Non-cirrhotic portal fibrosis (NCPF), the equivalent of idiopathic portal hypertension in Japan and hepato portal sclerosis in the United States of America , is a common cause of portal hypertension (PHT) in adult population of India accounting for 15 to 30% of cases, 1-3 .

In children the incidence varies in different studies 4, 5, 6 . However in Eastern India it is an important cause of PHT in children. The etiology of NCPF is poorly defined. A number of hypotheses have been proposed.

Infective Hypothesis: Clustering of cases mainly in the lower socio economic class suggests, abdominal infection at birth or in early childhood my play an important role… Umbilical sepsis, bacterial infections and diarrheal episodes in infancy and in infancy and in early childhood have been alleged to lead to portal pyemia, pylephlebities, resulting in thrombosis, sclerosis and obstruction of 3 rd and 4 th order intrahepatic portal vein radicles.

Idiopathic portal hypertension like changes in the liver and the development of PHT has been reported after injecting dead non-pathogenic colonic bacilli into the portal vein of rabbits and dogs 8-9 . In another model of indwelling cannulation of gastrosplenic vein, repeated injections of Escherichia coli resulted in development of splenomegaly and an increase in portal pressure at 3 months 10 .

Exposure to trace elements and chemicals: Prolonged ingestion of arsenic has been incriminated in the causation of NCPF 11 . Liver histopathology in patients with chronic arsenic ingestion reveals peri portal fibrosis incomplete septal cirrhosis with or without revascularization within the expanded portal zones suggestive of NCPF. In a Belgian study, a previous intake of arsenic as Fowler's solution for treatment of psoriasis was reported in eight of 47 NCPF patients 12 . Interestingly these patients had florid skin stigmata of arsenicosis, something not commonly experienced by us. <

A histological picture resembling NCPF has been observed following chronic exposure to vinyl chloride monomers, copper sulfate (vineyard sprayers) protracted treatment with methotrexate, hypervitaminosis A and in renal allograft recipients receiving treatment with 6 mercaptopurine and corticosteroids.

Immunologic and Immunogenetic hypothesis: All immunological basis for NCPF is currently under active investigation. Preliminary studies slowed severe granulocytopenia in NCPF 12, 13 . There is also reduction in the suppressor/cytotoxic T lymphocytes (T8) in NCPF patients and a decreased T4/T8 lymphocyte ratio 14 . A reduction of cell mediated immune status and a poor autologous mixed lymphocyte reaction (MLR) has also been documented 15 .

In a recent study, injection of splenic extract in presensitzed rabbits resulted in the development of an NCPF like picture, with splenomegaly and an increase in portal pressure with negligible parenchymal injury 10 .

In Japan , IPH if frequently associated with autoimmune disorders such as systemic lupus erythromatosus, progressive systemic sclerosis (PSS), thyroiditis and mixed connective tissue disease (MCTD) 15 . Nearly two-thirds of Japanese female patients with IPH test positive for anti-ds DNA antibody and one-quarter test positive for antinuclear antibody 16 . Such high prevalence of associated autoimmune conditions has not been the experience in the Indian Sub-continent.

No definite genetic predisposition to NCPF has been reported. However familial occurrence of NCPF is known. A high frequency of HLA-DR3 has been found in NCPF cases.

Based on clinical observations and available information it is proposed that NCPF and extra hepatic portal venous obstruction (EHPVO), both the venous inflow tract diseases could develop in a genetically predisposed individual when infection or a prothrombotic event could precipitate thrombosis in the portal vein or its radicals. If it is a major thrombosis event occurring at an early age in life, the main portal vein become occluded, leading to the development of EHPVO. However in the event of repeated microthrombotic events the small or medium branches of the portal veins are affected leading to the development of NCPF.

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