Non-traumatic myositis ossificans circumscripta in the anterior abdominal wall of a seven-year-old Ugandan child: A case report.

Myositis ossificans circumscripta (MOC) is a benign and self-limiting heterotopic ossification in the subcutaneous fat, tendons, muscles, and nerves. It is commonly due to trauma and is frequently encountered in the arm, shoulder, thigh, and hand which are prone to trauma. Non-traumatic MOC arising from the abdominal muscles is extremely rare. We report a case of 7-year-old male child with a three-year history of progressive painless abdominal swelling in the left hypochondria region with no history of associated trauma. CT scan of the abdomen showed a well-defined hyperdense mass in the left external oblique muscle. Histological diagnosis confirmed myositis ossificans of the external oblique muscle. The mass was removed surgically with no immediate or late complications.