| Grade | ENETS, 2010 | WHO, 2010 |
| Low grade | Grade 1 NET (G1) | G1 Neuroendocrine neoplasm |
| Intermediate grade | Grade 2 NET (G2) | G2 Neuroendocrine neoplasm |
| High grade | Grade 3 neuroendocrine carcinoma (G3), small-cell carcinoma Grade 3 neuroendocrine carcinoma (G3), neuroendocrine large-cell carcinoma | Grade 3 neuroendocrine carcinoma, small-cell carcinoma Grade 3 neuroendocrine carcinoma, neuroendocrine large-cell carcinoma |