CARCINOMA IN-SITU INVOLVING SCLEROSING ADENOSIS - A MIMIC OF INVASIVEBREAST-CARCINOMA

The distinction between invasive and in situ carcinoma of the breast i s important with regard to the treatment and prognosis of the patient, When carcinoma in situ involves breast tissue in which the normal arc hitecture is altered by pre-existing sclerosing adenosis, the resultin g histological picture may closely mimic an invasive carcinoma. We rec ord the histopathological features in 13 cases where there was difficu lty in identifying the presence or extent of invasive carcinoma, The m ost useful due was attention to the low power appearances of distorted lobular units in the areas of malignancy and comparison with surround ing breast tissue which usually showed recognizable sclerosing adenosi s, The use of immunohistochemical stains for myoepithelium (alpha-acti n and S-100 protein) and for basement membrane (collagen type IV and l aminin) proved to be of considerable value in identifying the preserva tion of these features around glandular structures in areas of scleros ing adenosis containing in situ carcinoma.