Secretory breast carcinoma: a clinicopathological and immunophenotypic study of 15 cases with a review of the literature.

Secretory breast carcinoma is a rare breast cancer with indolent clinical behavior. Recent research showed that secretory breast carcinoma belongs to the phenotypic spectrum of basal-like breast carcinomas. In this study, a clinicopathological and immunophenotypic analysis of secretory breast carcinomas from 15 Chinese patients was conducted. This patient group consisted of 2 males and 13 females, with ages ranging from 10 to 67 years old (median, 36 years old). All patients presented with a painless and firm mass. Tumor size ranged from 10 to 55 mm. Most tumors were located in the outer upper quadrant of the breast. Two patients (2 of 13, 15%) displayed positive axillary lymph nodes. At the microscopic level, the presence of intracellular and extracellular secretory material was the most remarkable feature. Most cases showed mild dysplasia cytologically. All cases were negative for estrogen receptor, progesterone receptor and HER2. The expression rate of the basal-like marker (CK5/6 or epidermal growth factor receptor) was 87% (13 of 15). The basal-like phenotype was identified in 13 cases (87%). Follow-up time ranged from 10 to 55 months (median, 19 months). None of the cases had evidence of recurrence and metastasis. Our study reveals that secretory breast carcinoma is a distinct subset of invasive breast carcinoma, with expression of basal-like markers. It should be noted that secretory breast carcinoma is different from conventional basal-like breast carcinomas. Future studies are required to further understand the prognostic significance of the basal-like markers expression in secretory breast carcinomas.