Histopathological and immunohistochemical findings in a case of glycogen-rich clear cell carcinoma of the breast.

Glycogen-rich clear cell carcinoma (GRCC) of the breast is a rare variant of primary breast carcinoma that was first described by Hull et al. in 1981, and is characterized by carcinoma cells containing an optically clear cytoplasm and intracytoplasmic glycogen. The present case involved a 33-year-old female. She had noticed a lump in the inner quadrant of the left breast. The tumor obtained by enucleation biopsy had an irregular shape. The tumor cells exhibited sharply defined borders, polygonal contours, a clear or finely granular cytoplasm, and moderate nuclear atypia. The tumor cells showed a positive reaction with periodic acid Schiff, eliminated by diastase digestion. The tumor was diagnosed as GRCC. There was no nodal metastasis. Immunohistochemically, the tumor cells were positive for cytokeratin, epithelial membrane antigen, HER2, and p53, but negative for estrogen receptor (ER) and progesterone receptor (PR). Although the biological behavior of GRCC is difficult to predict in view of the very limited number of case reports, the prognosis of GRCC may be associated with not only histopathological subtype but also other clinicopathological factors, such as size, status of invasion, status of nodal metastasis, nuclear grade, ER, PR, HER-2, p53 and so on. To clarify the pathogenesis of mammary GRCC, the systematic study of additional well-documented cases with long-term follow up will be necessary.