Etiology and diagnostic criteria
The disease is part of the group of autoimmune liver disorders, which also includes primary biliary cholangitis and primary sclerosing cholangitis. The exact etiology of the process has not yet been established. Genetic predisposition plays an important role: the HLA-B8 antigen is detected in more than half of the patients.
The diagnosis is based on serological and immunological data. A prerequisite is a negative result for viral hepatitis markers. Elevated levels of class G immunoglobulins (IgG) and circulation of various autoantibodies are detected in the patients' blood:
- Antinuclear antibodies (ANA).
- Antibodies to liver-kidney microsomal antigen (LKM).
- Antibodies to liver-specific protein (LSP).
- Smooth muscle antibodies (SMA).
Depending on the detected set of autoantibodies, 3 types of the disease are distinguished, although their histological picture is absolutely identical.
Clinical presentation and course
The pathology is characterized by continuous progression from the appearance of the first symptoms to a fatal outcome (if the patient receives no treatment).
Only in 10% of cases does the manifestation occur as acute hepatitis. In the vast majority of patients, the onset is insidious and gradual. Due to this hidden course, 10–20% of patients already have signs of decompensated liver cirrhosis at the time of diagnosis.
During exacerbations, the clinical presentation becomes pronounced. Patients complain of anorexia, abdominal pain, and fever. Objectively determined:
- Jaundice.
- Hemorrhagic syndrome.
- Hepatomegaly (enlargement of the liver).
- Splenomegaly (enlargement of the spleen, not always present).
Pathological anatomy (Morphology)
The histological picture corresponds to severe chronic hepatitis. The changes affect all structural elements of the liver tissue.
Hepatocyte changes Liver cells are characterized by marked polymorphism. Severe degeneration develops—hydropic and ballooning. Signs of regeneration are noticeable, manifested by the appearance of hepatocytes with two or more nuclei. In the first zone of the hepatic acinus, cells form specific structures—"rosettes".
Parenchymal necrosis The picture is characterized by frequent focal (spotty) necrosis, as well as periportal (piecemeal) necrosis.
Inflammatory infiltrate and stroma A lymphomacrophage infiltrate accumulates in the portal tracts. Its key feature is an admixture of a large number of plasma cells. Lymphoid follicles and macrophage granulomas may also form here. Fibroblast proliferation and sclerosis are observed in the stroma. In some cases, cholestasis and bile duct proliferation are noted.
Interface activity (Interface hepatitis) The inflammatory infiltrate is not limited to the portal tracts: it breaches the limiting plate, destroying it, and spreads into the first zone of the acinus.
Outcome and prognosis
Autoimmune hepatitis is characterized by high aggressiveness. The active course of the inflammatory process inevitably leads to the development of micronodular liver cirrhosis.
It is important to note that the frequency of transformation into cirrhosis in this pathology is significantly higher, and the overall prognosis for the patient is much more serious compared to chronic viral hepatitis.
Briefly: answers to topical questions
What types is autoimmune hepatitis classified into depending on the autoantibody profile?
Autoimmune hepatitis is classified into 3 types depending on the set of detected autoantibodies. Serological testing may reveal a wide spectrum of autoantibodies:
- Antinuclear antibodies (ANA).
- Liver-kidney microsomal antibodies (LKM).
- Liver-specific protein antibodies (LSP).
- Smooth muscle antibodies (SMA).
The morphological picture in all three types is similar.
What genetic markers (histocompatibility antigens) are associated with the development of autoimmune hepatitis?
The genetic marker HLA-B8 is associated with the development of autoimmune hepatitis. It is detected in more than 50% of patients. The disease has an unknown etiology. The risk group predominantly includes young women, who account for about 70% of patients.
What extrahepatic autoimmune diseases frequently accompany autoimmune hepatitis?
The following conditions may be combined with autoimmune hepatitis and autoimmune liver diseases or manifest extrahepatically:
- Autoimmune thyroiditis.
- Inflammatory bowel diseases, including ulcerative colitis.
- Sjögren's syndrome.
- Celiac disease.
- Hemolytic anemia.
- Idiopathic thrombocytopenic purpura.
- Glomerulonephritis.
- Vitiligo.
- Articular syndrome / arthralgias.
In an acute onset of autoimmune hepatitis in adults, systemic manifestations with fever and prominent extrahepatic autoimmune features may predominate.
The morphological picture of autoimmune hepatitis is easy to remember using the "P" rule: Plasma cells in the infiltrate, Piece-meal hepatitis (destruction of the plate), Periportal necrosis, Polymorphism of hepatocytes.
Class and exam questions
How does the inflammatory infiltrate in autoimmune hepatitis differ from that in viral hepatitis?
The main distinguishing feature is the presence of a large number of plasma cells in the lymphomacrophage infiltrate.
What is interface hepatitis?
This is a process in which the inflammatory infiltrate extends beyond the portal tracts into the first zone of the acinus, destroying the limiting plate of hepatocytes.
What hepatocyte changes are characteristic of this disease?
Marked cellular polymorphism, hydropic and ballooning degeneration, as well as the formation of "rosettes" and the appearance of multinucleated regenerating cells are observed.
What is the typical outcome of the disease?
The disease is characterized by an aggressive course and often leads to the development of micronodular liver cirrhosis. The prognosis is more serious than in viral hepatitis.
What else to study on this topic
- Primary biliary cholangitis (PBC)
- Primary sclerosing cholangitis
- Classification of autoimmune hepatitis (types 1, 2, and 3)
- Morphogenesis of micronodular liver cirrhosis
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