Histological Characterization of Carcinoma In Situ and Benign Lesions Associated with Metaplastic Carcinoma of the Breast.
Angelo Rodrigues, Conceicao Leal. Instituto Português de Oncologia do Porto Francisco Gentil, EPE, Porto, Portugal
Background: Metaplastic carcinomas (MC) of the breast comprise a rare but heterogeneous group of tumours, representing less than 1% of all breast cancers. In MC a variable portion of the tumor display a "metaplastic" phenotype ( either squamous, spindle/sarcomatous or matrix-producing). There are different classification schemes of MC and the prognostic correlation is not uniform. While the main focus of the literature concerning MC has been the categorization of the invasive components, there are some reports regarding the association with in situ carcinomas (CIS), ductal (DCIS) or lobular, cysts, papillomas and sclerosing lesions, which have not been fully accounted for. The aim of this study is to characterize the CIS and the benign mammary lesions associated with MC.
Design: 51 cases of MC, diagnosed between 1980 and September 2010, were retrieved and broadly categorized into one of the three following groups (according to the predominant component): squamous, spindle cell and matrix-producing. The cases were then screened for the presence of CIS and all the benign lesions present were also documented.
Results: All the patients were female, with a mean age of 63 years (25 – 99 years). The average tumour size was 4,5cm (0,3 – 23,5cm). CIS was found in 24 cases (47%), 23 (95,8%) of them were DCIS, 20 (83,3%) had high nuclear grade, and 12 (50%) cases presented with apocrine features. The distribution of CIS on the aforementioned groups is as follows: 17 cases (70,8%) in the spindle cell group; 5 (20,8%) in the squamous group and 2 (8,3%) in the matrix-producing group. In 14 (8 from the spindle cell group and 6 from the squamous group) cases, there was evidence of a cyst partially or completely involved by carcinoma. Concerning the benign lesions, columnar cell change was found in 26 cases (50,9%), ductal hyperplasia in 22 (43,1%, the majority of which were florid), micropapillomas in 9 (17,6%) and sclerosing lesions in 9 cases (17,6%).
Conclusions: DCIS is associated with MC of all types but more frequently in the cases with predominant spindle/sarcomatous component. A special association with the equally rare apocrine DCIS deserves further attention.
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 2, Tuesday Afternoon