The patients, whose ages ranged from 32 to 81 years,⁷ presented with a mass accompanied by skin dimpling, nipple retraction, or pain in some cases. Both in situ and invasive lesions may be detected by mammography^{2,8,9,10,11,12} and sonography.^2,11 The imaging studies reveal an irregular spiculated mass^8,10,11,13 that may contain calcifications.^10,11,13

Glycogen-rich carcinomas resemble conventional breast carcinomas to the unaided eye. Distinctive macroscopic features have not been recorded. Most tumors measured between 2 and 5 cm; the largest spanned “about 15 cm.”¹³ In one series, the mean size was 3 cm.⁷ Observers have described the masses as “brownish pink-gray or whitish-gray.”⁷ The carcinoma can form multifocal or multicentric masses, and macroscopically evident involvement of the skin occurred in several cases.^7,14 The seminal authors could appreciate an in situ papillary component during macroscopic examination.²

Glycogen-rich clear cell carcinomas have basic structural features of ductal carcinoma in situ (DCIS) alone or of DCIS and infiltrating duct carcinoma. The intraductal component can grow in papillary, solid, cribriform, micropapillary, and “intracystic” patterns. Cytoplasmic clearing appears most evident in solid areas that also exhibit moderate nuclear atypia (Fig. 28.1). The cells in cribriform and micropapillary regions usually have low-grade atypia and less often appear water-clear. The neoplastic cells can undergo focal necrosis, but abundant, comedolike necrosis associated with high-grade nuclear atypia does not occur commonly.⁹ In most cases, one can detect small regions in which the cells contain eosinophilic and granular cytoplasm or exhibit other clear-cut apocrine features. The invasive component usually exhibits the histologic growth pattern of a conventional invasive duct carcinoma, but it can also display the patterns seen in lobular, medullary, and tubular carcinomas.³ The tumor cells typically form cords, solid nests, or papillary structures (Fig. 28.2). The formation of ductular or tubular structures occurs only rarely. The cells exhibit sharply defined borders and polygonal rather than rounded contours. The cytoplasm is clear or, less often, finely granular or foamy. Like the noninvasive component, the invasive carcinoma sometimes contains foci in which the cells have eosinophilic and granular cytoplasm that suggests an apocrine nature, and these cells often form a continuum with the clear cells. Observers have noted PAS-positive, diastase-resistant, intracytoplasmic hyalin droplets in rare cases.⁹ The nuclei appear hyperchromatic and
sometimes contain clumped chromatin and nucleoli. Mitotic figures are easily identified in most cases. One group¹⁵ found as many as 70 mitotic figures per 10 high-power fields. Patches of necrosis often occur in large tumors. A linear pattern consisting of strands of cells resembling invasive lobular carcinoma may be seen, and glycogen-rich variants of tubular, medullary, and endocrine carcinomas have been described.^3,7,16,17 The carcinoma cells can invade lymphatic vessels and nerves. The histologic appearance of the primary tumor is duplicated in the metastases, which also contain abundant glycogen.⁶