Pathologically, Distinguishing G3 pNETs from pNECs is difficult due to shared proliferation indices (Ki67 > 20%), leading to diagnostic ambiguity in some cases despite immunohistochemistry and molecular testing (22), and more aggressive histopathological features (23), but biopsies can be unreliable since they sample only a small part of the tumor that can be unrepresentative of the whole tumor, and waiting for surgery and the pathological examination of the specimen can lead to missed therapeutic opportunities (22). This evidence concerns the gene MKI67 and neoplasm.