Tc-99m MIBI/Tc-99m MDP mismatch: A useful scintigraphic finding in differentiating myositis ossificans from malignant tumor of soft tissue

Myositis ossificans is a rare condition characterized by the abnormal formation of bone in the soft tissue. It has been classified in 2 forms whether it follows trauma or not. The condition is usually confused with infection or malignancy of soft tissue according to the clinical setting. Radiography is the preferred method of initial imaging, but it may not detect the lesion in the first 1 to 2 weeks. Bone scintigraphy is the method of choice for early detection of the disease and for assessing the maturity of the lesion. We present the case of a 12-year-old boy with myositis ossificans of the thigh muscles demonstrated on bone scintigraphy, which was differentiated from malignancy on Tc-MIBI scintigraphy and hence, ulterior invasive investigation was avoided.