CD274 and breast neoplasm: A similar upregulation of PDL1 was not observed in the lymph node bearing metastatic breast tumor, although this may be due to the existence of other immune regulatory pathways in the lymph node or be attributed to the different tissue types being characterized (metastasized breast tumor vs healthy lymphoid tissue), or to the presence of activated leukocytes within the lymph node in response to antigen draining from the distal tumor, which can express PD-L1 in some conditions and therefore mask the final result [33, 34].