Causes of Non-Cirrhotic Portal Fibrosis
Non-cirrhotic portal fibrosis (NCPF) is primarily caused by obliterative portovenopathy leading to portal hypertension, with key etiologies including exposure to volatile chemicals, vascular disorders, and certain systemic conditions. 1, 2
Toxic and Chemical Exposures
Volatile chemicals: Exposure to industrial chemicals including:
- Benzene
- Xylene
- Vinyl chloride monomer (VCM)
- Copper sulfate (in vineyard sprays)
- Nitrosamines (in rubber industry workers) 1
Mechanism: These toxicants can cause endothelial injury in sinusoids, leading to progressive periportal fibrosis without cirrhosis
Vascular Disorders
- Porto-sinusoidal vascular disease: Characterized by portal vein obliteration with progressive periportal fibrosis 1
- Sinusoidal obstruction syndrome (SOS): Results from endothelial injury in sinusoids, predominantly in centrolobular areas 1
- Obliterative venopathy: Sclerosis and obliteration of small-sized portal vein radicles 2
Systemic Diseases and Conditions
Immunological disorders:
- Systemic lupus erythematosus
- Rheumatoid arthritis
- Scleroderma 3
Hematological disorders:
- Myeloproliferative disorders
- Prothrombotic conditions
- Antiphospholipid syndrome 4
Infectious causes: Chronic or recurrent bacterial infections, especially in developing countries 5, 6
Diagnostic Features
Portal hypertension in NCPF is characterized by:
- Patent portal and hepatic veins
- Absence of cirrhosis on liver biopsy
- Preserved liver function
- Low liver stiffness measurement by transient elastography (<12 kPa) 4
Histopathological Findings
- Maintained lobular architecture
- Portal fibrosis of variable degree
- Sclerosis and obliteration of small portal vein radicles
- Subcapsular scarring with collapse of underlying parenchyma
- Absence of piecemeal or hepatocytic necrosis 2
Clinical Presentation
- Massive splenomegaly
- Anemia (often due to hypersplenism)
- Well-tolerated episodes of variceal bleeding
- Preserved liver function
- Rare occurrence of jaundice, ascites, or hepatic encephalopathy 2, 5
Special Considerations
- More common in developing countries, particularly India
- Typically affects young adults from lower socioeconomic backgrounds
- Has better prognosis compared to cirrhotic portal hypertension
- May develop spontaneous portosystemic shunts (splenorenal or umbilical) which can protect against variceal bleeding 2
Late Manifestations
- Some patients may progress to nodular transformation with abnormal liver function
- Features similar to incomplete septal cirrhosis may develop in advanced stages 2
NCPF remains a diagnosis of exclusion requiring the definite absence of liver cirrhosis and extrahepatic portal vein obstruction, with clinical evidence of portal hypertension.