Myositis ossificans in the right inferior thoracic wall as an unusual cause of lower thoracic-upper abdominal pain: report of a case.

We report a case of thoracic wall myositis ossificans (MO) located anterior to the ninth rib, causing right lower thoracic-upper abdominal pain. The diagnosis was based on the findings of ultrasonography (US) and computed tomography (CT). Numerous disorders can be included in the differential diagnosis of right lower thoracic-upper abdominal pain, so we must first establish if the pain is somatic or visceral in origin. Somatic pain in this region can be caused by traumatic muscle pain, overuse myalgia, costochondritis, or thoracic wall malignancies. Although rare, MO should also be considered in the differential diagnosis of pain and thoracic wall masses in this region. As the calcifications may not be seen on a plain chest X-ray in the early course of this condition, superficial tissue US or CT should be performed to establish the diagnosis.