ETV6-NTRK3 Gene fusion positive Secretory carcinoma Breast in a two year seven month old child with metastatic axillary lymph node: A case report and Review of literature

Abstract Secretory breast carcinoma (SBC) is an exceptionally rare type of breast carcinoma accounting for less than 0.15% of all breast cancers6and with varied presentations. There is a lack of consensus regarding the exact management and there is evolving role of targeted therapy with successful treatment outcomes. We present a case of SBC in a two year seven month old child with axillary lymph node(ALN) metastasis, oestrogen receptor(ER) positivity and the characteristic ETV6-NTRK3 fusion gene expression. She was managed by surgery followed by use of tamoxifen and targeted agent Larotrectinib. Chemoradiotherapy was avoided considering the age and doubtful benefit. We also summarise the pattern of presentation in SBC, treatment options and follow up which would aid in making treatment decisions in clinical practice. Keywords: Breast, Secretory carcinoma, ETV6-NTRK3 fusion, Larotrectinib