Tumor-induced rickets/osteomalacia (TIO): diagnostic pitfalls and therapeutic options.

This article focuses on tumor-induced rickets/osteomalacia (TIO), a rare acquired disorder characterized by excess fibroblast growth factor 23 (FGF23) causing hypophosphatemia and impaired bone mineralization. It presents a case of a 12-year-old girl with FGF23-related hypophosphatemic rickets/osteomalacia whose causative tumor was initially undetected by conventional imaging but later identified by detailed positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI). Surgical excision of the tumor, confirmed as a phosphaturic mesenchymal tumor producing FGF23, resolved her biochemical abnormalities and symptoms. The article discusses diagnostic challenges in differentiating TIO from genetic causes of hypophosphatemia, the utility of FGF23 measurement, and the importance of whole-body imaging for tumor localization. It also reviews current therapeutic options, emphasizing that complete tumor resection is the definitive treatment, while medical therapies such as burosumab can alleviate symptoms but do not cure the disease.