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Extraskeletal osteosarcomas: a clinicopathologic study of 25 cases
M Lidang Jensen1, B Schumacher, O Myhre Jensen
1Department of Pathology, Centre for Bone and Soft Tissue Tumors, Aarhus University Hospital, Denmark.
The American Journal of Surgical Pathology
|May 20, 1998
Summary
Extraskeletal osteosarcoma is a highly aggressive cancer in adults, often presenting in the thigh. Alkaline phosphatase staining is superior to immunohistochemistry for diagnosis, aiding in differentiating it from other sarcomas.
Area of Science:
- Oncology
- Pathology
- Cancer Research
Background:
- Extraskeletal osteosarcomas are rare, high-grade malignant tumors.
- Accurate diagnosis is crucial for appropriate patient management and prognosis.
- Previous diagnostic methods lacked definitive differentiation from other pleomorphic sarcomas.
Purpose of the Study:
- To evaluate the immunohistochemical profile of extraskeletal osteosarcomas.
- To assess the diagnostic value of alkaline phosphatase staining.
- To correlate histopathologic factors with clinical outcomes.
Main Methods:
- Retrospective analysis of 25 extraskeletal osteosarcoma cases (1970-1995).
- Immunohistochemical evaluation using 10 antibodies.
- Alkaline phosphatase staining for differential diagnosis.
- Analysis of histopathologic factors (tumor size, depth, subtype, grade, MIB-1, p53) and clinical course.
Main Results:
- Extraskeletal osteosarcoma is a high-grade malignancy affecting adults (median age 67), commonly in the thigh.
- High rates of local recurrence (36%) and distant metastases (60%, primarily lungs) were observed.
- Median survival was 24 months, with a 5-year survival rate <25%.
- Alkaline phosphatase staining effectively differentiated fibroblastic subtype from malignant fibrous histiocytoma.
- MIB-1 proliferation index correlated with prognosis; MIB-1 <24% indicated longer survival.
Conclusions:
- Extraskeletal osteosarcoma exhibits highly aggressive behavior with poor prognosis.
- Alkaline phosphatase staining is a superior diagnostic marker compared to immunohistochemistry for differentiating extraskeletal osteosarcoma from other pleomorphic sarcomas.
- MIB-1 proliferation index is a significant prognostic factor.