Ga-68-DOTATATE PET/CT was performed in a 60-year-old man to detect culprit tumor responsible for tumor-induced osteomalacia (TIO). The images revealed multiple foci of abnormal activity in soft tissue lesion, which were not typical of tumor causing TIO in Ga-68-DOTATATE PET/CT. Considering other neoplastic processes, FDG PET/CT were subsequently performed, which showed all same lesions, although the lesions with highest activity were different between the scans. Pathological examination demonstrated that the patient experienced TIO caused by 1 lesion, but other lesions were due to IgG4-related lymphadenopathy.