ETV6–NTRK3 gene fusion in a secretory carcinoma of the breast of a male-to-female transsexual

Secretory carcinomas of the breast were first described as “juvenile carcinoma” by McDivitt and Stewart in a cohort of children. This term has been replaced by the term “secretory breast carcinoma”, because the entity can occur at any time of life. Carcinoma of the male breast is uncommon and accounts for approximately 1% of all cancers in men. Recently, it has been reported that human secretory breast carcinoma expresses the ETV6–NTRK3 gene fusion that was previously cloned in pediatric mesenchymal cancers. We present the case of a 46-year-old male-to-female transsexual in whom a secretory breast carcinoma was an incidental finding. As confirmation of the histopathological diagnosis we detected the novel ETV6–NTRK3 gene fusion in this tumor.