Sinusoidal obstruction syndrome

Sinusoidal obstruction syndrome (SOS), also known as veno-occlusive disease (VOD), is a condition characterized by damage to the sinusoidal endothelial cells in the liver. This damage leads to the obstruction of the small veins in the liver, causing a range of symptoms and complications.

Pathophysiology

The primary mechanism of SOS involves injury to the endothelial cells lining the hepatic sinusoids. This injury can be caused by various factors, including chemotherapy, radiation therapy, and certain toxins. The damaged endothelial cells become swollen and detached, leading to the obstruction of the sinusoids and small hepatic veins. This obstruction results in impaired blood flow through the liver, causing increased pressure in the liver's blood vessels and subsequent liver dysfunction.

Causes

SOS is most commonly associated with high-dose chemotherapy and hematopoietic stem cell transplantation (HSCT). Other potential causes include exposure to certain toxins such as pyrrolizidine alkaloids found in some herbal remedies, and radiation therapy to the liver.

Symptoms

The symptoms of SOS can vary in severity and may include:

• Hepatomegaly (enlarged liver)
• Jaundice (yellowing of the skin and eyes)
• Ascites (accumulation of fluid in the abdomen)
• Weight gain due to fluid retention
• Right upper quadrant pain

Diagnosis

The diagnosis of SOS is based on clinical criteria, laboratory tests, and imaging studies. Key diagnostic criteria include:

• Rapid weight gain
• Painful hepatomegaly
• Elevated levels of bilirubin in the blood

Imaging studies such as ultrasound or CT scan may show signs of liver enlargement and ascites.

Treatment

The management of SOS involves supportive care and addressing the underlying cause. Treatment options may include:

• Diuretics to manage fluid retention
• Analgesics for pain relief
• Defibrotide, a medication that has been shown to improve outcomes in patients with severe SOS

Prognosis

The prognosis of SOS depends on the severity of the condition and the underlying cause. Mild cases may resolve with supportive care, while severe cases can lead to significant liver dysfunction and may be life-threatening.

Related Pages

• Liver
• Endothelial cells
• Chemotherapy
• Hematopoietic stem cell transplantation
• Jaundice
• Ascites