[Morphological changes of eosinophilic coarse granules in epithelial cytoplasm of breast adenosis].

<b>Objective:</b> To investigate the morphological changes and immunophenotypic characteristics of eosinophilic coarse granules in the cytoplasm of epithelial cells of breast adenosis, and their clinicopathological significance. <b>Methods:</b> A total of 64 cases containing eosinophilic coarse granules in the cytoplasm of breast epithelial cells admitted to the Department of Pathology of the Seventh Medical Center of People's Liberation Army General Hospital and the Department of Pathology of Shandong Provincial Maternal and Child Health Care Hospital Affiliated to Qingdao University for admission and consultation from December 2019 to August 2023 were collected. The distribution and morphological characteristics of eosinophilic coarse granules in the epithelial cytoplasm in 64 cases of breast adenosis were observed. Some cases underwent immunohistochemical staining of lysozyme, α-antitrypsin, α-antichymotrypsin, cathepsin D, EMA, panCK, ER, PR, AR, GCDFP-15, Syn, CgA, NSE, CD68, S-100, anti-mitochondrial antibody, p63, and SMA; and some cases were stained with mucicarmine, and AB-PAS histochemical staining before and after amylase digestion. <b>Results:</b> The eosinophilic coarse granules in the breast epithelial cytoplasm of 64 cases were seen accidentally, of which most (43 cases) were located in adenosis adjacent to the intraductal papilloma. By HE sections, eosinophilic coarse granules were found with diffuse distribution in the cytoplasm, which were round in varying sizes, pink-bright red, and with a certain degree of refractivity. The size of the coarse granules could be divided into three types: small, medium and large. The medium to large granules were more prominent in the lesions. The eosinophilic coarse granules were all positive for lysozyme, α-antitrypsin, α-antichymotrypsin, cathepsin D, EMA and S-100. ER and PR were all nonclonal positive in glandular epithelial cells. Histochemical stains for PAS were all positive before and after digestion of amylase. AR, GCDFP-15, Syn, CgA, NSE, CD68 and anti-mitochondrial antibodies were all negative; mucicarmine and AB staining were also negative. <b>Conclusions:</b> The morphological characteristics and immunophenotype of cytoplasmic eosinophilic coarse granules in the epithelial cells of breast adenosis are the same as those of zymogen granules, their existence may be a non-specific morphological change, representing a metaplasia of breast epithelial cells. Positive results for lysozyme, antichymotrypsin, etc. cannot be considered evidence of specific cell differentiation. For the diagnosis of acinar cell carcinoma, it should be combined with morphological characteristics, immunohistochemical characteristics, etc. to make a comprehensive analysis.