MKI67 and neoplasm: It is worth noting that pathological classifications of panNENs have changed multiple times over the past 24 years, with panNENs currently classified as well-differentiated grade 1 (Ki-67 <3%), well-differentiated grade 2 (Ki-67 3–20%), well-differentiated grade 3 (Ki-67 >20%) or neuroendocrine carcinomas (poorly differentiated tumor with Ki-67 >20%), as reviewed in detail elsewhere (Rindi et al. 2022, Helderman et al. 2024).