A 22-year-old presents with a well-defined eccentric lytic lesion in the distal femoral epiphysis with a ground-glass matrix, soap-bubble appearance, and no periosteal reaction on plain radiography. Biopsy shows spindle cells with bizarre giant cells in a vascular stroma but no osteoid matrix. The most likely diagnosis is:
- A Osteosarcoma, telangiectatic variant
- B Aneurysmal bone cyst (ABC)
- C Giant cell tumor of bone (GCT) ✓
- D Clear cell chondrosarcoma
Explanation
Giant cell tumor of bone (GCT) classically presents in young adults (20–40 years), epiphyseal/epimetaphyseal location in a skeletally mature patient, with an eccentric lytic soap-bubble lesion extending to the subchondral bone. Histologically, GCT shows evenly distributed multinucleated osteoclast-like giant cells within a background of mononuclear stromal spindle cells; there is no osteoid, chondroid, or cystic lining. Telangiectatic osteosarcoma also has giant cells but with high-grade pleomorphism and osteoid. ABC shows cystic spaces lined by fibroblasts. Clear cell chondrosarcoma is much rarer and shows chondroid matrix.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.