1. بسم الله الرحمن الرحيم Noushin Afshar Moghaddam, M.D
Associate Professor of Medicine
Pathology Department
Isfahan University of Medical Sciences

2. Fatty liver

3. Steatosis
Steatosis (fatty liver, fatty change) corresponds to accumulation of triglycerides in the cytoplasm of hepatocytes. It is a frequent finding and represents a manifestation of reversible cell injury

4. Fatty Liver Any amount of fat in liver histology
Mirovesicular or macrovesicular
With or without inflammation
With or without fibrosis
Associated with other disease or not
Alcohol related or not
Alcoholic fatty liver / Non alcoholic fatty liver

5. Steatosis is a nonspecific lesion induced by a variety of causes.
The degree of lipid accumulation is variable, ranging from occasional fat droplets to diffuse deposition involving most parenchymal cells.
Minor amounts of steatosis are of uncertain significance, and occur more frequently in elderly people, possibly as part of the aging process.
More extensive steatosis is seen in a variety of primary hepatic diseases and ,in several systemic conditions.

6. Histologic preparation
Histologically, in routinely fixed tissue, steatosis is represented by cytoplasmic vacuoles as the lipid is dissolved during processing. Very small droplet steatosis may be difficult to recognize.
Lipid can be demonstrated in frozen sections using oil red 0, or Sudan black, or in tissue that has been postfixed in osmium tetroxide.

7. Patterns and distribution
Macrovesicular and microvesicular steatosis.
Both may occur together to some extent in the same biopsy specimen, suggesting that large droplets form through coalescence of small lipid vacuoles.

9. Normal liver 3 2 1

10. Normal liver

11. Normal liver

13. Acute fatty liver of pregnancy
Acute fatty liver of pregnancy. Detail of lobular parenchyma characterized by microvesicular steatosis and a small number of lymphocytes. (H&E)

14. Macrovesicular steatosis (large droplet fatty change)
It is the most common pattern.
Uncomplicated macrovesicular steatosis used to be regarded as a benign and potentially fully reversible lesion, but this notion has been challenged
Its zonal distribution is variable.
It is most often centrolobular, :alcoholic liver disease, obesity, and diabetes.
In more severe degrees, the steatosis may become panlobular.
Steatosis in periportal zones is more commonly seen in cachexia and protein-energy malnutrition (kwashiorkor), in acquired immune deficiency syndrome (AIDS), after total parenteral nutrition, with phosphorus poisoning, and in steroid therapy.

15. There are exceptions to the rule,however, and it is not possible to define the etiology solely on the pattern of lipid distribution in the individual case.
Identification of the cause requires close clinicopathologic correlation.

16. What’s the pathologist role?
The pathologist should provide information on severity by indicating the approximate amount of parenchyma involved (mild: less than one third; moderate: one third to two thirds; severe: more than two thirds).
Further useful information for the clinician is the finding of a mixed pattern of macro- and microvesicular steatosis because this may be of prognostic importance in relation to alcoholic liver disease.

17. Pathogenesis The pathogenesis of steatosis is complex.
Alterations at many points of the complicated pathway of lipid metabolism can lead to accumulation of neutral fat within hepatocytes.

18. Microvesicular steatosis (small droplet fatty change)
It is often more difficult to recognize, and its demonstration may require histochemistry.
It is generally a serious lesion associated with impairment of β-oxidation of lipids and frequently accompanied by disturbed liver function and coma.

19. Microvesicular steatosis (small droplet fatty change)
The causes are multiple.
Acute fatty liver of pregnancy
Reye's syndrome
Salicylates
Sodium valproate
Intravenous high dose tetracycline
Ethanol (in a small proportion of patients)
Inborn errors of mitochondrial fatty acid β-oxidation
Inherited urea cycle disorders

21. Classification of fatty liver disease
Alcoholic steatohepatitis or ASH
Non-alcoholic steatohepatitis or NASH

22. ASH vs. NASH No qualitative histologic differences.
When large groups of patients compared: alcoholics tend to develop more severe disease.
NASH usually associated with:
more:
fat
nuclear glycogen
less:
hepatocellular damage
inflammation
fibrosis
Mallory bodies

23. Non-Alcoholic Fatty Liver Disease (NAFLD)
Defined as:
Deposition of fat droplets in hepatocytes
AND the absence of significant alcohol intake
Generally defined as less than ( 140gr ) ethanol per week
NAFLD is a range of conditions from near normal liver to cirrhosis

24. Other Terms Simple non-alcoholic fatty liver disease (NAFLD)
Only deposition of fat in liver
No inflammation or fibrosis
Non-Alcoholic Steatohepatitis (NASH)
NAFLD with inflammation (lobular or portal), hepatocyte ballooning, or fibrosis
Absence of serologic evidence of infection with hepatitis B or hepatitis C, …
Exclude viral hepatitis,autoimmune and metabolic diseases

25. NAFLD—Spectrum of Disease
Steatosis
Steatohepatitis (NASH)
NASH with Fibrosis
Cirrhosis
NAFLD

26. NAFLD, simple steatosis
Fatty Liver
Only deposition of fat in liver
No inflammation
No fibrosis
Not believed to progress to cirrhosis
Up to 25 % of some populations!

27. NAFLD—Steatosis

28. Histological section of a murine liver showing severe steatosis
Histological section of a murine liver showing severe steatosis. The clear vacuoles would have contained lipid in the living cells, however the histological fixation caused it to be dissolved and hence only empty spaces remain

29. Deficiency of glucose-6-phosphatase results in accumulation of glycogen in hepatocytes. The liver is enlarged. The hepatocytes are swollen and a mosaic histological pattern with compression of the sinusoids is seen. Macro- and/or microvesicular steatosis can be present

30. Histological features considered necessary for the diagnosis of NASH
Steatosis of varying morphology:
Predominantly macro vesicular
Mixed lobular inflammation
Hepatocellular ballooning generally in zone 3
Other findings:
Perisunuzoidal fibrosis
Mallory’s bodies,fat cysts,glycogented nuclei
Acidophil bodies in kuppfer cells
Megamitochondria
Lipogranuloma

31. Alcoholic steatohepatitis with neutrophilic acute hepatitis

33. macrovesicular steatosis and ballooning

34. Ballooning degeneration

35. Mallory
Body

36. Mallory bodies:homogenous eosinophilic perinuclear
inclusions of variable size and shape. It composed of
hyperphosphorylated CK (7, 18, 19) together with
Ubiquitin heat shock protein.

38. NAFLD—NASH (without fibrosis)
Source: Ibdah 2003

39. glycogen "in" hepatocyte nuclei

40. Steatohepatitis:Some hepatocyte nuclei show glycogen vacuolation

42. Lipogranuloma.

43. Lipogranuloma.

44. periportal hepatic steatosis, as may be seen due to steroid
use. Trichrome stain

45. NAFLD—NASH (with fibrosis)
Source: Ibdah 2003

46. Micrograph of inflamed fatty liver (steatohepatitis)

47. Pericellular collagen and Mallory bodies (asterisks) in ballooned hepatocytes are stained blue. Chromotrope Aniline Blue stain.

48. (zone 3) sinusoidal fibrosis, typical of alcoholic

50. Steatohepatitis with cirrhosis.

51. Cirrhosis

52. NAFLD—Histological Spectrum
Cirrhosis
Time Progression
Fibrosis
Lobular Inflammation
Macrovesicular Steatosis

54. Grading and staging the histopathologic
Lesions of NASH

55. Grade 1(Mild)
Steatosis:predominantly macrovesicular,involves ‹33% up to 66% of the lobules
Ballooning: occasionally observed in zone 3
Lobular inflammation:scattered and mild acute (PMNs) inflammation and occasional chronic inflammation (mononuclear cells)
Portal inflammation:none or mild

56. Grade 2 (Moderate)
Steatosis: any degree and usually mixed macrovesicular, and microvesicular
Ballooning: obvious and present in zone 3
Lobular inflammation: PMNs may be noted with ballooned hepatocytes and pericellular fibrosis; mild chronic inflammatory cells may be seen.
Portal inflammation: mild to moderate

57. Grade 3 (Severe)
Steatosis:>66%(panacinar);commonly mixed type
Ballooning: predominantly in zone 3;marked
Lobular inflammation: scattered acute and chronic inflammation;PMNs may appear concentrated in zone 3 areas of ballooning and perisinozoidal fibrosis.
Portal inflammation: mild to moderate

58. Staging Fibrosis in NASH

59. NASH staging
Stage 1:Zone 3 perivenular perisinozoidal/ pericellular fibrosis, focal or extensive
Stage 2:As above with focal or extensive periportal fibrosis
Stage 3:Bridging fibrosis,focal or extensive
Stage 4:Cirrhosis

60. NASH/causes jejunoileal bypass surgery, gastroplasty
rapid and profound weight loss in obese subjects
total parenteral nutrition
drugs' (amiodarone,perhexiline maleate, estrogens and estrogen receptor ligands, methotrexate)
occupational hepatotoxicity
disorders characterized by extreme insulin resistance
In most cases the etiopathogenesis of NASH appears multifactorial (obesity, type 2 diabetes,and hypertriglyceridemia)
the hepatic consequence of the metabolic syndrome or cardiovascular dysmetabolic syndrome or syndrome X

61. Risk Factors for NAFLD in Children
Presence of Insulin Resistance
Diabetes
Consumption of foods high in sugar and calories
Soft drinks /cola
Fast and junk food
High Fructose intake
Lack of exercise
Time spent on TV/video games

63. (related to obesity and insulin resistance)
Ludwig(et.al) proposed a subclassification to include etiopathogenesis:
Primary NASH
(related to obesity and insulin resistance)
Secondary NASH
(post bypass surgery, drugs, and toxins)

64. Pathogenesis

65. Multiple Hit Theory Normal Liver Fatty Liver Steatohepatitis Cirrhosis
Hit 1: ? Insulin resistance, endotoxins, …
 Fat accumulation
Fatty Liver
Hit 2: ? Oxidative stress, …
 Inflammation
Steatohepatitis
Hit 3: ? Oxidative stress, …
 Fibrosis
Cirrhosis
May loose fat

66. NASH, Diagnosis Most patients are asymptomatic.
Hepatomegaly is the most common physical finding.
ALT / AST > 1, usually not so high
Ultrasound will demonstrate a fatty or “bright liver.”
In CT, the liver is darker than the spleen
Liver biopsy is required

67. Summary
The prevalence of NASH (2-3%) is comparable to the prevalence of hepatitis B, and much larger than the prevalence of hepatitis C
Since hepatitis B is being vaccinated for, we will be seeing less of this disease in the future
But obesity is on the rise. (as is hepatitis C)
It can be concluded that in the near future, NASH and hepatitis C will be the major liver diseases we will be facing in Iran