Terra SBSP, et al. - Given a link between loss of alpha thalassemia/mental retardation syndrome X-linked (ATRX), a chromatin regulator, and worse prognosis in pancreatic neuroendocrine tumors, researchers explored ATRX expression in pulmonary carcinoid tumors (PCT) as well as inquired about its diagnostic and prognostic role in these patients. They reviewed resected PCTs (1997-2017). In a study sample of 115 patients with 69 (60%) typical and 46 (40%) atypical PCTs, a link was identified between loss of ATRX expression and atypical PCTs when adjusted for lymphovascular invasion and perineural invasion. Atypical PCT was predicted by ATRX expression, with sensitivity, specificity, and AUC of 37%, 92%, and 0.62, respectively. Shorter disease-specific survival related to loss of ATRX expression was reported after adjusting for lymphovascular invasion and the presence of metastatic disease at the time of diagnosis. Findings revealed that in atypical vs typical PCT, ATRX expression was more commonly lost. More aggressive tumor features and shorter disease-specific survival were reported in correlation with ATRX expression.