Adenoid cystic carcinoma (ACC) of the breast is a very rare neoplasm. It presents a triple-negative phenotype in most cases, but its prognosis is generally considered to be better than other breast cancers with the same immunohistochemical pattern. Due to its controversial features, no data are available in the literature regarding a consensus approach for ACC treatment, especially for subtypes with worse prognosis like solid basaloid ACC. We present for the first time a rare case of ACC with multifocal presentation treated with breast-conservative surgery and intraoperative electron radiotherapy, thus supporting this treatment of ACC in selected patients like young women affected by the solid basaloid variant who commonly present a worse prognosis. In this case, no local or systemic recurrence was detected after 30 months of follow-up.
Keywords: HIOB; IOERT; adenoid cystic carcinoma of breast; breast; breast-conservative surgery; solid basaloid adenoid cystic carcinoma of breast; special type breast carcinoma; triple-negative breast cancer.
Plain language summary Breast cancer is a large group of tumors with different and specific features. Because of its variety, no univocal guidelines are available to medical doctors for the treatment of this disease, especially for the rarest presentations. This is the case for breast adenoid cystic carcinoma, a rare tumor which accounts for less than 0.1% of all breast cancers and about which few instructions for its therapeutic approach or prognosis are described in the literature. This case report describes our experience using partial breast resection in combination with a specific protocol of intraoperative radiation for the treatment of an aggressive variant of breast adenoid cystic carcinoma. Good cosmetic results and no recurrence of the disease were shown, suggesting that a conservative approach could avoid unnecessary total breast resection as supported by some previous authors.