Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by excessive fibroblast growth factor 23 (FGF23) secretion, leading to chronic hypophosphatemia and osteomalacia. We report a case of a woman in her 30s with multiple pathological fractures and chronic hypophosphatemia. Laboratory tests showed elevated serum FGF23 levels. In-111 pentetreotide Somatostatin Receptor Scintigraphy (SRS) revealed abnormal tracer uptake in the right upper arm, which MRI confirmed to be a subcutaneous mass. Surgical resection of the tumor led to normalization of phosphate levels and undetectable FGF23 levels. Histopathology confirmed a phosphaturic mesenchymal tumor (PMT). This case demonstrates the utility of SRS for tumor localization in TIO and emphasizes the importance of early diagnosis and complete resection.
