Glomus Tumor: An Unusual Cause of Hypophosphatemic Osteomalacia

Background: Tumor-induced osteomalacia (TIO) is a rare condition resulting in hypophosphatemic osteomalacia. We present a rare case of TIO secondary to glomus tumor. Clinical Case: A 39-year-old woman with history of chronic sinusitis presented with progressively worsening generalized body pain and muscle weakness of eight months duration. Examination showed decreased muscle strength in bilateral upper and lower extremities and congenital cleft palate. Laboratory work up revealed elevated alkaline phosphatase 603 U/L (44–147 U/L), low serum phosphorus 1.5 mg/dL (3.5–5.0 mg/dL), normal serum calcium 8.9 mg/dL (8.3–10.4 mg/dL), normal 25-hydroxyvitamin D 32 ng/dL (30–100 ng/dL), elevated 1,25-dihydroxyvitamin D 62 g/mL (20–45 pg/mL), elevated intact PTH level 99.01 pg/mL (8–74 pg/mL), high normal 24 hour urinary phosphate levels 1100 mg/dl, and elevated FGF23 level 128 RU/mL (