Culprit Tumor as an Unexpected Extraosseous MDP Activity on Bone Scintigraphy in a Patient With Tumor-Induced Osteomalacia

A 39-year-old man with bone pain underwent Tc-99m-MDP bone scan to assess skeletal lesions, which demonstrated multiple fractures and a focus of subtle extraosseous activity in the left thigh. A Tc-99m-hynic-octreotide imaging was performed due to the suspected diagnosis of tumor-induced osteomalacia, which revealed a hypermetabolic subcutaneous nodule in the left thigh, which exactly corresponded to the same site of MDP activity. Biopsy confirmed the subcutaneous nodule as the culprit tumor of tumor-induced osteomalacia. Bone scan, as a conventional imaging, provided useful information for detecting culprit tumor as shown in our case.