Secretory Carcinoma of the Breast With Multiple Distant Metastases in Brain and Unfavorable Prognosis: a Case Report and Literature Review

Background: Secretory carcinoma of the breast is one of the rarest entities accounting for less than 0.15% of all infiltrating breast carcinomas. It has characteristic histopathological and molecular features and more favorable prognosis. In this case report, we describe a local advanced secretory carcinoma of the breast with chemo-resisted for neoadjuvant chemotherapy and unfavorable prognosis.Case Presentation: A hard, painless and palpably bossed mass about 12 cm in diameter occupied most of the left breast of a 39-year-old woman and fixation to the overlying skin. Breast ultrasonography and magnetic resonance imaging (MRI) scan gave the same grading as BI-RADS IV. A needle biopsy was performed and pathological diagnosis was secretory carcinoma. Neoadjuvant chemotherapy (NAC) was then performed, after which ultrasonography and MRI scan revealed the tumor was partial response for EC therapy while progressive disease after the DC therapy. The tumor showed chemo-resisted for neoadjuvant chemotherapy. Left breast mastectomy and axillary lymphadenectomy were subsequently performed. Tumor cells were triple-negative and positive for S-100 and periodic acid-Schiff (PAS) staining. Fluorescence in-situ hybridization (FISH) analysis indicated the fusion arrangement of ETV6-NTRK3 gene. The patient underwent multiple distant metastases in brain, and died of these metastases 19 months after initial diagnosis.Conclusion: Secretory carcinomas of breast have been described as a low-grade histologic subtype with a favorable prognosis. This case showed chemo-resisted for neoadjuvant chemotherapy, multiple distant metastases, and final an unfavorable prognosis. Further research is needed to better understanding of its behavior and treatment of this rare tumor.