Table 2 Classification and grading criteria for NEN (2019) [8]
From: Primary grade 2 neuroendocrine tumor of the ileal mesentery: a case report
Terminology | Differentiation | Grade | Mitotic rate (mitoses/10 HPF) | Ki-67 index |
|---|---|---|---|---|
NET G1 | Well differentiated | Low | < 2 | < 3% |
NET G2 | Intermediate | 2–20 | 3–20% | |
NET G3 | High | > 20 | > 20% | |
NEC small-cell type (SCNEC) | Poorly differentiated | High | > 20 | > 20% |
NEC large-cell type (LCNEC) | > 20 | > 20% | ||
MiNEN | Well or poorly differentiated | Variable | Variable | Variable |