Table IV.

NASH Clinical Research Network (CRN) scoring system for nonalcoholic fatty liver disease (from Kleiner et al., 2005) ¹⁹.

Steatosis grade	Lobular Inflammation	Hepatocellular ballooning
0: < 5%	0: None	0: None
1: 5-33%	1: < 2 foci/20x field	1: Mild, few
2: 34-66%	2-4 foci/20x field	2: Moderate-marked, many
3: > 66%	3: > 4 foci/20x field
NAFLD activity score (NAS): 0-8
Fibrosis (evaluated with Masson trichrome stain)
0	None
1a	Mild zone 3 sinusoidal fibrosis (trichrome stain to be identified)
1b	Moderate zone 3 sinusoidal fibrosis (could be detected on H&E examination)
1c	Portal fibrosis only
2	Zone 3 sinusoidal fibrosis and periportal fibrosis
3	Bridging fibrosis
4	Cirrhosis

NASH: nonalcoholic steatohepatitis; NAFLD, nonalcoholic fatty liver disease.