Lymphocyte-predominant triple-negative breast carcinomas in premenopausal patients: Lower expression of basal immunohistochemical markers

Abstract

Objectives: Triple-negative breast carcinomas (TNBCs) correspond to a molecular heterogeneous disease defined by lack of estrogen and progesterone receptor expression, and the absence of overexpression and/or amplification of HER2. Recent data indicate that clinical outcome in TNBC is affected by tumorinfiltrating lymphocytes, suggesting that they can benefit from immunotherapies. We selected 116 consecutive premenopausal patients with TNBC to compare the immunohistochemical profile of the group rich in tumor-infiltrating lymphocytes with those without this characteristic. Materials and methods: We reviewed all the original histological sections to assess pathological features, and to select a representative area for tissue microarrays and immunohistochemical study. Estrogen and progesterone receptors, HER2 and Ki-67 were evaluated in whole histological sections. The following markers were analyzed in tissue microarrays sections: androgen receptor, cytokeratin 5/6, cytokeratin 14, epidermal growth factor receptor (EGFR), vimentin, p16, claudin-3, -4, and -7, p63, and aldehyde dehydrogenase isoform 1 (ALDH1). Lymphocyte-predominant breast cancer (LPBC) was defined by the presence of more than 50% of lymphocytes in the intratumoral stroma. Results: Twenty-six (22.4%) patients present tumors classified as LPBC and 90 (77.6%) as non-LPBC. The two groups were similar regarding age of patients, tumor grade and Ki-67 positive cells. LPBC cases presented lower frequency of expression of the basal cytokeratins, EGFR, and basal-like immunoprofile. There was a trend to higher expression of ALDH1 by stromal intratumoral cells. The expression of all other markers were similar in the two groups. Conclusions: Lymphocyte-predominant TNBC in premenopausal patients are mostly of non-basal phenotype.