55 year old male with dedifferentiated chondrosarcoma and pathological fracture.
Final Diagnosis: Left proximal femur and soft tissues, en bloc excision:
Final Diagnosis Comment: Sections show a well-differentiated cartilaginous neoplasm based in the medulla, immediately adjacent to a cellular, high grade, poorly differentiated sarcomatous component. The latter dominates the soft tissue extension and grows mainly in an infiltrative, sheet-like pattern. However, some areas form filigree osteoid, raising a differential diagnosis of chondroblastic osteosarcoma. Dedifferentiated chondrosarcoma is nevertheless favoured due to the minimal cytologic atypia in the chondroid component, the abrupt transition, and the predominance of the poorly differentiated portion in the soft tissue extension; some degree of osteosarcomatous differentiation can often be found in association with dedifferentiated chondrosarcoma.
Case dedifferentiated chondrosarcoma and pathologi ... courtesy of Dr. Frank Gaillard, Radiopaedia.org