Invasive cystic hypersecretory carcinoma of the breast: a case report.

Cystic hypersecretory lesions of the breast are rare. These breast lesions include cystic hypersecretory hyperplasia (CHH), atypical CHH, and cystic hypersecretory carcinoma (CHC). The characteristic features are dilated ducts and cysts filled with thyroid colloid-like eosinophilic secretion. Only seven cases of invasive CHC have been reported in the literature. Here, we report an additional case of invasive CHC. The histologic features of the tumor showed both micropapillary intraductal carcinoma and focal high-grade invasive carcinoma in a background of CHH. This case suggests that cystic hypersecretory breast lesions encompass a spectrum of pathologic lesions including CHH, atypical CHH, CHC, and invasive CHC.