Etiology and pathogenesis
The causes of the disease are not yet fully understood, but its non-infectious nature has been reliably proven. Genetic predisposition plays an important role: familial cases occur in 1–7% of situations, and patients often exhibit specific genotypes (HLA-DR3, DR4, or DR2). Congenital or acquired insufficiency of the immunosuppressive system contributes to the development of the disease.
The pathogenesis is based on autoimmune cellular reactions that resemble graft-versus-host disease in their character and morphology.
- Target of aggression: major histocompatibility complex (HLA) antigens located on the epithelium of intrahepatic bile ducts. Their abnormally high density makes the biliary epithelium vulnerable to immune attack.
- Immune imbalance: there is an increase in the concentration and activity of T-helper cells accompanied by a decrease in T-suppressor function. T-helper cells and B-lymphocytes accumulate in the portal tracts, maintaining chronic inflammation.
- Cross-reactions: the destruction of the ducts triggers autoimmune reactions against other tissues. This is why the pathology is frequently combined with Hashimoto's thyroiditis, scleroderma, rheumatoid arthritis, and systemic lupus erythematosus.
Clinical presentation and systemic manifestations
The disease develops gradually. In the early stages, the most characteristic sign is pruritus. Initially, it is intermittent, then becomes constant. Due to the absence of jaundice at disease onset, patients may undergo long and unsuccessful treatments by dermatologists.
Other early symptoms include:
- Dark brown skin pigmentation (beginning in the scapular region due to melanin deposition).
- Appearance of xanthelasma.
- Enlargement of the liver and spleen.
- Blood tests reveal elevated levels of gamma-glutamyl transferase, alkaline phosphatase, and specific antimitochondrial antibodies (AMA-M2).
In the manifest stage, jaundice, fever, and weight loss appear. The skin becomes coarse, and areas of depigmentation resembling vitiligo may develop. The liver is significantly enlarged, occupying both hypochondria.
The disease rarely occurs in isolation and is accompanied by numerous extrahepatic manifestations:
- Sjögren's syndrome: involvement of the salivary and lacrimal glands occurs in 70–100% of patients.
- Gastrointestinal and pancreatic involvement: duodenitis, papillitis, as well as secretory pancreatic insufficiency leading to steatorrhea.
- Kidney involvement: development of glomerulonephritis or tubulointerstitial nephritis.
- Bone changes: bone tissue resorption, systemic osteoporosis, and osteomalacia.
- Lung involvement: excessive connective tissue development (associated with $\alpha_1$-antitrypsin deficiency).
- Endocrine disorders: ovarian dysfunction in women (amenorrhea, dysmenorrhea).
Pathological Anatomy
Macroscopically, the liver is somewhat enlarged and acquires a greenish tint due to pronounced cholestasis. In late stages, its surface becomes finely granular. Lymph nodes in the hepatic hilum are usually enlarged.
The microscopic picture goes through four consecutive stages:
- Stage I: non-suppurative destructive cholangitis. Inflammation destroys the bile ducts, leading to ductopenia (a progressive decrease in their number).
- Stage II: compensatory proliferation of small bile ducts against the background of connective tissue proliferation around portal tracts (periportal sclerosis).
- Stage III: formation of septal fibrosis, which disrupts the normal lobular structure of the organ.
- Stage IV: formation of true liver cirrhosis.
Complications and prognosis
The disease progresses slowly—from the appearance of the first symptoms to severe disorders takes an average of 10–12 years. The main complications include liver failure, bone fractures due to osteoporosis, gallstone formation, and bleeding.
Men have an increased risk of developing cholangiocellular carcinoma. In addition, against the background of immunodeficiency (including due to immunosuppressive therapy), the likelihood of extrahepatic malignant tumors increases.
In the terminal stage, signs of liver failure increase, ascites appears (which is not typical for early stages), along with encephalopathy and hepatorenal syndrome. Death most often results from esophageal variceal bleeding, hepatic coma, or septicemia.
Briefly: answers to topical questions
Which cells form the inflammatory infiltrate in the portal tracts during the first stage of primary biliary cirrhosis?
In the first (ductal) stage of primary biliary cirrhosis, the inflammatory infiltrate in the portal tracts is formed predominantly by lymphocytes, plasma cells, and eosinophils. Additionally, T-helper cells and B-lymphocytes secreting immunoglobulins accumulate in the area of cholangiole proliferation. Granulomas may also form around damaged interlobular and septal bile ducts.
What are the morphological differences between primary and secondary biliary cirrhosis?
The main morphological differences lie in the nature of bile duct damage and specific parenchymal changes.
| Sign | Primary biliary cirrhosis | Secondary biliary cirrhosis |
|---|---|---|
| Duct involvement | Non-suppurative destructive cholangitis and cholangiolitis of small intrahepatic ducts | Dilatation and tortuosity of intrahepatic ducts, proliferation of their epithelium |
| Specific changes | Ductopenia; possible formation of granulomas around damaged ducts | Formation of «bile lakes», «foamy» appearance of hepatocytes |
| Necrosis | Not specified for primary biliary cirrhosis in the cited sources | Focal hepatocyte necrosis and extensive periportal necrosis |
The analogy with graft-versus-host disease helps to remember the essence of pathogenesis: the immune system attacks its own bile ducts due to the high density of histocompatibility antigens (HLA) on their epithelium.
Class and exam questions
Why do patients with primary biliary cirrhosis often consult a dermatologist first?
Due to severe pruritus (which worsens at night) and skin darkening. These symptoms appear in the early stages, long before the development of classic jaundice.
Which autoimmune diseases are frequently associated with this pathology?
Sjögren's syndrome is most common (in 70–100% of patients). Association with Hashimoto's thyroiditis, scleroderma, rheumatoid arthritis, and systemic lupus erythematosus is also characteristic.
What is ductopenia?
This is a pathological decrease in the number of intrahepatic bile ducts. In primary biliary cirrhosis, it occurs in the first stage due to their destructive inflammation.
What else to study on this topic
- Mechanisms of portal hypertension formation in biliary cirrhosis
- Differential diagnosis with primary sclerosing cholangitis
- The link between immunosuppressive therapy and the risk of extrahepatic tumors
- Pathogenesis of bone changes (osteoporosis and osteomalacia) in prolonged cholestasis
- Secondary biliary cirrhosis: differences in etiology and pathogenesis
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