A case of oncogenic osteomalacia due to occult nasal sinus tumor

This paper shows a case of oncogenic osteomalacia in a 35-year-old man who presented with a 2-year history of generalized pain and progressive weakness of lower limbs, eventually became bed bound. At admission he had severe hip pain resulting from atraumatic femoral neck fractures. Laboratory investigations revealed hypophosphatemia, hyperphosphaturia, normocalcemia, elevated alkaline phosphatase, and normal serum levels of parathormone and 25-hydroxyvitamin D. Serum FGF-23 was elevated. Imaging showed osteoporosis and insufficiency fractures of the femoral neck. Whole body functional imaging failed to reveal any areas of increased activity. However, on computed tomography (CT) and magnetic resonance (MR) imaging, a tumor was discovered at left nasal cavity. The patient was treated with phosphate supplements and vitamin D, but his hypophosphatemia persisted. The tumor was surgically removed. Histologically, the tumor was diagnosed as variant of a sinonasal hemangiopericytoma-like tumor. After surgery, his symptoms were relieved and biochemical parameters normalized.