Evaluation of Tru-Cut biopsy in differential diagnosis and challenges in breast adenoid cystic carcinoma on a case basis

Adenoid cystic carcinoma (AdCC) is a very rare low-grade invasive carcinoma primarily in the breast. The fact that similar patterns can be observed in invasive breast carcinomas (IВC) such as AdCC and breast ductal carcinoma in situ (DCIS) in Tru-Cut biopsies creates difficulties in the differential diagnosis. Case presentation. A 70-year-old female patient was admitted to our outpatient clinic with the complaint of a palpable mass in the left breast subareolar region. In the light microscopy examination of 3 tissue samples with a size of 3 measurements, IBC-like tubular structures, some of which were formed by tiny uniform cells with narrow cytoplasm, and some with eosinophilic material, and solid nest structures suggesting DCIS in focal areas were observed. Immunohistochemical examination showed continuity of myoepithelial cells with p63 and calponin, and epithelial cells, staining with Cd117 and CK7. No staining was observed with progesterone, estrogen, and Cerbb2. The staining rate of Ki-67 was determined as 2 percent. A diagnosis of AdCC was made with these findings. Conclusions. It is important to search for different patterns in addition to double cell population and pay attention to the material in the lumens in breast Tru-Cut biopsies that contain AdCC patterns that may cause the diagnosis of IBC and DCIS in error. © 2022, Zaporizhzhia State Medical and Pharmaceutical University. All rights reserved.