Portal Venous Obstruction

 Portal vein thrombosis


image Reduced portal flow velocity (stasis)

image Vascular injury

image Tumor thrombosis

image Extrinsic compression by mass or fibrogenic lesions

image Congenital vascular anomalies


• Intrahepatic
image Propagation of large portal vein thrombosis or emboli

image Diseases that affect small portal veins

image Specific etiology may not be identifiable




Clinical Issues




• 5-10% in patients with portal hypertension in developed countries

• Sequelae depend on location, cause, time course, and extent of blockage


Microscopic




• Often inconsistent or irregularly distributed, may be missed in biopsy specimens
• Subtle alterations of portal venules

image Dilated portal venules

image Multiple collateral venules

image Herniation of portal venules into parenchyma

image Obliteration of portal venules, similar to hepatoportal sclerosis, may be seen

• Infarcts of Zahn
image Persistent occlusion can lead to atrophy of entire segments of liver

image True infarcts rarely develop

• Nodular regenerative hyperplasia may be seen

• Findings suggestive of underlying etiologies


Top Differential Diagnoses




• Hepatoportal sclerosis

• Normal liver

image
Portal Vein Thrombosis
Gross photograph of this liver explant shows a large portal vein thrombus image in the hilar region. Propagation into smaller intrahepatic portal veins image is also grossly noticed.


image
Dilated Portal Venule
This microphotograph shows a markedly dilated portal venule image in the setting of portal vein thrombosis. Note the presence of fibrin thrombus in the lumen.

image
Herniated Portal Venule
Typical changes in portal venous obstruction include dilated portal venules with “herniation” of the vessel into the surrounding parenchyma. Note the presence of a bile duct image in compressed portal stroma.

image
Collateral Venules
Multiple collateral venules image are present in this portal tract in a case of portal venous obstruction indicating elevated portal pressures.


TERMINOLOGY



Synonyms




• Idiopathic portal hypertension
image Many cases of idiopathic portal hypertension probably represent undetected portal vein thrombosis

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Apr 20, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Portal Venous Obstruction

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