Carcinoma in situ in sclerosing adenosis of the breast: an immunocytochemical study.

In this report, seven cases of sclerosing adenosis of the breast are reported in which a lobular (5) or ductal (2) in situ carcinoma was also present. In two cases, mastectomy was performed because invasive carcinoma was diagnosed on frozen section. In the other cases, the referring pathologists initially considered the diagnosis of invasive carcinoma. A well-defined PAS-positive basal lamina (BL) was always present around the proliferating glandular structures. In addition, residual myoepithelial cells lying on the BL were immunologically demonstrated, a feature usually seen in in situ carcinomas. Therefore, it appears that the study of BL and myoepithelial cells should be added to pattern recognition in the diagnosis of these lesions.