Table 1.
World Health Organization Classification and grading criteria for neuroendocrine neoplasms of the gastrointestinal tract and hepatopancreatobiliary organs (7)
|
Terminology
|
Differentiation
|
Grade
|
Mitoses/2 mm2
|
Ki-67 index
|
| NEN grade 1 | Well differentiated | Low | < 2 | < 3% |
| NEN grade 2 | Intermediate | 2-20 | 3%-20% | |
| NEN grade 3 | High | > 20 | > 20% | |
| SCNEC | Poorly differentiated | High1 | > 20 | > 20% |
| LCNEC | > 20 | > 20% | ||
| MiNEN | Well or poorly differentiated | Variable | Variable | Variable |
1
Poorly differentiated neuroendocrine carcinomas are not formally graded, but are considered high-grade by definition.
LCNEC: Large cell neuroendocrine carcinoma; MiNEN: Mixed neuroendocrine non-neuroendocrine neoplasm; NEN: Neuroendocrine neoplasm; SCNEC: Small-cell neuroendocrine carcinoma.