Pancreatic neuroendocrine tumors (PanNETs) frequently use the alternative lengthening of telomeres (ALT) pathway for telomere maintenance. ALT is strongly correlated with α thalassemia-mental retardation, X linked (ATRX), and death domain-associated protein 6 (DAXX) alterations and a poor prognosis in patients with primary PanNET. Because fine-needle aspiration (FNA) is a noninvasive way to sample tumors, the authors evaluated whether they could accurately detect ALT and loss of ATRX/DAXX in a primary PanNET cohort of FNAs.