Myositis ossificans of the thigh causing external compression of the superficial femoral artery and vein

Rationale: Myositis ossificans (MO) is a benign condition characterized by heterotopic bone formation in the skeletal muscle of extremities. Marked variation can occur in the incidence and location of the bone formed as well as resulting complications. Femoral vessel obstruction caused by MO is an extremely rare but disabling complication. Arterial occlusion may aggravate ischemic conditions, resulting in necrosis in the lower extremity. Patient concerns: We report a 41-year-old female with progressive pain and swelling of the right thigh region for 1 year. Diagnoses: We diagnosed it as obstruction of the superficial femoral artery and vein caused by external compression of the MO between the sartorius and vastus medialis of the thigh. Interventions and outcomes: Adherent tissues and mass were excised with care without damaging the femoral artery or the vein. However, normal morphology did not recover due to loss of elasticity of femoral vessels. Therefore, after resection of the narrowed region of the femoral artery, a femoral-to-femoral graft interposition using the greater saphenous vein was performed. At 12 months after the surgery, vessel reconstruction computed tomography images confirmed normal continuous flow of the femoral artery. Lessons: Vascular compression and peripheral inflammatory response due to MO can cause loss of normal vascular morphology. Surgical excision of the mass and the involved femoral artery segment followed by femoral arterial reconstruction should be considered for lesions that do not spontaneously regress to prevent functional impairment and secondary complications in extremities.