1 Introduction Secretory breast carcinoma(SBC) is a rare(＜ 1％) type of breast carcinoma,which was initially termed "Juvenile breast cancer" by McDivitt and Stewart,based on the fact that the average age of the 7 patients described in their report was 9 years old with a range of 3 to 15 years[1].It is most common under the age of 30,and it is the most common type of breast carcinoma in children[2].Although firstly described in children and adolescents,it is now known to occur in adults of both sexes[3],and male to female ratio is 1:6[4].The tumor is the only epithelial tumor of the breast with a balanced translocation,t (12;15),that creates an ETV6-NTRK3 gene translocation[3].The biological consequence of this translocation is the fusion of the dimerization domain of a transcriptional regulator (ETV6)with a membrane receptor tyrosine kinase (NTRK3) that activates the RasMekl and PI3K-Akt pathways which are important for breast cell proliferation and survival.This specific translocation is associated with congenital fibrosarcoma and mesoblastic nephroma,2 morphologically similar pediatric mesenchymal tumors with no epithelial features[5].
