Programmed Death Ligand 1 Expression in Lung Adenocarcinoma: An Analysis of the Histomorphological Features.

Abstract

Immunotherapy is now a vital target therapy in the advanced cases of lung adenocarcinoma. The outstanding result of therapies with medications that inhibit the interaction of programmed death ligand 1 with programmed death protein 1 has revolutionarized prognostic treatment regimes. The study was undertaken with the objectives to analyze the detailed histomorphological features of adenocarcinoma lung with programmed death ligand-1 (PD-L1) expression in tumor cells and to compare the histomorphological features with PD-L1 negative group. The present study is a retrospective case series with 100 cases of non-small cell lung cancer-adenocarcinoma phenotype in which testing for PD-L1 had been done using immunohistochemistry. Detailed histomorphological analysis and comparison was performed for both the PD-L1 positive and negative phenotype. Histomorphological features of 25 cases with positive PD-L1 positivity in the tumor cells and 75 cases that were negative for PD-L1 were analyzed. The most frequent pattern in the category that was PD-L1 positive was singly scattered cells or loose clusters present in 84% cases followed by solid nests that was identified in 60% cases. The presence of solid nests in the PD-L1 positive category was statistically significant (P = 0.018). Mucin was identified in 24% cases, and tumor necrosis was documented in 60% cases with PD-L1 positivity. In the cluster that was PD-L1 positive, 92% cases had moderate-to-severe nuclear pleomorphism. The identification of histomorphological patterns and characteristics may aid in triaging cases that have the likelihood to harbor PD-L1-positive phenotype, which has predictive and prognostic outcome.