Two Cases of Tumor-induced Osteomalacia Resulting in Surgical Resection During Burosumab Therapy.

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome that results from tumors that secrete fibroblast growth factor 23 (FGF23). This leads to chronic hypophosphatemia. Burosumab, an anti-FGF23 antibody, is an effective treatment when surgery is not possible; however, it complicates FGF23 measurements and postoperative monitoring.