Glomangiopericytoma causing oncogenic osteomalacia - A case report with immunohistochemical analysis

A 47-year-old woman suffered from gait disturbance due to back pain and mus cle weakness. Laboratory data showed serum hypophosphatemia, elevated alkal ine phosphatase, and a normal level of ionized calcium. Radiological examin ations revealed multiple pathologic fractures in the ribs and pubic rami. S he had had no episode of familial or any other notable disorder, and so she was initially treated with medication for adult-onset osteomalacia. Howeve r, 19 years later (when she was 66 years old), she noticed a soft-tissue tu mor in her buttock. The tumor was excised. The histological features were t hose of glomangiopericytoma characterized by both glomus tumorlike and hema ngiopericytoma-like structures. After removal of the tumor, her symptoms di sappeared immediately. Laboratory data normalized 8 months later. To our kn owledge, this is the first report of oncogenic osteomalacia caused by gloma ngiopericytoma.