Porto-sinusoidal vascular disorder

Porto-sinusoidal vascular disease, PSVD, Idiopathic non-cirrhotic portal hypertension, INCPH, Hepatoportal sclerosis, Obliterative portal venopathy, Noncirrhotic portal fibrosis

Porto-sinusoidal vascular disorder is a rare liver condition that causes increased pressure in the blood vessels of the liver without the presence of cirrhosis, often remaining undetected until serious complications arise.

Table of contents

• What is porto-sinusoidal vascular disorder
• Associated anatomy
• Who is affected
• Possible causes and associated conditions
• Symptoms and clinical presentation
• Major complications
• Diagnosis
• Treatment and management
• Outlook and prognosis

What is porto-sinusoidal vascular disorder

Porto-sinusoidal vascular disorder (PSVD) is defined as a vascular liver disease characterized by the absence of cirrhosis (severe scarring of the liver) and the presence of specific changes in the liver’s blood vessels, with or without the presence of portal hypertension (increased blood pressure in the portal vein system)^[1]. The disorder affects the small blood vessels within the liver, particularly those connected to the portal veins (blood vessels that carry blood from the digestive organs to the liver) and sinusoids (tiny blood vessels inside the liver)^[2].

This condition is often under-recognized because of insufficient disease awareness among physicians^[2]. The term “porto-sinusoidal vascular disorder” is relatively new, proposed to replace older terminology such as “idiopathic non-cirrhotic portal hypertension” (INCPH). The new name better encompasses all aspects of this rare disorder, including patients in early stages who may not yet have portal hypertension, those who develop blood clots in the portal vein, and those with other coexisting liver conditions^[7].

Associated anatomy

• Liver
• Portal vein
• Hepatic sinusoids
• Spleen

Who is affected

Porto-sinusoidal vascular disorder is a rare disease that primarily affects young people, with an average age of 40 years^[8]. The condition has an incidence rate of approximately 1.8 cases per 100,000 persons and primarily affects men^[8].

The prevalence of PSVD varies geographically and is more commonly reported in developing countries than in developed countries^[2]. This geographic variation may be related to differences in exposure to risk factors, access to diagnostic services, or disease awareness among healthcare providers.

Possible causes and associated conditions

The exact cause of porto-sinusoidal vascular disorder is not yet fully known^[3]. Many theories about the development of PSVD have been proposed, indicating limited understanding of the disease process. The theories suggest that several factors may contribute to the development of the condition, which can be classified into five categories: long-term exposure to toxins and drugs, immunological disorders, chronic infections, clotting issues, and hereditary disorders^[3].

Half of the patients with PSVD also have associated diseases that may contribute to the development of the condition^[1]. For example, patients with common variable immunodeficiency (CVID) associated with Evans syndrome (a combination of autoimmune hemolytic anemia and immune thrombocytopenia) may develop PSVD^[6].

Symptoms and clinical presentation

Patients with porto-sinusoidal vascular disorder usually remain without symptoms until complications of portal hypertension arise^[1]. This means that many people may have the condition for years without knowing it, making early detection challenging.

When symptoms do appear, they are typically related to portal hypertension and may include splenomegaly (enlarged spleen), which can lead to pancytopenia (low counts of all types of blood cells)^[3]. Some patients may also experience sudden onset of hematemesis (vomiting blood) and melena (black, tarry stools), which indicate bleeding from the digestive tract^[3].

Laboratory findings may show mildly elevated liver enzyme levels and moderately elevated alkaline phosphatase levels, though these findings can fluctuate over time^[6].

Major complications

Variceal bleeding and portal vein thrombosis are major complications associated with PSVD^[1]. Esophageal varices are enlarged veins in the esophagus (food pipe) that develop due to increased pressure in the portal vein system. These enlarged veins can rupture and cause life-threatening bleeding. Some patients may develop multiple cords of esophageal varices that require medical intervention^[3].

Portal vein thrombosis, or blood clots in the portal vein, frequently occurs during the disease course and can worsen portal hypertension^[7]. Other complications include ascites (fluid accumulation in the abdomen) and splenomegaly leading to pancytopenia^[3].

Diagnosis

Diagnosing porto-sinusoidal vascular disorder requires multiple tests and procedures. A liver biopsy is mandatory for the diagnosis of PSVD^[2]. Specific histologic signs (changes seen under the microscope) include obliterative portal venopathy, nodular regenerative hyperplasia, and incomplete septal fibrosis^[2].

On microscopic examination, the liver architecture may be mildly disrupted with an irregular distribution of portal tracts and a vague nodular appearance. The portal veins may show thick walls, abnormal profiles, and narrowed or obliterated lumens^[6]. Special staining techniques, such as reticulin and trichrome staining, help highlight the characteristic features of the disease^[6].

Imaging findings suggestive of PSVD include the absence of liver surface nodularity, enlargement of segments IV and I of the liver, and normal or mildly elevated liver stiffness values in patients with signs of portal hypertension^[2]. Abdominal ultrasound, liver elastography (Fibroscan), and other imaging techniques may be used to evaluate the liver and detect signs of portal hypertension^[6].

A comprehensive workup typically includes blood tests to rule out other causes of liver disease, including tests for viral hepatitis, autoimmune antibodies, and other markers of liver function^[6]. Endoscopic evaluation may be performed to check for esophageal varices^[3].

Treatment and management

The treatment of porto-sinusoidal vascular disorder is focused on managing complications of portal hypertension, mainly through primary prevention of variceal bleeding and treatment of portal vein thrombosis^[1]. The treatment approach adopts the same strategy as that used for patients with cirrhosis^[2].

Management strategies include the use of non-cardio-selective beta blockers (medications that reduce blood pressure in the portal vein), endoscopic ligations (banding procedures to prevent bleeding from esophageal varices), and diuretics (medications that help remove excess fluid)^[1]. For patients presenting with acute variceal bleeding, band ligation, proton pump inhibitors, and blood transfusion may be required^[3].

In complicated or refractory forms of portal hypertension in PSVD, transjugular intrahepatic portosystemic shunt (TIPS) may be considered. This is a procedure that creates a new pathway for blood flow through the liver to reduce portal pressure. However, experience with TIPS in PSVD is limited and more research is needed to determine the right time and indication for its use^[11].

Currently, there is insufficient evidence to support the use of anticoagulants (blood thinners) for prevention of blood clots in these patients^[1]. At present, there is no treatment available to change the natural course of the disease or biomarkers that can predict patient outcomes^[8].

Outlook and prognosis

The long-term prognosis of PSVD is generally better than that of cirrhosis^[2]. The 10-year overall survival rate without the need for liver transplantation ranges from 40% to 82%, with a liver transplantation rate of 5% at five years^[8].

The prognosis is associated with several factors including age, specific signs of portal hypertension such as ascites, and underlying conditions^[2]. Despite receiving symptomatic treatment, some patients may continue to have pancytopenia due to splenomegaly and require close monitoring and follow-up^[3].

The lack of adequate preclinical models and the limited understanding of the disease’s underlying mechanisms make it hard to develop new therapies^[8]. Despite the increase in recognition of PSVD, further research is needed to enable early disease diagnosis, establish optimal screening methods, and develop strategies to slow down disease progression^[1].