Immunohistochemical study in breast carcinoma. S100-protein positive cells and neuroendocrine differentiation

In this study S100-protein positive cells were found in all 12 cases of benign dysplastic changes and in all of the investigated 53 cases of breast carcinomas. These cells belong to interdigitating cells (IDC) and were located in a regular pattern in the basal cell layer of the ducts and alveolar nodules in benign lesions. However, in breast carcinomas S100-protein positive IDC were in various pattern of distribution; only in the stroma, in basal cell layer, between cancer cells and S100-protein positivity of IDC and epithelial cancer cells. This phenomenon suggests the antigenic modulation of cancer cells transferring them the property of S100-protein positive cells or it may be the consequence of fusion. Immunoreactivity for chromogranin A (ChgA) and synaptophysin (Syn) was found in epithelial cells in some cases of benign dysplastic changes. However, in some carcinoma cases ChgA and Syn were revealed in carcinoma cells, in myoepithelial cells, in some stromal mesenchymal cells and endothelial cells. Immunoreactivity to smooth muscle actin was shown in the endothelial and smooth muscle cells of the vessel's wall, in myoepithelial cells and was also sporadic in carcinoma cells.