Solid-basaloid variant of adenoid cystic carcinoma of the breast unresponsive to neoadjuvant chemotherapy: Case report.

Introduction And Importance: Adenoid cystic carcinoma (ACC) is a rare triple-negative breast cancer, accounting for only 0.1 % of all primary breast carcinomas. At variance with the classic variant, the solid-basaloid variant of ACC (SB-ACC) is clinically more aggressive and has different molecular features. There is, currently, no consensus regarding the treatment of SB-ACC of the breast, especially the use of neoadjuvant chemotherapy.

Case Presentation: Here, we present a rare case of SB-ACC in an elderly female patient, with no history of breast carcinoma, who presented with a 4.5 cm central round mass invading the nipple. Given the locally advanced triple negative breast cancer and the invasion of the nipple-areolar complex, the patient has received neoadjuvant chemotherapy followed by surgical treatment. On histopathological examination, the diagnosis of SB-ACC, non-responsive to neoadjuvant chemotherapy, with absence of rearrangement of the MYB gene was retained. The patient received adjuvant radiation therapy and was ambulatory followed without recurrence at the 12-month follow-up.

Discussion/conclusion: This case provided direct evidence that SB-ACC of the breast wasn't responsive to neoadjuvant chemotherapy but cannot allow for definitive conclusions on chemotherapy recommendations. For this reason, more data must be published to investigate the real value of neoadjuvant chemotherapy in SB-ACC.