Sclerosing Cholangitis (PSC)

Primary sclerosing cholangitis (PSC) PSC is a chronic hepatobiliary disease in which the walls of the bile ducts become inflamed, causing narrowing. It occurs predominantly in young men (with a 2:1 male to female ratio) and is characterized by multiple biliary strictures and bead-like dilatations of the ducts. The aetiology of PSC remains unclear but is associated with inflammatory bowel disorders or may be idiopathic. Clinical features include jaundice, itching and fatigue. Some 25% of patients also have gallstones, which complicates the diagnosis. Approximately 70% of patients affected also have ulcerative colitis. It is progressive gradual fibrosis which eventually obliterates the biliary tree. Untreated, this eventually leads to hepatic failure. PSC has a strong association with cholangiocarcinoma, and it is this, rather than hepatic failure, which may lead to death. In the absence of malignancy, however, hepatic transplant has a 70–90% 5-year survival rate.

Ultrasound images appearances

The ultrasound appearances in PSC may be normal or may demonstrate a coarse, hyperechoic texture throughout the liver. Ductal strictures may cause downstream dilatation in some segments (Fig. A) and in some cases there is marked biliary dilatation, but in the majority of patients the biliary ducts are prevented from dilatation by the surrounding fibrosis and so appear unremarkable on ultrasound. MRCP is superior at demonstrating intrahepatic ductal strictures. Mural thickening, particularly in the CBD, may be demonstrated with careful, highresolution scanning31 (Fig. B).
Ultrasound also demonstrates the effects of portal hypertension in advanced disease. The gallbladder may also have a thickened wall and can be dilated. Due to the association between PSC and cholangiocarcinoma, which may be multifocal, a careful search must be made for mass lesions. Because the ultrasound appearances may be those of a coarse, nodular liver texture, it is difficult to identify small cholangiocarcinomas and colour or power Doppler may be an advantage here (Fig.C). This diagnosis is an important one, because the patient’s prognosis and management are affected by the presence of cholangiocarcinomata. If no masses are identified, the prognosis is good and includes the endoscopic removal of stones to relieve symptoms, endoscopic stenting of main duct strictures to relieve jaundice and subsequent liver transplant to pre-empt the formation of carcinoma. However, if carcinoma is already present, 5-year survival falls to 10%.

fig. A

Localized biliary dilatation due to a
ductal stricture in a patient with primary sclerosing
cholangitis (PSC)

FIG.B

Coarse-textured liver with a dilated
CBD in PSC. A small choledochal cyst is present just
anterior to the lower CBD.

FIG.C (A & B)

PSC. (A) A tiny, suspicious, hyperechoic focal lesion (arrow) demonstrates increased flow on colour
Doppler. (B) The spectral waveform confirms vigorous arterial flow in this small cholangiocarcinoma