Spectrum of Special Variants of Breast Carcinoma and Differentiated Ductal Carcinomas with their Immunohistochemistry Profile in a Tertiary Care Centre

Background: Breast cancer is a diverse disease with varying characteristics in morphology, presentation, treatment, and prognosis. It constitutes 25% of cancers in Indian women. This study delves into rare special variants and differentiated ductal carcinomas, focusing on their unique histological features and molecular profiles. Aim: To scrutinize the spectrum of special forms of breast carcinoma and their immunohistochemistry (IHC) profile. Material and methods: A retrospective analysis of all the breast carcinomas over a period of 11 months was carried out. The clinical, gross, microscopic and immunohistochemistry findings of 15 special variants and differentiated ductal carcinomas were noted down. Results: In a retrospective analysis of 50 cases of breast carcinoma, 15 were diagnosed as special variants of breast malignancy which accounted to be 30%. Out of the 21 rare histologic subtypes of breast carcinoma 10 variants were encountered by us that included mucinous carcinoma, lobular carcinoma, papillary carcinoma, invasive breast carcinoma with medullary pattern, invasive breast carcinoma with oncocytic pattern, metaplastic carcinoma, cribriform carcinoma, malignant adenomyoepithelioma, secretory carcinoma, and invasive breast carcinoma with neuroendocrine differentiation. Conclusion: This study provides a comprehensive overview of the gross and microscopic features, as well as the immunohistochemistry profiles of these special variants and differentiated ductal carcinomas of the breast. We anticipate that this research will enhance our understanding of these uncommon breast cancer variants, with a particular emphasis on their molecular characteristics, contributing to improved management strategies in the future. Keywords: Breast Cancer, Immunohistochemistry, Molecular Classification