Which bone tumor is most likely to be found in the epiphysis of a long bone?

• A. Osteosarcoma
• B. Ewing sarcoma
• C. Chondroblastoma
• D. Chondrosarcoma

Answer: (C)

Understanding where a bone tumor tends to arise helps identify what you’re likely dealing with. The epiphysis is the end portion of a long bone near the joint, and tumors that characteristically originate there are often cartilage-producing or enchondral in nature. Chondroblastoma is a classic example: it arises in the epiphysis of long bones, typically in teenagers and young adults, and can extend toward the adjacent metaphysis while remaining centered in the epiphyseal region. That epiphyseal predilection is what makes it the most likely tumor in this location.

In contrast, osteosarcoma usually starts in the metaphysis (the region near the growth plate) and often shows aggressive periosteal reactions. Ewing sarcoma tends to originate in the diaphysis (the shaft) and presents with systemic symptoms and characteristic imaging features like an onion-skin periosteal reaction. Chondrosarcoma generally occurs in adults and often involves the metaphysis or diaphysis of long bones, with a different clinical and radiographic profile.

So the epiphyseal localization strongly points to chondroblastoma as the best match.