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September 2009 Case of the Month
Compiled by: Karen Leigh Matthews, MD
History: A 19-year-old female with a history of primary sclerosing cholangitis (PSC) since the age of 11. She also has inflammatory bowel disease, but it’s still unclear whether it is Crohn’s disease or ulcerative colitis.
Exam: Long- and short-axis fat- and water-weightedimages were obtained before and after contrast administration. Standard MRCP protocol was utilized.
Findings: Intra-(Figure 1) and extra-hepatic (Figure 2) multi-focal areas of irregular stricture that alternate with normal-caliber ducts, giving them a beaded appearance. The pancreatic duct has a normal appearance (Figure 3).
Images:
Figure 1
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Figure 2
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Diagnosis: Primary sclerosing cholangitis
Discussion:
The etiology of primary sclerosing cholangitis is unknown, but it is thought to be an autoimmune process. It is a chronic, fibrosing inflammatory disease of the bile ducts. This process leads to cholestasis, bile-duct obliteration, and biliary cirrhosis.
There is a strong association with inflammatory bowel disease, particularly ulcerative colitis. A weaker association has been made with Crohn’s disease. (1).
Diagnostic criteria for PSC include:
1. Typical cholangiographic abnormalities -- including multifocal, intra-hepatic bile duct strictures alternating with normal-caliber ducts, which sometimes give a beaded appearance.
2. Appropriate clinical, biochemical, and hepatic histologic findings -- levels of serum bilirubin and alkaline phosphatase are increased in most patients, with a mean increase in the alkaline phosphatase level to three times the upper limit of normal. Histologic examination shows nonspecific inflammatory fibrosis of the portal triads and a lack of bile ducts.
3.Exclusion of secondary causes of sclerosing cholangitis -- for example, cholangitis related to AIDS. (2)
This disease is well-known in children, even though it more commonly occurs in adults. (4)
ERCP had long been the gold standard for diagnosis. However, in the last decade, MRCP has become used more often, particularly in following known disease. There are risks with ERCP, such as pancreatitis, bleeding, and sepsis, which are avoided with MRCP. A disadvantage to MRCP, however, is the fact that it lacks the interventional capabilities of ERCP, such as, biopsy, stent placement, or mechanical dilation of obstructing strictures.
Since MRCP evaluates only the duct lumen, T1, T2, and CE-MR are used to evaluate the duct wall and surrounding parenchyma. The extra-hepatic ducts will often show wall thickening greater than 2mm and wall enhancement greater than that of muscle or pancreas.
Cholangiocarcinoma is an uncommon lesion, but occurs in up to 15% of patients with PSC. An additional limitation of ERCP is insensitivity of demonstrating the extra-ductal extent of tumor. MR imaging can be more sensitive for finding these lesions. The success of endoscopic brush cytologic biopsy is variable. Therefore, it is impossible to exclude cholangiocarcinoma on the basis of a negative brush biopsy result.
MR Features of PSC:
1.Dilatation of intra- and extra-hepatic ducts
2.Multifocal irregular strictures that alternate with normal ducts, giving a beaded appearance
3.Pruning of peripheral ducts
4. Isolated peripheral ducts which have no connection to the central ducts
5. Periportal and portocaval lymph nodes common and reactive (1)
Treatment: Usually palliative, with medical therapy and dilation of ductal strictures. The only curative therapy is liver transplantation. Bile ducts do not regenerate and the inflammation progresses to cirrhosis, portal hypertension, and liver failure. (1)
References:
1. Siegelman, E. Body MRI. Elsevier, 2005.
2. Vitellas KM, KeoganMT, Freed KS, et al.. “Radiologic Manifestations of Sclerosing Cholangitis with Emphasis on MR Cholangiopancreatography.” Radiographics 2000; 20:959-75.
3. Ernst, O, Asselah, T, Sergent, G, et al.“MR Cholangiography in Primary Sclerosing Cholangitis,” AJR 1998; 171:1027-1030.
4. Ferrara C, Valeri G, Salvolini L, Giovagnoni A. “Magnetic Resonance Cholangiopancreatography in Primary Sclerosing Cholangitis in Children.” Pediatr Radiol 2002; 32:413-417.
5.Heller, SL, Lee, VS. “MR Imaging of the Gallbladder and Biliary System” Magn Reson Imaging Clin N Am 13 (2005) 295-311. |
