Table 1.

Pathological classification of NAFLD for diagnosis and evaluation of disease severity

References	Type	Description	Diagnosis of NASH
Matteoni [15]	Diagnosis	Type 1 (steatosis) Type 2 (steatosis + lobular inflammation) Type 3 (steatosis + ballooning) Type 4 (steatosis + fibrosis or steatosis + MDB)	Type 3 and 4
Brunt [20]	Severity	Grade (activity) 1–3 Stage (fibrosis) 1–4a	Not for diagnosis
NAFLD activity score (NAS) [21]	Diagnosis	Steatosis 0–3 Inflammation 0–3 Ballooning 0–3	Total score is 5 (4) or higher than 5 (4)
Younossi [23]	Diagnosis	(1) Steatosis + centrilobular ballooning and/or MDB (2) Steatosis + centrilobular pericellular/perisinusoidal fibrosis or bridging fibrosis	(1) or (2)

MDB Mallory–Denk bodies

^a Stage 1 was particularly classified by Kleiner et al. as a part of NAS (delicate perisinusoidal fibrosis in the perivenular area as 1A, dense perisinusoidal fibrosis in the perivenular area as 1B and detection of portal fibrosis without perisinusoidal fibrosis was defined as 1C.)