A 45-year-old man presents with a lobulated medullary lesion at the proximal humerus with ring-and-arc calcification on X-ray (stippled chondroid matrix). There is no cortical destruction. Biopsy shows hyaline cartilage lobules with mild nuclear atypia. This is most consistent with:
- A Low-grade (Grade 1) chondrosarcoma ✓
- B Osteochondroma with cartilage cap degeneration
- C Fibrous dysplasia with chondroid metaplasia
- D Enchondroma
Explanation
Distinguishing enchondroma from low-grade chondrosarcoma is one of the most challenging problems in orthopedic oncology. Features favoring low-grade (Grade 1) chondrosarcoma: age >40, location in proximal humerus/pelvis/femur (not phalanges), pain at rest, cortical expansion/remodeling, size >4-5 cm, and mild nuclear atypia with occasional binucleate cells on biopsy. Enchondromas in phalanges (hand) are common and rarely malignant. At age 45 with humerus location, mild nuclear atypia, and ring-arc calcification, low-grade chondrosarcoma is the more appropriate diagnosis. Treatment is wide resection for confirmed chondrosarcoma (chemotherapy-resistant).
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.