Which tumor is most often located in the epiphysis of a bone?

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

Answer: (B)

Placing a lesion in the epiphysis points you toward tumors that originate near the joint surface, where cartilage is abundant. Chondroblastoma is the classic epiphyseal tumor, a benign neoplasm of cartilage-forming cells that almost always arises in the epiphysis of long bones in adolescents and young adults. This location—the end part of the bone adjacent to the joint—fits the typical presentation of chondroblastoma, often seen in the distal femur, proximal tibia, or proximal humerus near the joint.

In contrast, osteosarcoma tends to start in the metaphysis, right around the growth plate, and is aggressive with mixed lytic/blastic patterns and periosteal reactions. Ewing sarcoma usually involves the diaphysis and can show onion-skin periosteal layering with systemic symptoms. Chondrosarcoma generally affects older adults and often involves the pelvis or proximal femur, with a different age distribution and location pattern. So the epiphyseal location is the hallmark that makes chondroblastoma the best fit among these options.