symptoms can include an increase in skin temperature, increased sweating and tenderness. Epiphyseal lesions can cause abnormal growth. X-Ray Appearance and Advanced Imaging Findings: The classic radiological presentation of an osteoid osteoma is a radiolucent nidus surrounded by a dramatic reactive sclerosis in the cortex of the bone. The center can range from partially mineralized to osteolytic to entirely calcified. The sclerotic bone surrounding the nidus can be minimal when the tumor involves a small bone. The lesion can occur only in the cortex, in both the cortex and medulla, or only the medulla. The reactive sclerosis may be present or absent. Bone scan shows a small, very intense focus of abnormal uptake. CT is the preferred method of evaluation, especially if the lesion is in the spine or obscured by reactive sclerosis. The four diagnostic features include: (1) sharp round or oval lesion (2) less than 2 cm in diameter (if the nidus is larger than 2 cm, the diagnosis of osteoid osteoma is excluded) (3) has a homogeneous dense center (4) has a 1-2 mm peripheral radiolucent zone Differential Diagnosis: osteoblastoma, osteomyelitis, arthritis, stress fracture and enostosis Preferred Biopsy Technique: Preferred Margin for this Tumor: Histopathology findings: On gross examination, osteoid osteoma is a brownish-red, mottled and gritty lesion that is distinct from the surrounding bone. It can be present in the cortex or medullary canal. Osteoclasts are present. The nidus is surrounded by sclerotic bone with thickened trabeculae. Microscopically, the nidus consists of a combination of osteoid and woven bone surrounded by osteoblasts. The oval shaped nidus is welvascularized and clearly separate from the reactive woven or lamellar bone. Treatment Options for this Tumor: In most cases, nonsteroidal anti-inflammatory medicines give substantial relief, and any history of taking these medicines should be carefully reviewed. If there is absolutely no relief of pain from taking NSAIDs, the diagnosis of osteoid osteoma is less likely. Lesions adjacent to a joint may cause ankylosis or mimic a pauciarticular inflammatory arthritis, such as Reiter's disease. The local swelling, erythema and tenderness can mimic infection. When there is significant involvement of a nearby joint, the relief from nonsteroidal medicines can be less dramatic. Patients who respond well to NSAIDs and aspirin may be successfully treated with these medications until the lesion disappears. The average time to resolution is 22 months. Many patients will not be able to tolerate the pain this long, and request surgical removal. For these cases, the goal is complete removal of the lesion by the least invasive means possible. For lesions in the hindfoot and midfoot, radio thermal ablation by CT guided needle is the recommended technique. A radiofrequency generator forms an alternating high frequency radio wave that passes from the electrode tip into the surrounding tissue, where energy is dissipated as heat. The tissue itself is heated, not the radiofrequency probe. The high success rate combined with the extremely low rate of complications strongly favor this technique. Radio thermal ablation can be difficult in the smaller bones because of difficulties with targeting the lesion in the CT scanner. In addition, when the lesion is in a small bone, there is risk of damage to nearby tendons or neurovascular structures. For superficial lesions in the forefoot, open surgery is still the preferred treatment. The surgeon needs to be able to locate the nidus using radiographs, anatomic landmarks, and direct observation. Other techniques for locating the nidus have been described. The surrounding reactive bone can be extremely dense, and it may also be hypervascular and somewhat porous. Outcomes of Treatment and Prognosis: It is essential to remove the entire nidus because failure to do so will lead to recurrence. Surgical removal often leads to weakening of the affected bone, and bone grafting, plating, and prolonged nonweightbearing with activity restrictions may be necessary.
Unicameral Bone Cyst
Introduction and Definition: Unicameral bone cyst (UBC), also known as simple bone cyst, is a benign lesion of uncertain origin that consists of a fluid filled cavity lined by a thin membrane. Several etiologies have been proposed, including expansion of synovial tissue trapped in the bone during development, local failure of ossification, or obstruction of the venous outflow of the bone. They are found in the metaphysis of long bones, with the most common site being the proximal humerus, followed by the proximal femur. In the foot, UBC occurs almost exclusively in the calcaneus. The location and appearance is characteristic and biopsy may not be needed to confirm the diagnosis. The location is very specific. The lesion is in the lateral portion of the calcaneus sub-adjacent to the middle facet. The apex of the lesion is towards the forefoot. The margin of the lesion is sharply defined, sometimes with a sclerotic rim. There is no matrix mineralization or periosteal reaction. Incidence and Demographics: UBC's are found most commonly in children between the ages of ages 5 to 20 years old, and the ratio of male to female is 2:1. Symptoms and Presentation: Most UBC's are asymptomatic and only present when a pathological fracture occurs or it may presents as an incidental finding or with mild aching pain during sports or running. X-Ray Appearance and Advanced Imaging Findings: The plain film is usually enough to make a diagnosis of a UBC. The lesion appears as a well defined osteolytic area with a thin sclerotic margin. It fills and perhaps slightly expands the juxta-epiphyseal metaphysis of the bone. The lesion is relatively symmetrical with respect to the midline axis of the bone. The lesion is not eccentric and does not break out through the cortex or form any extra osseous mass. There is no periosteal reaction visible unless there has been a previous fracture. A fragment of cortex that has fallen into a dependent position inside the cyst is known as the "fallen leaf" or "fallen fragment" sign. On MRI the lesion has high signal intensity with minimal loculations or heterogeneity consistent with a fluid filled cavity. Differentiation of UBC from other similar lesions should be possible based on the MRI findings. Intraosseous lipoma tyopically has signal intensity consistent with adipose tissue (high signal intensity on T1 and T2 alike) and aneurysmal bone cyst has a multiloculated appearance with fluid-fluid levels with each loculation. On CT the lesion has no matrix, and fills the bone to a variable degree. There is no periosteal reaction. The cortex is often quite thin. Bone scan is not recommended for these lesions Differential Diagnosis: Intraosseous lipoma, ABC’s Preferred Biopsy Technique: Preferred Margin for this Tumor: Intralesional Histopathology findings: Microscopically, the UBC has a membrane made up of a layer of flattened or cuboidal cells that resemble endothelium. The cyst fluid resembles synovial fluid. If a fracture has occured, there may be a hemorrhage, granulation tissue, calcifications, or giant cells which may confuse the diagnosis Treatment Options for this Tumor: Displaced fractures through UBC in the calcaneus are uncommon. Treatment for asymptomatic cases consists of observation and follow-up radiographs to insure the lesion is not growing or changing. Painful cysts can be treated with a wide variety of more or less invasive techniques and there is a lack of consensus as to the optimum choice of treatment. Minimally invasive techniques including aspiration and injection with methylprednisolone, bone marrow, autogenous or allogenous bone graft or bone graft substitutes, or a combination of these, or curettage without grafting, creating multiple drill holes, or percutaneous screw decompression. All of these techniques have been shown to be effective for some cysts. Virtually all the reports in the literature, however, have a relatively low level of evidence (level III, IV, V). New reports from a randomized, multi-center trial are due out soon, which apparently show no significant benefit for bone matrix or bone marrow preparations over simple injections of methylprednisolone. However, the biological mode of action of the injections remains unknown. Various technical factors have been proposed that may increase the success rate of steroid injections, including wide spacing of the needles to ensure complete exposure of the lesion, and using radiological dye to insure complete filling of the lesion. These techniques may decrease the need for multiple injections. The author of this site recommends that simple treatments with minimal morbidity be tried first, and that more invasive, expensive, and risky interventions be reserved for difficult cases. Outcomes of Treatment and Prognosis: These lesions usually heal when the patient is skeletally mature, but a few persist into adulthood. The lesions grow in proportion to the growth of the bone they are in. Once the bone is finished growing, the UBC should also stop growing. These lesions may recur, especially in younger children