Intraosseous lipoma in the femoral shaft mimicking a bone metastasis on bone scintigraphy.

Primary intraosseous lipoma is a rare benign neoplasm of mature fat cells arising within the bone marrow, most commonly within the metaphysis of long bones. Involvement of the epiphysis or diaphysis is uncommon. An intraosseous lipoma typically shows no abnormal uptake of a bone-seeking agent. Bone scintigraphy demonstrated a focal area of uptake in the right femoral shaft mimicking a bone metastasis in a 52-year-old man with basal cell carcinoma of the face. Plain radiography showed a well-defined radiolucent lesion with endosteal erosion in the intramedullary portion. MRI showed no fat tissue in the lesion. Histology confirmed intraosseous lipoma with dystrophic calcification and myxomatous degeneration.