Oncogenic Osteomalacia Due to Tumor in the Femoral Head Managed by Excision and Femoral Head Preservation

Case: A 35-year-old man presented with low backache and bilateral hip pain for 3 years. On evaluation, he had elevated alkaline phosphatase (391.3 U/L) and low phosphorus (2.01 mg/dL). Imaging showed bilateral femoral neck insufficiency fractures, and 68 Ga-DOTANOC-PET-CT scan revealed a tumor in the femoral head. En bloc tumor excision with femoral head preservation under CT navigation was performed. Histopathology confirmed a phosphaturic mesenchymal tumor. Phosphorus normalized at the first-week review, and symptoms improved without supplements. Conclusion: Tumor-induced osteomalacia should be kept as a differential diagnosis in patients with generalized weakness and hypophosphatemia, and wide-margin excision results in permanent cure.