[Mammary carcinoma arising in microglandular adenosis: a case report].

Microglandular adenosis is an uncommon benign breast entity considered as a variant form of adenosis. The diagnosis is frequently made by the pathologist as it is often clinically asymptomatic. Carcinoma arising in microglandular adenosis is very uncommon. We report a case of carcinoma arising in microglandular adenosis in a 54-year-old woman. The immunohistochemical profile, especially S100 protein expression and absence of epithelial membrane antigen, was useful to recognize the microglandular adenosis and the carcinoma of alveolar architecture, while invasion was suggested by the basement membrane disruption highlighted with anti-collagen IV immunostaining. The good prognosis of carcinoma associated with microglandular adenosis points out the importance of distinguishing this lesion from other breast carcinomas.