Terra SBSP, et al. - Resected pulmonary carcinoid tumors (PCT) (1997-2017) were analyzed in order to examine alpha-thalassemia/mental retardation syndrome X-linked (ATRX) expression in PCT and its diagnostic and prognostic role in these people. Whilst adjusted for lymphovascular invasion and perineural invasion, loss of ATRX expression was related to atypical PCTs. Following adjusting for lymphovascular invasion and the presence of metastatic disease at the time of diagnosis, loss of ATRX expression was correlated with shorter disease-specific survival. Via two reviewers, interobserver agreement on ATRX expression was important. Thus, ATRX expression is more generally lost in atypical vs typical PCT and is related to more aggressive tumor features and shorter disease-specific survival.