بسم الله الرحمن الرحيم

1. بسم الله الرحمن الرحيم NoushinAfsharMoghaddam, 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. 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 NAFLD Steatosis Steatohepatitis (NASH) NASH with Fibrosis Cirrhosis

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. 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,fatcysts,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:homogenouseosinophilicperinuclear 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. periportalhepatic 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.