Adenoid cystic carcinoma of the breast with aggressive behavior: A case report and review of the literature.

Adenoid cystic carcinoma (AdCC) of the breast is a subtype of triple-negative breast cancer characterized by a distinct indolent behavior, with extremely rare lymphatic involvement and a late onset of distant metastasis occurring several years post-diagnosis. Due to its favorable prognosis, therapeutic guidelines include surgical resection with adjuvant radiotherapy, with no significant benefit of chemotherapy. The present study discusses the case of a 77-year-old female patient who presented with a right-sided breast mass. Biopsy confirmed a grade 2 AdCC transitioning to a higher grade in some areas. The patient underwent a wide local excision and adjuvant radiotherapy was planned; however, during a simulation computed tomography scan performed 6 weeks after surgery, a complex mass at the ipsilateral axillary tail was detected and proved to be disease recurrence on biopsy. Restaging imaging studies showed metastatic involvement of the regional lymph nodes, lungs, liver, bones and brain. The patient received three cycles of palliative chemotherapy, but then clinically deteriorated and passed away 7 months after the initial diagnosis. Notably, the relatively large tumor size (6.4 cm) and the presence of high-grade morphology may have contributed to the poor outcome of the patient. In addition, the current case is one of the unique reported instances in the literature where the interval between treatment and recurrence was <3 months, as well as being one of the few cases that exhibited lymphatic involvement. The present report underscores the importance of further understanding the variable presentations of AdCC.