A 20-year-old woman has a 4 cm, well-defined, expansile lesion in the proximal tibia with 'soap bubble' appearance and cortical thinning on X-ray. On MRI the lesion extends to the articular surface. Biopsy reveals osteoclast-like giant cells on a mononuclear stromal background. Codman's triangle is absent. This is MOST likely:
- A Aneurysmal bone cyst
- B Chondroblastoma
- C Telangiectatic osteosarcoma
- D Giant cell tumor of bone (GCTB) ✓
Explanation
Giant cell tumor of bone (GCTB) is characterized by: (1) occurrence in skeletally mature individuals (fused physis), (2) epiphyseal/epimetaphyseal location extending to the subchondral bone, (3) soap-bubble radiolucency without matrix calcification, (4) cortical thinning/expansion without periosteal reaction or Codman's triangle, and (5) pathognomonic giant cell-rich histology on mononuclear stromal background. Aneurysmal bone cyst (ABC) also has soap-bubble appearance but shows fluid-fluid levels on MRI and is metaphyseal. Chondroblastoma is epiphyseal but occurs before physeal closure (younger patients) 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.