Invasive Breast Carcinoma of No Special Type with Medullary Pattern: Morphological and Immunohistochemical Features.

Objective: Our study investigated the morphological and immunohistochemical characteristics of invasive breast carcinoma of no special type (IBC-NST) with medullary pattern to explore the inconsistencies between the structural and clinical traits of this category of tumor.

Material And Method: The breast carcinoma samples (n = 26) with medullary pattern (defined according to established criteria) were subjected to immunohistochemical assays of the following receptors: ER, PR, HER2/neu, Ki-67, p53, Bcl-2, VEGF, MMP1, E-cadherin, EGFR, Hsp70, Hsp90, CD20, CD3, CD4, CD8, CD68, CD163, CD56, CD138, MPO, S100, IgG, IgM, and PD-L1.

Results: IBC-NST with medullary pattern was found to have negative expression of ER, PR, and HER2/neu; strong positive expression of Kі-67, mutant р53, Bcl-2, E-cadherin, EGFR, and PD-L1; moderate positive expression of Hsp70 and Hsp90; and low or negative expression of VEGF and MMP1.