The authors detected PD-L2 expression in tissues associated with Barrett’s esophagus and reported a potential association of the inflammatory environment in Barrett’s esophagus and PD1 ligand expression.30 A potential limitation of this study was the use of tissue microarrays instead of whole tissue slides, especially because esophageal adenocarcinomas are highly heterogeneous.31,32 Consequently, several important areas of the tumor might have been missed with analyses limited to microarray-based tissue cores. The gene discussed is PDCD1LG2; the disease is Barrett esophagus.