A Spectrum of Histopathological Changes in Invasive Ductal Carcinoma of Breast Following Neoadjuvant Chemotherapy: A Tertiary Care Center Study.

Abstract

Background: Neoadjuvant chemotherapy (NACT) induces characteristic morphological changes in breast carcinoma, which are crucial for assessing treatment effect and distinguishing residual tumor from therapy-related changes.
Objective: To describe the spectrum and frequency of cellular and stromal histopathological changes in invasive breast carcinoma following NACT in a tertiary care setting.
Materials and Methods: This cross-sectional study included 60 post-NACT mastectomy specimens from patients with invasive ductal carcinoma (IDC). Pre- and post-chemotherapy H&E-stained slides were compared. Cellular changes (pyknosis, karyorrhexis, karyolysis, cytoplasmic vacuolation, multinucleation) and stromal changes (fibrosis, hyalinization, calcification, necrosis, lymphocytic infiltration, etc.) were systematically evaluated using defined criteria. Masson’s Trichrome stain was used to assess fibrosis.
Results: Cytoplasmic vacuolation was the most prevalent cellular change, observed in 81% of cases with viable tumor. Nuclear pyknosis and karyorrhexis/karyolysis were seen in 78.3% and 75.7% of cases, respectively. Multinucleation was noted in 24.3% cases. The predominant stromal alteration was fibrosis (100%). Among this widespread fibrosis was present in 85% of all cases. Other common stromal changes included hyalinization (86.7%), minimal lymphocytic infiltration (56.7%), and degenerative changes (58.3%). Infiltration of foamy macrophages and hemosiderin-laden histiocytes was observed less frequently.
Conclusion: NACT induces a consistent and recognizable spectrum of histopathological changes in breast cancer. Widespread fibrosis and cytoplasmic vacuolation are the hallmark features. Recognizing these alterations is essential for accurate post-chemotherapy evaluation and avoiding diagnostic pitfalls particularly in resource-limited tertiary care settings.

KYAMC Journal Vol. 16, No. 04, January 2026: 202-207.