[Pathoanatomical algorithm for differential diagnosis of Paget's disease of the breast].

Paget's disease of the breast is a rare type of cancer that affects the skin of the nipple and usually the areola. At the same time, most patients also have one or more tumors in the immediate vicinity of the focus of mammary Paget's disease. This tumor must be distinguished from normal or atypical Toker cells, and also differentiated from diseases such as Bowen's disease of the nipple and melanocytic lesions of the nipple and areola region, including nipple melanoma and BAP1-inactivated nevus (Wiesner nevus). Currently, there is no routine pathological diagnostic algorithm for these conditions. The aim of the work is to formulate a clear clinical and morphological algorithm for diagnosing Paget's disease of the breast and Toker cells, Bowen's disease of the nipple and areola, as well as melanoma and BAP1-inactivated nevi of the above localizations. Surgical material obtained from patients with Paget's disease of the breast (18), Toker cells of the nipple (2), Bowen's disease of the nipple (6), melanoma of the nipple (1), BAP1-inactivated nevus (1) was studied. The material was examined histologically with hematoxylin and eosin staining, Alcian blue and PAS reaction, as well as immunohistochemically with the following panel of antibodies: CD138, p53, CK8, CK7, HER2/neu, EMA, HMB-45, Melan A, S-100, p63, p16 and BAP1. An easy-to-learn pathoanatomical algorithm for diagnosing Paget's cancer has been developed, which will be especially useful for pathologists who encounter pathology of the nipple and areola in their work.