Disturbances of Intrahepatic Venous and Arterial Microcirculation in Idiopathic Portal Hypertension
Yasunori Sato, Kenichi Harada, Motoko Sasaki, Yasuni Nakanuma. Kanazawa University Graduate School of Medicine, Kanazawa, Japan
Background: Idiopathic portal hypertension (IPH) is a condition of non-cirrhotic portal hypertension without a known cause of liver disease, and obliterative portal venopathy is regarded as the primary lesion for the development of IPH. The obliteration of portal venules results in disturbed intrahepatic microcirculation, where its histological characteristics have not been fully clarified.
Design: Paraffin-embedded tissue sections of the livers of IPH (n = 27) and normal/subnormal livers (n = 20) were used. For the sections, triple immunohistochemical staining of glutamine synthetase (GS), alpha-smooth muscle actin (SMA), and cytokeratin (CK)7 was performed. GS, alpha-SMA, and CK7 were used to identify hepatic venules, muscular arteries, and bile duct/ductular cells, respectively.
Results: In normal/subnormal livers, the expression of GS was confined to a few layers of hepatocytes surrounding the central veins and small hepatic veins, showing normal liver zonation. Dilated portal veins herniating into the surrounding parenchyma (paraportal shunt vessels) were observed in 18 cases (67%) of IPH, and among the 18 cases, hepatocytes around the dilated portal veins showed positive immunohistochemical staining of GS in 7 cases. Isolated arteries in the hepatic lobules were seen in 20 cases (74%) of IPH, and they were located around the central vein in 6 cases (22%), corresponding to centrizonal arteries. In 2 cases (7%) of IPH, the centrizonal arteries were accompanied by ductular reaction, and the histological appearance mimicked the anatomy of a portal area. Isolated arteries were also observed in 5 cases (25%) of normal/subnormal livers, although their number was small and none of them were located in the centrizonal area. Broad, anastomosing hepatocellular expression of GS, which was similar to that seen in focal nodular hyperplasia, was observed in 5 cases (19%) of IPH, while such staining areas were not seen in normal/subnormal livers.
Conclusions: Intrahepatic microcirculatory disturbances in IPH were associated with abnormalities in both venous and arterial vessels. Several cases of IPH were accompanied by hyperplastic response of hepatocytes, which might relate to abundant blood supply due to the abnormal arteries. The vascular lesions were heterogenous, and differed from case to case of IPH.
Wednesday, March 6, 2013 1:00 PM
Poster Session VI # 108, Wednesday Afternoon