Table 1.
Definitions of the WHO 2017 and 2010 grading classification for p-NENs and distributions of patients in the present study according to these two criteria
| Definitions | Distributions | ||
|---|---|---|---|
| Classification | Mitotic rateA | Ki-67 proliferation index (%)B | Cases(%) |
| WHO 2017 grading criteria [7] | |||
| Well-differentiated p-NENs: | |||
| NET G1 | < 2 | < 3 | 150 (31.3%) |
| NET G2 | 2–20 | 3–20 | 158 (32.9%) |
| NET G3 | > 20 | > 20 | 64 (13.3%) |
| Poorly-differentiated p-NENs: | |||
| NEC G3 (small cell and large cell subtypes) | > 20 | > 20 | 108 (22.5%) |
| WHO 2010 grading criteria [8] | |||
| Well-differentiated endocrine tumor, G1: | |||
| NET G1 | < 2 | < 3 | 150 (31.3%) |
| Well-differentiated endocrine tumor, G2: | |||
| NET G2 | 2–20 | 3–20 | 158 (32.9%) |
| Poorly-differentiated neoplasm: neuroendocrine carcinoma, G3 (small cell and large cell type): | |||
| “NEC G3” | > 20 | > 20 | 172 (35.8%) |
A: The mitotic rate is based on the evaluation of mitoses in 50 high power fields in areas of higher density, and is expressed as mitoses per 10 high power fields
B: The Ki-67 proliferation index is based on the evaluation of ≥500 cell in areas of higher nuclear labeling (hot spot)
Abbreviation: WHO World Health Organization; p-NENs Pancreatic neuroendocrine neoplasms; NET Neuroendocrine tumors; NEC Neuroendocrine carcinoma; G Grading