Comparative Characterization of Lymphoid Infiltration in Different Molecular-Biological Subtypes of Invasive Breast Cancer.

The morphometric study examined the cell profile of lymphoid structures and leukocytic infiltrates in mammary glands of women with different molecular-biological subtypes of invasive breast cancer (BC). A high degree of lymphoid infiltration with the formation of lymphoid nodules was typical of luminal B (LumB) subtype of BC characterized by high tumor proliferation index (Ki-67≥30%) and in triple negative BC with Ki-67 ranging 33-35%. In these BC subtypes, extensive necrotic foci and pronounced stromal fibrosis of the mammary glands were observed. Lymphoid clusters and nodules predominantly consisted of B cells (CD20 ⁺ ) and T helper cells (CD4 ⁺ ). Cytotoxic lymphocytes (CD8 ⁺ ) were mostly observed in interstitial infiltrates. Macrophages and plasma cells were primarily located near the tumor cells. The presence of lymphoid clusters in the form of lymphoid nodules and dense lymphoid infiltrates can be viewed as unfavorable sign during diagnosis of BC and prediction of the course of the tumor process.