A 48-year-old woman had a left breast mass identified during routine breast cancer screening. The mammogram showed pleomorphic-segmental microcalcifications in the mediolateral-oblique view of the left breast. Ultrasonography showed a hypoechoic mass approximately 3.7 cm in diameter with multiple calcifications. Contrast-enhanced magnetic resonance imaging of the breast showed non-mass like enhancement of approximately 4 cm in diameter in the C area of the left breast. She was diagnosed with glycogen-rich clear cell carcinoma (GRCC) by ultrasound-guided vacuum-assisted biopsy. Nipplesparing mastectomy was performed along with sentinel lymph node biopsy. The intraoperative consultation suggested sentinel lymph node metastasis and we therefore performed axillary lymph node dissection. Pathological examination reported microinvasive carcinomas, 0.4 cm in maximum diameter, and extensive intraductal components, 5 cm in size. The tumor cells were stained on PAS staining, but the stains were digested with diastase. The cells were negative for adipophilin. GRCC was first reported by Hull et al. This is a rare type of breast carcinoma. There is no standard therapy for this disease or any data on the prognosis of breast cancer patients with GRCC.