Clinicopathological Insights of Rare Breast Carcinoma with Characteristic Diagnostic Features of Medullary Breast Cancer: A Comprehensive Literature Review

Abstract

Medullary breast carcinoma (MBC) is a rare histological subtype of invasive breast cancer, accounting for less than 5% of all breast malignancies, and presents with a unique clinical paradox. Despite its aggressive histopathological features such as high-grade nuclei, prominent lymphoplasmacytic infiltration, and syncytial growth patterns, it often demonstrates a more favorable prognosis compared to other high-grade breast cancers, particularly invasive ductal carcinoma (IDC). This paradox has drawn significant interest in understanding its unique biological behaviors. It bears varying morpho-pathological and immunological resemblance to medullary-like carcinoma, oligodendrogliomas, seminoma, dysgerminoma, hairy cell leukemia, and breast cancers like Basal-like breast carcinomas (BLBCs). MBC is frequently triple-negative, lacking expression of estrogen receptor (ER), progesterone receptor (PR), and HER2/neu, which limits the applicability of targeted hormonal or HER2-directed therapies. However, the presence of dense immune infiltration and associations with BRCA1 mutations suggest potential responsiveness to immunotherapy and DNA-damage targeting strategies. A better understanding of its underlying biology may pave the way for a more effective, individualized treatment options and improved clinical outcomes. The review explores clinicopathological characteristics, diagnostic challenges, and molecular profile, while serving as a one-stop narrative review for medical students and residents to learn the evolving template in the therapeutic approaches in the management of MBC.