A Case of Tumor-Induced Osteomalacia: Finding the Culprit Acetabular Tumor and Successful Resection with a Novel Hip Joint-Preserving Surgery.

Introduction Tumor-induced osteomalacia (TIO) is a rare paraneoplastic disorder caused by tumors that produce fibroblast growth factor 23 (FGF23) resulting in phosphate wasting and inadequate bone mineralization. Complete resection of the tumor can be curative. However, these tumors are typically difficult to find anatomically due to small size and location. Case Report We present the case of a patient who presented for evaluation of recurrent fractures and hypophosphatemia in the setting of elevated FGF23 suggestive of TIO. 68Gallium-DOTATATE revealed multiple somatostatin avid lesions in several ribs, left acetabulum, sacrum, right tibia, and feet, some of which appeared with fracture on computed tomography scan, initially concerning for metastatic disease. However, the lesion in acetabulum was considered the culprit tumor given its remarkably higher maximum standard uptake values. Complete surgical removal of the FGF23-secreting tumor led to cure of this disease. Conclusion This case report highlights the challenges with functional imaging differentiating fractures from the culprit lesion and reports on a novel surgical technique that allowed for surgical cure while preserving the hip joint.