Oncogenic osteomalacia: imaging studies.

X-ray und NMR imaging studies of a 34-year-old patient with tumor-induced hypophosphatemic osteomalacia (OM) are presented. Besides typical features of OM, periosteal new bone formation was noticed initially. After 17 months of conservative treatment with supplements of inorganic phosphorus and 1,25-dihydroxyvitamin D, bone density had increased but Looser's zones were still present, while periosteal new bone formation was strikingly less evident. At this time a tumor in the first left metatarsal space became palpable, was surgically excised and proved to be a low-grade synovial sarcoma with hypervascular and partially calcified structures. Six months later an X-ray survey showed no more signs of metabolic osteopathy. Preoperatively, the pronounced vascularity of the tumor could be demonstrated by angiography and NMR scanning.