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Histologic Scoring and Grading System of Mendler et al for Non-Alcoholic Fatty Liver Disease (NAFLD)

Purpose: To evaluate the liver biopsy from a patient with nonalcoholic fatty liver disease using the histologic scoring scheme of Mendler et al.

Description

Mendler et al have proposed a histologic scoring and grading system for liver biopsies taken from patients with non-alcoholic fatty liver disease (NAFLD). This can be used for initial diagnosis and for monitoring the patient over time. The authors are from the University of Southern California in Los Angeles.


Graded histologic features:

(1) portal fibrosis

(2) perisinusoidal fibrosis

(3) lobular inflammation and necrosis (LIN)

(4) Mallory bodies

(5) ballooning of hepatocytes

(6) fatty change (steatosis)

 

Parameter

Finding

Points

portal fibrosis

none

0

 

fibrosis in some portal triads, with or without short fibrous septae

1

 

fibrosis in most portal triads, with or without short fibrous septae

2

 

fibrosis in most portal triads, with occasional portal-to-portal and/or portal-to-central vein bridges

3

 

fibrosis in most portal triads, with marked portal-to-portal and/or portal-to-central vein bridges

4

 

marked portal-to-portal and/or portal-to-central vein bridges with occasional regenerative nodules

5

 

cirrhosis

6

perisinusoidal fibrosis

none

0

 

perivenular and/or periportal focal in some lobules

1

 

perivenular and/or periportal focal in most lobules

2

 

diffuse interstitial fibrosis in some or most lobules (AND focal perivenular and/or periportal in most or all lobules)

3

lobular inflammation and necrosis

none

0

 

focal in some lobules

1

 

focal in most lobules

2

 

diffuse in some or most lobules (AND focal in most or all lobules)

3

Mallory bodies

none

0

 

focal in some lobules

1

 

focal in most lobules

2

 

diffuse in some or most lobules (AND focal in most or all lobules)

3

hepatocyte ballooning

none

0

 

focal in some lobules

1

 

focal in most lobules

2

 

diffuse in some or most lobules (AND focal in most or all lobules)

3

fatty change

1 - 4% of hepatocytes

1

 

5 - 33%

2

 

34 - 66%

3

 

> 66%

4

 

where:

• The grading of portal fibrosis is based on the scheme for chronic hepatitis of Ishak et al. (J Hepatology. 1995; 22: 696-699). Grade 3 was modified to include portal-to-central bridges.

• Steatosis does not have a grade 0 (no fatty change) since some fatty change must be present by definition. The amount of fat per involved hepatocyte is not scored.

 

activity score =

= (points for perisinusoidal fibrosis) + (points for lobular inflammation and necrosis) + (points for Mallory bodies) + (points for ballooning hepatocytes)

 

Interpretation:

• mininum activity score: 0

• maximum activity score: 12

• The portal fibrosis and activity scores can be used to grade the severity of the hepatic involvement.

 

Features

Grade

portal fibrosis 0 - 2 and activity score 0 - 4

1

portal fibrosis 3 OR activity score 5 - 7

2

portal fibrosis 4 - 6 OR activity score 8 - 12

3

after Figure 4


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Specialty

Objective

ICD-10