Basaloid ductal carcinoma in situ arising in salivary gland metaplasia of the breast: a case report

Salivary gland metaplasia is a newly recognized, adenosis-like lesion which could not be classified according to known categories of adenosis of the breast. We report a case of basaloid ductal carcinoma in situ (DCIS) arising in a background of salivary gland metaplasia in a 49-year old woman who visited our hospital for a right breast mass. Breast ultrasonography showed a multi-lobulating mixed hypoechoic and isoechoic mass measuring 2.9 cm in size at the periareolar area. Histologically, the lesion showed a well-defined DCIS with basaloid tumor cells and central comedo-type necrosis surrounded by salivary gland metaplasia composed of glands or ducts not specific to the breast, ducts with cribriform proliferation of luminal epithelial cells, and ducts with varying degrees of proliferation of basaloid cells including solid nests of basaloid cells. Salivary gland metaplasia is a most unusual lesion of the breast characterized by salivary gland-type acini and ducts with various proliferations of luminal and basaloid cells, and accompanied by malignant tumor of basal cell type.