Rekhtman N, et al. - The purpose of this trial was to investigate the expression of exocrine marker napsin A, along with TTF-1, in large cell neuroendocrine carcinoma (LCNEC). It also performed a clinicopathologic and genomic assessment of napsin A-positive cases. The data presented that LCNECs were rare among lung neuroendocrine neoplasms, as some of these tumors illustrated low-level expression of exocrine marker napsin A, and harbored genomic alterations typical of adenocarcinoma. Irrespective of the apparent close biological correlation, designation of adeno-like LCNEC as a separate entity from adenocarcinoma was validated by their distinctive morphology, typically diffuse expression of neuroendocrine marker(s) and aggressive behavior.