The Histopathological and Immunohistochemical Features of Nipple Adenoma

Objectives: Nipple adenoma is a benign breast tumor presenting with nipple erosion and bloody nipple discharge, causing the clinical suspicion of Paget’s disease, and creating difficulty in diagnosis due to the histopathologically complex morphological pattern. In our study, we aimed to examine the histopathological and immunohistochemical features of this rare tumor. Materials and Methods: For this purpose, 11 nipple adenomas diagnosed in Ankara University Faculty of Medicine, Department of Pathology between 2005 and 2020 were included in the study. Clinical information was obtained from patient files. Histomorphological and immunohistochemically p63, SMA, kaldesmon, ER and CK5/6 staining properties of the tumors were evaluated. Accompanying ductal carcinoma in situ or invasive carcinoma rates were recorded. Results: The mean age of the patients was determined to be 44.1 years (minimum: 25, maximum: 59) and it was observed that all of the patients were female. Clinical presentation was with bloody or serous nipple discharge, subareolar nodule or a palpable mass. The average tumor diameter was measured as 0.9 cm (minimum: 0.4 cm, maximum: 1.2 cm). Sclerosing papillomatosis (36.4%), mixed (36.4%) and papillomatosis (27.2%) growth patterns were observed. Erosion was detected in the epidermis at a rate of 36.4%. Necrosis and cytological atypia were observed in areas of florid hyperplasia with a rate of 18.2%. Concomitant invasive ductal carcinoma (18.2%), low nuclear grade ductal carcinoma in situ (9.1%) and invasive lobular carcinoma (9.1%) were seen. Immunohistochemical analysis revealed the presence of p63, SMA, caldesmon positive myoepithelial cells in adenoma areas, heterogeneous positivity with ER and expression loss was not observed with CK5/6. Conclusion: Nipple adenomas are rare tumors that clinically and pathologically require the differential diagnosis of malignancy. In addition, close clinical follow-up of the patients should be performed, since breast carcinoma can be observed in the adenoma or in another location in the breast simultaneously or afterwards.