Tumour induced osteomalacia due to a sinonasal hemangiopericytoma: A case report.

Tumour induced osteomalacia (TIO) is a rare and often unrecognized cause of hypophosphatemia. We report on a case of TIO due to a hemangiopericytoma originating from the left nasal sinus. The patient was a 55-year-old male with a 3-year history of left hip pain and an undisplaced left hip fracture. Biochemical testing demonstrated low levels of serum phosphate and serum 1,25-dihydroxyvitamin D, and an elevated level of fibroblast growth factor 23. Octreotide scanning demonstrated uptake in the left nasal sinus area and a computed tomography scan revealed a left nasal sinus mass. The patient underwent surgical resection of the mass and histology was consistent with a sinonasal hemangiopericytoma. His serum phosphate levels normalized almost immediately after surgery and he had complete resolution of hip pain. Our case highlights the importance of considering TIO when assessing patients with low serum phosphate.