Glycogen-rich clear cell carcinoma of the breast: a solid variant with mucus. A light microscopic, immunohistochemical and ultrastructural study of a case.

The light microscopic, immunohistochemical and ultrastructural features of a clear cell carcinoma of the breast have been studied. Both intraductal and invasive components were found. Histochemistry showed large amounts of intracytoplasmic glycogen and sparse neutral mucin in the tumour. The tumour cells were stained by antisera to carcinoembryonic antigen, keratin and epithelial membrane antigen, but not by antisera to alpha-lactalbumin, desmin or vimentin. Ultrastructurally, the epithelial derivation of the tumour was confirmed. Only a few intracytoplasmic lumina were demonstrated. The tumour was classified as a mucin-containing variant of glycogen-rich, clear cell carcinoma of the breast.