Intraductal carcinoma of the breast arising in sclerosing adenosis.

An unusual case of intraductal carcinoma of the breast arising in sclerosing adenosis is reported. A 49 year old Japanese woman noticed a lump in her right breast 3 years before she sought medical advice. Histologic examination of the lumpectomy specimen showed, adjacent to intraductal papilloma, sclerosing adenosis involved in a neoplastic cellular proliferation with cribriform pattern and comedo necrosis. Immunohistochemical study with anti-actin antibodies discriminated intraductal carcinoma from adjacent sclerosing adenosis by highlighting myoepithelial components in the latter. Extensive sampling revealed no carcinoma outside the sclerosing adenosis, implying that the intraductal carcinoma did originate in the tubules of sclerosing adenosis. A review of the literature indicated that the ductal to lobular ratio among carcinoma in situ concurring with sclerosing adenosis is about 1:2. The average age of patients with ductal and lobular carcinoma in situ in sclerosing adenosis is 39 and 43.7, respectively. It is suggested that carcinoma in situ arising in sclerosing adenosis and fibroadenoma have a similar biological basis.