Whole-exome Sequencing of Epstein-Barr Virus-associated Pulmonary Carcinoma With Low Lymphocytic Infiltration Shows Molecular Features Similar to Those of Classic Pulmonary Lymphoepithelioma-like Carcinoma: Evidence to Support Grouping Together as One Disease Entity.

Abstract

Pulmonary lymphoepithelioma-like carcinoma (LELC) is a distinct type of Epstein-Barr virus (EBV)-associated non-small cell carcinoma characterized by a syncytial growth pattern with heavy lymphocytic infiltration. We recently identified a group of non-small cell carcinomas, which are also associated with EBV but lack significant lymphocytic infiltration. These EBV-associated pulmonary carcinomas with low lymphocytic infiltration morphologically resemble nonkeratinizing squamous cell carcinoma, but their patient characteristics are more similar to those of LELC, including female sex and nonsmoking status. To clarify the relationships between these disease entities, in this study, we explored the molecular characteristics of the EBV-associated carcinomas with low lymphocytic infiltration using whole-exome sequencing and compared their molecular profiles with those of classic LELC and pulmonary squamous cell carcinoma. We demonstrate that the molecular characteristics of EBV-associated carcinomas with low lymphocytic infiltration are highly similar to those of classic LELC. Both show low tumor mutational burden, lack of commonly mutated driver genes in other types of non-small cell lung cancer, similar mutational signature involving APOBEC-related mutations, and enrichment of CD274 (programmed death-ligand 1) amplification. These molecular characteristics are very different from those of pulmonary squamous cell carcinoma. The unique patient demographics and molecular characteristics shared by EBV-associated carcinomas with low lymphocytic infiltration and classic LELC suggest that these tumors represent one single disease entity defined by EBV association. This study supports the proposal for the usage of the term "EBV-associated pulmonary carcinoma" to encompass the entire morphologic spectrum of this distinct EBV-associated disease entity.