NEET-PG 2017 — Orthopaedics

Question 11: A 20-year-old college girl presents with pain in the upper part of tibia especially after dance classes. The pain has increased to a level that she cannot practice for forthcoming college festival. X-ray of the lower leg shows:

• A. Osteosarcoma
• B. Osteoblastoma (Correct Answer)
• C. Chondrosarcoma
• D. Pigmented villonodular synovitis

Explanation: ***Osteoblastoma*** - On X-ray, osteoblastomas commonly appear as a **lytic lesion** with a **sclerotic rim**, often larger than 2 cm, which can be seen in the provided image. The pain in the **tibia** that worsens with activity and affects a young individual is also consistent with the presentation of osteoblastoma. - This benign bone tumor is known to cause significant localized pain and can be found in the **metaphysis or diaphysis** of long bones like the tibia. *Osteosarcoma* - Osteosarcoma is a **highly aggressive malignant bone tumor** that typically presents with a **"sunburst" or "Codman's triangle"** appearance and areas of amorphous calcification (osteoid matrix) on X-ray, which are not clearly evidenced here. - While it can occur in young adults and cause pain, the radiographic findings are more indicative of a benign lytic lesion. *Chondrosarcoma* - Chondrosarcoma is a **malignant cartilaginous tumor** often characterized by **"rings and arcs"** or **popcorn-like calcifications** within a lytic lesion on X-ray, typical of cartilage matrix. - While it can cause pain, its radiographic features are distinct from those observed. *Pigmented villonodular synovitis* - This is a **benign proliferative disorder of the synovium** affecting joints or bursae, not primarily the bone itself. - It would typically demonstrate **erosions** and **soft tissue masses** within a joint on imaging, not a lytic bone lesion as shown.