5. Histological grade criteria of colorectal cancer (based on version WHO 2010).
Criterion | Differentiation category | Numerical grade* | Descriptive grade |
*, undifferentiated carcinoma (grade 4) is reserved for carcinomas with no gland formation, mucin production, neuroendocrine, squamous or sarcomatoid differentiation; WHO, World Health Organization; MSI-H, high-level microsatellite instability. | |||
>95% with gland formation | Well differentiated | 1 | Low level |
50%−95% with gland formation | Moderately differentiated | 2 | Low level |
0−49% with gland formation | Poorly differentiated | 3 | High level |
MSI-H | Variable | Variable | Low level |