Avascular necrosis of bone with rheumatoid vasculitis

A 76-year-old woman with classical rheumatoid arthritis presented with a left groin mass associated with radiologic erosion of the adjacent bony public ramus. The hip joint was not involved. Computerized tomography showed an encapsulated cyst of the pubic ramus that was surgically excised and measured about 6 x 8 cm. Histologic examination of the cystic mass and adjacent bone showed marked avascular necrosis, surrounded by an acute necrotizing vasculitis with fibrinoid necrosis. We postulate that, in this case, rheumatoid vasculitis caused an avascular necrosis of the pubic ramus.