Adenoid Cystic Carcinoma of the Breast: Clinical and Radiological Findings.

Background/

Objectives

Breast adenoid cystic carcinoma (ACC) is a rare tumor with limited data on imaging features and treatment response. This study investigated the clinical and radiological characteristics of ACC of the breast.

Methods

Patients with ACC who underwent surgery at our institution between February 2010 and December 2023 were included. Clinical characteristics, biopsy and surgical pathology findings, and follow-up outcomes were reviewed. Preoperative mammography, ultrasound (US), and MRI findings were analyzed.

Results

Twenty-eight women (mean age, 57 ± 8 years) were identified. Half presented with palpable masses, and the remainder were detected on screening. Percutaneous biopsy was performed in 27 patients, correctly diagnosing ACC in 18 (66.7%), whereas 9 (33.3%) were misdiagnosed as having invasive ductal carcinoma. The mean tumor size was 2.9 cm (range, 0.9-8 cm), with axillary metastasis in two women (7.1%). Most tumors were triple-negative (78.6%), while six showed low estrogen-receptor positivity (<10%). Ki-67 was <20% in 64.3%, with no high values (≥75%). Three patients received neoadjuvant chemotherapy, with two non-responders. No recurrences occurred during a median follow-up of 51 months. Imaging revealed masses on mammography (85.2%), US (92.9%), and MRI (92.3%), with calcifications in two cases. Most lesions were highly suspicious (BI-RADS 4C or 5) and showed increased vascularity in 92.3% on Doppler US.

Conclusions

Breast ACC typically presents as a hypervascular, highly suspicious mass. Despite frequent triple-negative profiles, it shows low proliferation, poor response to chemotherapy, and favorable prognosis.