FGF23 and hypophosphatemia: Phosphaturic mesenchymal tumor (PMT) is a rare metabolic bone disorder characterized by abnormally elevated levels of fibroblast growth factor 23 (FGF23), which results in impaired renal phosphate reabsorption and reduced synthesis of 1,25-dihydroxyvitamin D. This leads to hypophosphatemia and osteomalacia, a condition also known as tumor-induced osteomalacia (TIO) (Boland et al., 2018; Chong et al., 2011).