Association of breast carcinoma and multiple intraductal papillomas: an histological and immunohistochemical investigation.

To identify histological preneoplastic lesions and early neoplastic foci, a histological and immunohistochemical study has been conducted on a series of 18 cases with the rare association of multiple intraductal papillomas and in situ breast carcinoma. The pathological and clinical data of these cases have been collated. A close anatomical and spatial association between the benign papillomas and areas of in situ carcinoma (mostly of the cribriform type) was a frequent finding. In agreement with the results of our previous investigations, cytoplasmic CEA has been found to be a marker of intraductal carcinomas, while staining for actin has been found useful to identify the myoepithelial cells present in benign papillomas as opposed to carcinomas. The immunohistochemical procedures for these two markers have been conducted on parallel sections; alternatively, an immunoperoxidase/immuno-galactosidase sequence has been applied on the same section. The results indicate that, in cases with multiple papillomas, CEA-positive, myoepithelial cell-free carcinomatous areas can be anatomically associated with and even present inside the benign-looking papillary lesions. These findings can be interpreted as evidence of a malignant transformation of intraductal papillomas, or, less likely, of their 'cancerization' by ductal carcinoma.