|
Histological Scoring System
for Nonalcoholic Fatty Liver Disease
(NAFLD)
Components of
NAFLD Activity Score (NAS) and
Fibrosis Staging
|
NAS
Components (see scoring
interpretation) |
|
Item |
Score |
Extent |
Definition and Comment |
|
Steatosis |
0 |
<5% |
Refers to
amount of surface area
involved by steatosis as
evaluated on low to medium
power examination; minimal
steatosis (<5%) receives a
score of 0 to avoid giving
excess weight to biopsies
with very little fatty
change |
|
1 |
5-33% |
|
|
2 |
>33-66% |
|
|
3 |
>66% |
|
|
Lobular
Inflammation |
0 |
No foci |
Acidophil
bodies are not included in
this assessment, nor is
portal inflammation |
|
1 |
<2 foci/200x |
|
|
2 |
2-4 foci/200x |
|
|
3 |
>4 foci/200x |
|
|
Hepatocyte Ballooning |
0 |
None |
|
|
1 |
Few
balloon cells |
The term
"few" means rare but
definite ballooned
hepatocytes as well as cases
that are diagnostically
borderline |
|
2 |
Many
cells/prominent ballooning |
Most
cases with prominent
ballooning also had
Mallory's hyalin, but
Mallory's hyaline is not
scored separately for the
NAS |
|
Fibrosis
Stage (Evaluated separately
from NAS) |
|
Fibrosis |
0 |
None |
|
|
|
1 |
Perisinusoidal or periportal |
|
|
|
1A |
Mild,
zone 3, perisinusoidal |
"delicate"
fibrosis |
|
|
1B |
Moderate,
zone 3, perisinusoidal |
"dense"
fibrosis |
|
|
1C |
Portal/periportal |
This
category is included to
accommodate cases with
portal and/or peri portal
fibrosis without
accompanying pericellular/perisinusoidal
fibrosis |
|
|
2 |
Perisinusoidal and portal/periportal |
|
|
|
3 |
Bridging
fibrosis |
|
|
|
4 |
Cirrhosis |
|
Total NAS
score represents the sum of
scores for steatosis, lobular
inflammation, and ballooning,
and ranges from 0-8. Diagnosis
of NASH (or, alternatively,
fatty liver not diagnostic of
NASH) should be made first, then
NAS is used to grade activity.
In the reference study, NAS
scores of 0-2 occurred in cases
largely considered not
diagnostic of NASH, scores of
3-4 were evenly divided among
those considered not diagnostic,
borderline, or positive for
NASH. Scores of 5-8 occurred in
cases that were largely
considered diagnostic of NASH.
Related Criteria
Diagnostic Criteria for Zollinger-Ellison Syndrome (ZES)
Diagnostic Criteria for
Autoimmune Hepatitis (AIH)
Diagnostic Criteria for Wilson's disease
Severity Criteria for Acute
Pancreatitis
More...
References:
-
Kleiner DE, Brunt EM,
Van Natta M, Behling
C, Contos MJ, Cummings
OW, Ferrell LD, Liu YC,
Torbenson MS,
Unalp-Arida A, Yeh M,
McCullough AJ, Sanyal
AJ; Nonalcoholic
Steatohepatitis
Clinical Research
Network. Design and
validation of a
histological scoring
system for
nonalcoholic fatty
liver disease.
Hepatology. 2005
Jun;41(6):1313-21.
[Medline]
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