Myositis ossificans: the mimicker.

A 14-year-old boy presented with upper backache and a painful swelling in the right paraspinal region for 7 days. He had no history of trauma. MRI showed a non-specific ill-defined heterogeneous lesion, which showed intense postcontrast enhancement. Ultrasonogram showed a peripheral sheet of calcification around the lesion. A CT scan showed a faint rim of calcification, which increased in thickness over weeks, confirming the diagnosis as myositis ossificans. We present our approach to the case and also review the imaging features of different stages of the disease process and their differentials.