27. Secretory carcinoma of the breast: a case presentation and brief review

Background Secretory breast carcinoma is an extremely rare subtype of invasive ductal carcinoma, accounting for less than 0.15% of all breast cancers. It has characteristic morphologic features and is the only epithelial breast tumour with a specific translocation (ETV6-NTRK3). Despite being a low grade carcinoma, it has recently been found to be express basal markers and hence is part of the basal-like spectrum of breast cancer. Case presentation We present a case of secretory carcinoma in the left breast of a 52-year-old woman. The immunophenotype was ‘triple negative’ (i.e., ER, PR and HER2 negative) with expression of some basal markers (CK5/6, vimentin and S100). Conclusion This is a rare tumour and is the only case of secretory breast carcinoma diagnosed at our institution within the last 10 years. It is important to recognise that not all carcinomas with triple negative, basal cytokeratin positive phenotype have high grade morphology.