Fig. 2

Immune Profiling of Metastatic Lesion. Metastatic pancreatic adenocarcinoma showing loss of MLH1 and PMS2 and increased immune cell infiltration. H&E section demonstrates a gland forming adenocarcinoma, morphologically compatible with pancreatic origin (a). By immunohistochemistry, the tumor cells show loss of staining for MLH1 (b) and PMS2 (c) and retained staining for MSH2 (d) and MSH6 (e). The tumor cells are also negative for PAX8 (f), in keeping with its non-Mullerian origin. Assessment of immune cell infiltration demonstrates florid CD8 positive T cells infiltrating the tumor epithelium and in the stroma surrounding the tumor epithelium (g). There is also prominent PD-1 positive immune cells (h) distributed similarly as the CD8 positive cells. PD-L1 expression is focally present in immune cells and in some tumor cells (i)