KRT5 and breast angiosarcoma: Sometimes, basal cells are not easy to be found in HE staining, especially in intraoperative frozen sections, which is easy to be confused with adenocarcinoma, and we need to use the immunohistochemical staining markers of basal cells (p40, p63, CK5/6) to identify.[7] Immunohistochemistry showed the continuous presence of basal cells in the gland lumen or around the papilla, which is also the key evidence for the diagnosis of BA/CMPT.