Oncogenic Hypophosphatemic Osteomalacia Associated with a Nasal Hemangiopericytoma

We report a patient with a nasal hemangiopericytoma associated with an oncogenic hypophosphatemic osteomalacia (OHO). This syndrome results from tumor products that decrease renal tubular phosphate resorption, leading to the osteomalacia. This patient presented with classic bone manifestations of osteomalacia and a nasal tumor. Laboratory studies performed before the first resection of the tumor included normal serum calcium, hypophosphatemia due to decreased tubular reabsorption of phosphate, and an undetectable serum 1,25 dihydroxy vitamin D level. Serum parathormone level was normal. Anterior iliac crest bone biopsy showed characteristic signs of osteomalacia that included increased osteoid and delayed mineralization. A partial resection of the nasal tumor was performed. After the first surgery the patient showed detectable serum level of 1,25 dihydroxy vitamin D, and transient normalization of the tubular reabsorption of phosphate. The patient was also treated with phosphate supplements and vitamin D with transient control of her clinical manifestations and improvement of the radiographic signs of osteomalacia. Three months after surgery, the serum level of 1,25 dihydroxy vitamin D level again became undetectable. After selective embolization of the tumor, followed by an apparent complete tumor resection and postoperative radiation therapy, her hypophosphatemia and decreased phosphate tubular reabsorption persisted. Therefore, biochemical changes associated with hemangiopericytoma induced OHO may persist even after apparent total tumor resection. Clinicians should be aware of the oncogenic basis for some osteomalacia, as seen in this patient.