Chondroblastoma is most commonly found in which bone region?

• A. Diaphysis
• B. Metaphysis
• C. Periosteum
• D. Epiphysis

Answer: (D)

Chondroblastoma most often arises in the epiphysis of long bones, especially in adolescents. The epiphysis is the end part of a bone near the joint where growing cartilage resides, so lesions that develop from cartilaginous tissue typically appear there. Clinically this presents as joint-related pain with a radiographically well-defined, lytic lesion at the bone end, which may extend toward the metaphysis but remains centered in the epiphysis. The diaphysis (midshaft) and metaphysis are more characteristic of other conditions, and the periosteum is a surface covering rather than a bone region where this tumor originates. Thus, the epiphysis best fits the typical location of chondroblastoma.