HISTOPATHOLOGY OF THE LIVER IN NONCIRRHOTIC PORTAL-HYPERTENSION OF UNKNOWN ETIOLOGY

Non-cirrhotic, long-standing portal hypertension of unknown aetiology is being re-evaluated histopathologically and clinically, In this stud y, we examined 107 livers with this condition (92 wedge biopsy and 15 autopsy specimens) from five institutions in Japan, These cases were h istologically categorized into four groups: idiopathic portal hyperten sion (66 cases), nodular regenerative hyperplasia (14 cases), partial nodular transformation (two cases), and incomplete septal cirrhosis (2 5 cases), These four groups shared several histological features: dens e portal fibrosis with portal venous obliteration and intralobular sle nder fibrosis. In addition, the histopathological features characteris tic of one group were also found to a mild degree in other groups. The histopathological lesions preceding portal venous obliteration remain speculative. However, the portal venous obliteration may be responsib le for the occurrence of sustained portal hypertension and several of the pathological changes in these livers, It seems likely that idiopat hic portal hypertension, nodular regenerative hyperplasia, partial nod ular transformation and incomplete septal cirrhosis comprise a family of non-cirrhotic, long-standing portal hypertension in Japan, and the histological differences between them may reflect chronological progre ssion of a single disease.