“Histomorphology of immunomodulation and PD1 expression in breast cancer tumor draining lymph nodes

Abstract

Abstract Background: Metastasis in tumor draining lymph nodes (TDLNs) is correlated with poor prognosis in breast cancers. It is associated with local immune suppression, which can be partly due to higher expression of immune check point receptors in immune cells. The morphological manifestation of underlying immune modulation of TDLNs has been less investigated. Here in, we present histomorphological changes and PD1 expression pattern in matched metastatic and non-metastatic TDLNs in breast cancer patients. Method: A total of 248 metastatic or non-metastaticTDLNs from 50 breast carcinoma samples were analyzed in the present study. Immune response in these TDLNs were assessed as per histomorphological patterns on H&E stained slides, categorizing them into lymphocyte predominance, germinal center predominance and an unstimulated pattern. Anti-PD1 immunohistochemistry was done on all lymph nodes. Results were analyzed using SPSS version 23 and p value <0.05 has been considered as significant. Results: The lymph node metastasis in breast carcinoma was significantly higher in older age, higher tumor grade and presence of lympho-vascular invasion in primary tumor. The metastatic lymph nodes showed high densities of germinal centers with abnormal shapes. There was significantly higher expression of PD1 in immune cells of metastatic TDLNs. Conclusion: The identification of specific immunohistochemical profile and histological changes of TDLNs should therefore be considered as possible prognostic and predictive markers for lymph node metastasis. The patients with higher densities of germinal center with abnormal shape and increased PD1 expression should benefit from immune-check point inhibitor therapy.

Keywords

• Tumor draining lymph nodes (TDLN), histology, PD1 immunohistochemistry, breast carcinoma