Adenoid cystic carcinoma of the breast: report of the diagnosis and management of two cases.

Introduction and importance: Clinical data on breast adenoid cystic carcinoma (ACC) remain limited, and management strategies are not well defined. In this article, we present two cases of breast ACC that were managed at a tertiary care hospital. Presentation of case: The first patient, a 42-year-old woman, was referred to our clinic due to cyclical left breast pain and a palpable mass in the left breast. Mammography did not reveal any masses; however, bilateral breast MRI with and without contrast identified a suspicious mass in the left breast, raising concern for malignancy. Immunohistochemical (IHC) analysis of the specimen showed triple-negative status for ER, PR, and HER2. The patient underwent a partial mastectomy without axillary lymph node dissection, followed by Grisotti flap reconstruction. Histopathological examination of the excised mass confirmed the diagnosis of ACC. The second patient, a 49-year-old woman, was initially diagnosed with invasive ductal carcinoma on the basis of a core needle biopsy and had undergone eight cycles of chemotherapy without any improvement. Mammography revealed a spiculated 17 mm mass in the upper outer quadrant of the right breast. Breast ultrasound detected a hypoechoic mass with irregular borders on the lateral side of the right breast, categorized as BI-RADS 4. IHC confirmed that the mass was triple-negative. She underwent a lumpectomy, and histopathological examination of the excised mass confirmed the diagnosis of ACC. Discussion: ACC can be misdiagnosed as other types of breast cancer when clinical awareness is insufficient, potentially leading to unnecessary chemotherapy and inappropriate treatment. Using a combination of imaging modalities may improve diagnostic accuracy and facilitate earlier detection. Conclusion: Our study contributes to the existing literature by offering additional insights into the clinical characteristics and management strategies of breast ACC.