Bone tumour that typically affects the epiphysis of a long bone? NOT RELATED-OHO
**Core Concept**
The question is testing knowledge of bone tumors, specifically their location and characteristics. The correct answer is a type of bone tumor that primarily affects the epiphysis of long bones, which is a region of high cell turnover and growth.
**Why the Correct Answer is Right**
The correct answer is a type of osteochondroma, which is the most common type of benign bone tumor. It typically arises from the metaphysis and extends into the epiphysis of long bones, leading to growth disturbances and potential complications. This type of tumor is characterized by a cartilaginous cap overlying a bony stalk, and it often causes pain and deformity if left untreated.
**Why Each Wrong Option is Incorrect**
**Option A:** Osteosarcoma is a malignant bone tumor that typically affects the metaphysis of long bones, not the epiphysis. It is the most common primary malignant bone tumor in children and young adults.
**Option B:** Ewing's sarcoma is a highly malignant bone tumor that can affect any bone, but it typically presents as a destructive lesion in the diaphysis or metaphysis of long bones.
**Option C:** Chondrosarcoma is a malignant bone tumor that arises from cartilage and typically affects the metaphysis of long bones. It is less common than osteosarcoma and often presents with pain and swelling.
**Clinical Pearl / High-Yield Fact**
The "Codman triangle" is a classic radiographic sign of osteosarcoma, which appears as a triangular area of new bone formation resulting from the periosteal reaction to the tumor.
**Correct Answer:** A. Osteochondroma