We report a case of male primary breast cancer found incidentally on whole body FDG-PET/CT scanning with mammographic and histologic correlation. The relative lack of glandular activity in the male breast potentially increases the sensitivity of FDG-PET/CT for detection of male breast cancer. As in this case, even mild uptake in a male breast lesion should be regarded with suspicion. Although the incidental detection of breast masses on whole body FDG-PET/CT requires great vigilance, the modality provides both anatomic and physiologic data to help characterize primary breast cancer.