Singh L, Singh MK, Rizvi MA, et al. - In the present study, the researchers sought to examine the expression of the programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), CD4 and CD8 proteins and their prognostic value in the tumour microenvironment of sebaceous gland carcinoma (SGC). The expression levels of PD-1, PD-L1, CTLA-4, CD4 and CD8 proteins were evaluated in 52 cases of SGC by immunohistochemistry and validated by western blotting. In tumour cells, the expression of PD-L1 was found to be higher than in stromal cells. The prognostic outcome of PD-1 and PD-L1 protein expression in cells of tumour–stromal compartments was highlighted in this analysis. Such findings suggest that the PD-1/PD-L1 pathway mediates essential interactions within the tumour microenvironment in SGC.