Adenoid cystic carcinoma of the breast.

Adenoid cystic carcinoma of the breast (ACC) is a rare tumor, comprising <0.1% of all breast cancers. It has a unique dual-cell pattern and is indistinguishable from ACC arising from salivary tissue. It is a low-grade tumor with favorable prognosis, and rare metastasis, with unique features. It is more commonly seen in older women with a mean age at diagnosis of 63, with Caucasian women being at greatest risk. Most cases present as a painful, palpable mass in the outer quadrants of the breast, and must be diagnosed via core needle biopsy or surgical excisional biopsy. Although few other cancers resemble ACC it is commonly misdiagnosed. Given the rarity of this cancer, treatment guidelines have yet to be well established. Current treatment is focused around surgical resection, however, there are not specific recommendations for the extent of resection due to the lack of cases to draw from.