Plasmablastic Lymphomas: Characterization of Tumor Microenvironment Using CD163 and PD-1 Immunohistochemistry.

Area of Science:

• Oncology
• Immunology
• Pathology

Background:

• Plasmablastic lymphoma (PBL) is an aggressive B-cell neoplasm.
• The tumor microenvironment (TME) significantly influences cancer progression.
• Tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs) are key immune components in the TME.

Purpose of the Study:

• To characterize the TME of PBL by quantifying CD163(+) TAMs and PD1(+) TILs.
• To review the role of the PD-1/PD-L1 pathway in hematopoietic neoplasms.
• To explore potential mechanisms and future research directions.

Main Methods:

• Immunohistochemical analysis of CD163 and PD1 in 11 PBL cases.
• Quantification of positive TAMs and TILs percentages.
• Classification of cases into high/low TAMs and TILs based on established cutoffs (≥30% and >5%, respectively).

Main Results:

• A majority of PBL cases (73%) exhibited high TAMs.
• A minority of cases (27%) showed high TILs.
• A trend towards negative correlation between TAMs and TILs (p=0.08) was observed, with a predominant TAM-high/TIL-low pattern (63%).

Conclusions:

• PBL TME typically shows high TAMs and low TILs.
• Further studies are needed to clarify the clinical significance of TILs and the impact of EBV/HIV.
• Investigating PD-L1 expression in PBL is warranted due to its association with TAMs in other malignancies.