A 40-year-old woman discovered through palpation a tumor in the upper lateral quadrant of the left mammary gland. Mammography, ultrasonography (US), and magnetic resonance imaging (MRI) showed a 10 mm diameter tumor. Fluorine-18 fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) showed abnormal accumulation in the detected tumor, and the maximum standardized uptake value was 2.2. The patient underwent tumor resection. The postoperative histopathological finding was intraductal papilloma. The intraductal papilloma showed strong expression of glucose transporter (GLUT)-4 on membrane and/or cytoplasm, and weak expression of GLUT-1 and GLUT-3 by immunohistochemistry. This case suggests that other glucose transporters (e.g., GLUT-4), other pathological factors, and cytokines may have a close relation with (18)F-FDG accumulation in intraductal papilloma more than GLUT-1 or GLUT-3 expression.