Invasive lobular carcinoma of the breast: cytometric and immunohistochemical characteristics of 96 cases.

The aim of the study was to present microscopic, cytometric and immunohistochemical characteristics of a group of 96 invasive lobular carcinomas (ILC) of the breast. Ninety six patients treated surgically at the Department of Surgical Oncology, Centre of Oncology - Maria Skłodowska-Curie Memorial Institute, Cracow Branch, between 1983 and 1996, were included into the study. In 56 (58.3%) cases, a classical pattern of ILC was diagnosed, whereas atypical variants (solid, pleomorphic, pleomorphic with signet ring cells, signet ring cell, and tubulolobular) were recognized in 40 (41.7%) cases. ILC was characterized by lack of E-cadherin expression, high rate of steroid receptor expression, low rate of P53 and c-erb-B2 expressing tumours, low MIB-1 labelling index, and low S phase fraction, as well as high rate of diploid lesions.