Subgrading of G2 Pancreatic Neuroendocrine Tumors Reveals Behaviorally Distinct Subsets

Subgrading G2 pancreatic neuroendocrine tumors into 2A (Ki67 3% to < 10%) and 2B (10% to ≤ 20%) identifies distinct subsets with different metastasis rates and aggressiveness. G2B cases show significantly higher rates of liver/distant metastasis, lymph node metastasis, and histopathologic signs of aggressiveness compared to G2A. G2B tumors behave similarly to G3, suggesting they may require more aggressive treatment strategies. This subcategorization should be considered in diagnostic guidelines to tailor management protocols accordingly, potentially necessitating closer follow-up for the higher-risk G2B group.