What happened, in summary

A 55-year-old woman developed a growing right breast mass over 4 months. Examination showed redness, warmth, tenderness, and a hard mass about 15 cm across the upper and lower outer breast quadrants. Mammography showed a high-density 10 cm mass with suspicious calcifications and skin thickening, and ultrasound showed a solid heterogeneous mass. Core needle biopsy found an uncommon breast tumor, glycogen-rich clear cell carcinoma, with malignant epithelial cells containing abundant clear cytoplasm. The cells were strongly PAS-positive, cytokeratin AE1/AE3-positive, cytokeratin 7-positive, E-cadherin-positive, and negative for PAS-diastase, HER2, estrogen receptor, and progesterone receptor. p63 staining showed absence of basal cells. The diagnosis was glycogen-rich clear cell carcinoma infiltrating ductal carcinoma, and the receptor profile was triple-negative. She received neoadjuvant epirubicin and docetaxel every 3 weeks for 3 cycles and had a partial clinical response, but also developed skin ulceration over the tumor. Modified radical mastectomy with axillary lymph-node dissection followed. The tumor measured 7 by 7 by 4 cm and showed extensive necrosis, fibrosis, inflammation, and calcifications. Pathologic response was Miller-Payne grade G2, meaning less than 30% reduction in infiltrating tumor cellularity. Twelve removed axillary nodes were tumor-free, and staging was T4N0M0, Stage IIIB. She then received 3 more cycles of epirubicin and docetaxel, followed by 50 Gy radiotherapy to the chest wall and axillary/supraclavicular regions. At 14 months after surgery, she was asymptomatic and disease-free. The pathology was notable for clear cytoplasm and glycogen-rich staining, features that distinguish this rare breast cancer subtype from more common invasive ductal carcinoma patterns. The absence of nodal disease was favorable despite the large T4 primary tumor.