Divergence and heterogeneity of neoplastic PD-L1 expression: Two autopsy case reports of intravascular large B-cell lymphoma.

Intravascular large B-cell lymphoma (IVLBCL) is a distinct disease, but the neoplastic PD-L1 expression on tumor cells may vary among cases. We evaluated 10 IVLBCL autopsy cases for neoplastic PD-L1 expression, and had positive results in two cases. In one case, neoplastic PD-L1 expression (SP142, 28-8, and E1J2J clones) was dependent on the organ and anatomical site (capillaries vs. vessels) of the tumor tissue. Neoplastic PD-L1 expression was found in tumor cells located in capillaries in the central nervous system, pituitary gland, kidneys, lung, and gastrointestinal tract; sinuses/sinusoids of the spleen, liver, bone marrow, and lymph nodes; and an extravascular location. However, this expression was not detected in tumor cells located in the adrenal gland, thyroid gland, pancreas, ovaries, uterus, pleura, and small or larger-sized vessels of the lung. The other case showed constant neoplastic PD-L1 expression on the tumor cells, and in addition to the affected organs, capillaries, and vessels with two anti-PD-L1 antibodies (28-8 and E1J2J, but not SP142). The divergence and heterogeneity of neoplastic PD-L1 expression were clearly demonstrated in our cases. To the best of our knowledge, this is the first description of divergent neoplastic PD-L1 expression among the affected organs and anatomical sites in IVLBCL.