[Primary intermediate hemangioendothelioma of bone: a study of 5 cases].

OBJECTIVE: To study the radiologic and pathologic features of primary intermediate hemangioendothelioma of the bone. METHODS: Five cases of primary intermediate hemangioendothelioma of bone encountered in the past three years were enrolled into the study. The clinical, radiologic, pathologic and immunohistochemical features of the tumors were reviewed. RESULTS: The patients included 3 children with Kaposiform hemangioendothelioma and 2 elderly with retiform hemangioendothelioma. Four of the cases affected long bones and the remaining case affected the clavicle. One case showed multifocal involvement of the humerus. Radiologically, the tumors showed borderline to low-grade bony destruction, with various degrees of cortical defect. Intralesional or perilesional bone formation was demonstrated in 4 cases and radial spicules were seen in 1 case. The histopathologic features of primary intermediate hemangioendothelioma of bone were similar to those of soft tissue, except for the presence of reactive bone formation. Immunohistochemically, the tumor cells were positive for CD31 (5/5), CD34 (5/5), vimentin (5/5) and smooth muscle actin (3/5) but negative for cytokeratin and epithelial membrane antigen. CONCLUSIONS: Primary intermediate hemangioendothelioma of bone is a distinct entity and similar histologic classification applies as in its soft tissue counterparts. Comparison of the biologic behavior requires long-term follow-up studies.

[Chondroblastoma occurring in atypical sites].

OBJECTIVE: To study the clinical, pathologic and radiologic features of chondroblastoma occurring in sites other than epiphysis and apophysis of long bones, and to investigate possible reasons for misdiagnosis. METHODS: The clinical, pathologic and radiologic data of 18 chondroblastoma cases occurring in atypical sites were collected from 5 major hospitals in Shanghai during the past 12 years. S-100 immunostaining was performed to confirm the cartilaginous differentiation of the tumor cells. RESULTS: Chondroblastoma occurred in small bones of feet in 10 of the 18 cases (55.6%) studied, being commonest in the talus and calcaneus bones. Mean age of the patients was 27.8 years, with 55.6% over 25 years of age. Radiologic examination revealed expansive, multilocular and well-demarcated radiolucent lesions in most cases. There was local cortical destruction in 5 cases (28%) and soft tissue infiltration in 1 case. In 10 cases (55.6%), the tumor was associated with aneurismal bone cyst or simple bone cyst formation. None of the cases studied was accurately diagnosed clinically before the operation. In 2 cases, the pathology was also misdiagnosed, often being diagnosed as aneurismal bone cyst or giant cell tumor. CONCLUSIONS: Chondroblastoma occurring in atypical sites are often associated with atypical age, radiologic features and pathologic findings at presentation. Thorough understanding of the potential pitfalls is essential in order to avoid misdiagnosis.