Management of Glycogen-Rich Clear Cell Carcinoma of the Breast: A Case Report.

This case report presents an asymptomatic 75-year-old female with a screening mammogram revealing a left-sided breast lesion, ultimately diagnosed as glycogen-rich clear cell carcinoma (GRCC) following a comprehensive evaluation and histopathological confirmation. Initial ultrasound-guided biopsy suggested a papillary neoplasm, which was discordant, and was followed by a magnetic resonance imaging (MRI)-guided biopsy showing fibrocystic changes throughout and a complex sclerosing lesion with flat epithelial atypia. We proceeded with a lumpectomy without a sentinel lymph node biopsy. Final pathology revealed findings consistent with GRCC. A multidisciplinary discussion recommended forgoing axillary surgery and proceeding with radiation, hormonal therapy, and chemotherapy. This case highlights the challenges of diagnosing rare cancers, such as GRCC, and the importance of excisional biopsy in the diagnostic process. We also emphasize the importance of multidisciplinary tumor board discussions regarding rare lesions, such as GRCC, to help guide disease management and follow-up.