—  SHORT COURSE   —

Disorders of the Intra- and Extrahepatic Bile Ducts

Case 2: Primary Sclerosing Cholangitis, Stage 4

Kay Washington, M.D., Ph.D.
Pathology, C-3321 MCN
Vanderbilt University Medical Center
Nashville, TN 37232-2561


Clinical History
A 37 year old woman presented with right upper quadrant abdominal pain. Serum bilirubin level was 1.4 mg/dL; ALT and AST were slightly above normal levels. A retrograde endoscopic cholangiogram showed an irregular common bile duct with stricture. Two years later the serum bilirubin level was 13.9 mg/dL. The patient underwent liver transplantation.

Morphologic Features
On gross examination, the liver was of normal size and was not shrunken, weighing 2700 grams. The cut surface was bile stained and the parenchyma was nodular and firm, with increased scarring in the hilar area. Microscopically, the most striking feature is the loss of interlobular bile ducts, which have been replaced by rounded, almost acellular fibrous scars. Smaller intact bile ducts show pronounced periductal fibrosis. Portal-portal bridging is present, and the resulting nodules have irregular outlines. Numerous canalicular bile plugs are seen, and hepatocytes adjacent to portal tracts and fibrous scars show changes of cholate stasis. A large bile duct contains inspissated bile. In some portal tracts, bile ductular proliferation is present, although it is not prominent in most areas. There is a moderate periportal lymphocytic inflammatory infiltrate. A small amount of Mallory's hyaline is present in zone 1, although it is inconspicuous.

Click on each slide thumbnail image for an enlarged view:

Slide 4
Primary Sclerosing Cholangitis
Concentric periductal "onion-skinning" fibrosis with atrophy and injury to bile duct epithelium is the classic lesion seen in primary sclerosing cholangitis, but this pattern of ductal injury is not seen in all cases and may be absent in needle biopsy specimens.
Slide 5
Sclerosing Cholangitis Associated with Primary Immunodeficiency
Sclerosing cholangitis-type changes may be seen in patients with immunodeficiencies, as in this case of common variable immunodeficiency. Such lesions are also seen in patients with AIDS. Various infectious agents such as Cryptosporidium, cytomegalovirus, and microsporidium have been implicated etiologic agents, although none was identified in this case.
Slide 6
Sclerosing Cholangitis Associated with Primary Immunodeficiency
The interlobular bile duct shows degenerative changes, such as pyknosis, and is surrounded by loose concentric fibrosis.


Diagnosis: Primary Sclerosing Cholangitis, Stage 4

Clinical Features
In contrast to primary biliary cirrhosis, primary sclerosing cholangitis is a disease of men, with a male predominance of 2:1. The median age of onset is low (30 years) but there is an extraordinarily wide age range of 1 to 90 years. PSC was previously thought to be rarer than PBC, but is probably about equal in prevalence. The prevalence of PSC in the USA is estimated as 2 to 7 cases/100,000 population ,1  but this is likely to be an underestimate.

The association of PSC with ulcerative colitis remains an enigma. Approximately 70% of patients with PSC have ulcerative colitis. Conversely, 3-7.5% of patients with ulcerative colitis have PSC. The ulcerative colitis typically involves a majority of the colon, but often has a relatively mild clinical course. Patients with PSC and UC may be at even higher risk for adenocarcinoma of the colon than the usual patient with UC ,2,3  and patients with PSC may be at higher risk for pancreatic carcinoma .2  Like PBC, PSC is considered to be a disease of autoimmunity, and a marked increase in prevalence of HLA antigens B8 and DR3 has been found in patients with PSC .4  The HLA-DR3, DQ2 heterozygous genotype may be associated with more rapid disease progression .5  The HLA B8, DR3 haplotype has been associated with a number of autoimmune diseases such as autoimmune hepatitis, thyroiditis, celiac disease, and myasthenia gravis.

The natural history of PSC is more variable than that of PBC. For the most part PSC is a progressive disease, with over 90% of patients with stage II (periportal disease) progressing over 5 years .6  Because of the presence of bile duct strictures and the formation of biliary stones and sludge, PSC is commonly complicated by bacterial cholangitis. The development of cholangiocarcinoma is a major complication, seen in up to 16% of PSC patients. Accurate diagnosis of cholangiocarcinoma remains a problem in many cases, as tumor may be indistinguishable from stricture on cholangiogram and accurate cytologic diagnosis from bile duct brushings may be exceedingly difficult. Elevated CA19-9 levels, if greatly elevated, may be of utility, although considerable overlap with PSC without cancer is seen .7 

Features of Primary Biliary Cirrhosis and
Primary Sclerosing Cholangitis
  Primary biliary cirrhosis Primary sclerosing cholangitis
Age Median age 50 years (30-70) Median age 30 years
Gender 90% female 70% male
Clinical Course Progressive Unpredictable but progressive
Associated conditions Sjogren's syndrome (70%)
Scleroderma (5%)
Rheumatoid arthritis
Thyroid disease (20%) 		Inflammatory bowel disease
Pancreatitis (up to 25%)
Idiopathic fibrosing diseases (retroperitoneal fibrosis)
Serology (1) 95% AMA +
20% ANA +
60% ANCA + 		0-5% AMA + (low titer)
6% ANA +
82% ANCA +
Radiology Normal Strictures and beading of large bile ducts; "pruning" of smaller ducts
Duct lesion Florid duct lesion; loss of small ducts Concentric periductal fibrosis; loss of small ducts


Diagnosis and Role of Liver Biopsy
Diagnosis of PSC is established on radiographic grounds, by the cholangiographic appearance of beading and irregularity of the biliary system and indeed cholangiography is the diagnostic gold standard for PSC. Although serum antineutrophilic antibodies (ANCA) are presentin 80% of PSC patients, this test is considered of limited use in diagnosis because of overlap with autoimmune hepatitis. Liver biopsy is undertaken to rule out other causes of liver disease and for staging purposes. Most hepatologists understand that liver biopsy alone is rarely diagnostic in this disease, as the disease process may be patchy in the liver and small intrahepatic bile ducts may not show diagnostic changes.

The diagnosis of small duct PSC is made in patients without large duct involvement who have inflammatory bowel disease and cholestatic liver disease with morphologic features of PSC on liver biopsy. This variant may represent an earlier stage of PSC and may be associated with a more benign long term prognosis .8 

Pathologic Features
A wide variety of morphologic changes which reflect the varying levels of duct involvement are seen in PSC. Unfortunately, the classic lesion of periductal concentric "onion-skinning" fibrosis is rarely seen in needle biopsy specimens. This pattern of fibrosis often has only a sparse inflammatory infiltrate. The bile duct epithelium is atrophic and epithelial cells are shrunken, with pyknotic nuclei. A rounded scar often marks the site of a destroyed bile duct. Alternatively the smaller interlobular bile ducts may vanish without a trace ,9  especially in pediatric cases, and residual scars are not identified. Interlobular bile ducts may be distorted in a subtle fashion, with only angulated profiles and irregular spacing of duct cell nuclei to indicate epithelial injury. The bile duct epithelium may be vacuolated and focally infiltrated by lymphocytes. The portal inflammatory infiltrate is usually sparse and primarily made up of mononuclear inflammatory cells, with scattered eosinophils. Early in the disease portal eosinophils may be unusually prominent. Portal granulomas are distinctly unusual although a granulomatous response to leakage of bile products does occur in 3 to 4% of biopsies .10  Lobular changes early in the disease are generally minor; late in the disease, changes of chronic cholestasis are common. The pattern of fibrosis is similar to that seen in primary biliary cirrhosis.

Changes of large duct obstruction are often superimposed on small duct changes of PSC. Bile ductular proliferation is common, and periductal edema and acute cholangitis may also be seen, especially in the setting of bacterial cholangitis. Canalicular bile plugs may be present.

The large bile ducts most commonly involved by PSC are of course not present in needle biopsy specimens. In the liver explant, larger intrahepatic bile ducts are often dilated and contain inspissated bile plugs and sludge. The walls of large bile ducts are fibrotic and contain chronic inflammatory cells. Reactive changes in entrapped peribiliary glands can pose a diagnostic dilemma in evaluation of surgical biopsies of these large ducts to rule out cholangiocarcinoma. Clues to malignancy are unequivocal perineural invasion, cribriform glandular structures, and pronounced nuclear pleomorphism and atypia .11  The peribiliary glands are grouped in lobular clusters, although this may be difficult to discern in the fibrotically distorted specimen.

The histologic staging schemes used for primary sclerosing cholangitis 1 are similar to those used for primary biliary cirrhosis.



Differential Diagnosis
As for primary biliary cirrhosis, the differential diagnosis for PSC changes with disease stage. Histologic overlap with primary biliary cirrhosis is occasionally a problem, although knowledge of the clinical setting, serologic tests, and radiographic appearance generally results in resolution. The portal inflammatory infiltrate in PSC is usually sparser than that seen in PBC, and florid duct lesions are not seen.

Chronic large duct obstruction may be difficult to distinguish from PSC, as extrahepatic obstruction from bile duct strictures is part of the pathologic process in this disease. Periductal fibrosis, bile ductular proliferation, and cholestasis are seen in both obstruction and PSC. However, in large duct obstruction from other causes, loss of interlobular bile ducts does not generally occur, and atrophic changes in ductal epithelium do not occur. The presence of numerous eosinophils in the portal inflammatory infiltrate also favors PSC.

Recurrent pyogenic cholangitis is a bacterial form of cholangitis that occurs almost exclusively in patients of Asian origin and is not likely to be confused with PSC. However, like PSC, many of the histologic features is this disorder are a result of bile stasis. Biliary parasites are present in some but not all cases. Repetitive bacterial infection and pigment stone formation result in biliary strictures, which in turn predispose to infection and more stone formation. Large intrahepatic ducts are scarred, thickened, and contain biliary sludge and stones. Microscopically, fibrosis and inflammation are present in the walls of large ducts. Small portal tracts show acute cholangitis, portal edema, and varying degrees of fibrosis .12  Cholangiocarcinoma arising in large stone-bearing ducts may complicate the disease. Inflammatory pseudotumors have also been reported in recurrent pyogenic cholangitis .13 

In pediatric patients with PSC, overlap of clinical and histopathologic features with autoimmune hepatitis may occur ;14  such overlap syndromes are rarer in adults but occur in approximately 7% of patients with PSC .15  Although alkaline phosphatase is usually elevated adults with PSC, normal alkaline phosphatase levels may be seen in children with the disease; in one study of 32 children with PSC, 15 had normal alkaline phosphatase levels at presentation .14  Most pediatric patients with PSC will also have ulcerative colitis (55%), although this figure is less than the commonly quoted 70% in adults. The cholangiogram may show very subtle irregularity of bile ducts, without overt stricture formation, and predominance of intrahepatic disease is common in childhood PSC. Concentric periductal fibrosis is rarely seen in biopsies from children; instead, the most notable feature is the loss of interlobular bile ducts, which often seem to vanish without a trace. The portal tracts may contain a dense mononuclear inflammatory infiltrate, with piecemeal necrosis and scattered plasma cells, further resembling autoimmune hepatitis. It has been suggested that autoimmune hepatitis and sclerosing cholangitis are similar in prevalence in pediatric patients and may represent different ends of a spectrum of autoimmune disease in this population .16  A high index of suspicion on the part of the gastroenterologist and the pathologist is often necessary to make the diagnosis of PSC in the pediatric patient.

Secondary sclerosing cholangiopathies
Other causes of biliary strictures are intrahepatic artery chemotherapy, immunodeficiency syndromes, and Langherhans cell histiocytosis. Hepatic artery infusion of floxuridine for treatment of hepatic metastases from colorectal carcinoma has been associated with a sclerosing cholangitis-like lesion resulting in hepatic failure. The etiology of these changes may be ischemic rather than toxic, as the bile ducts are supplied by the hepatic artery .17  Although treatment regimens now attempt to minimize the risk of this complication, one study reported a 1 year-rate of sclerosing cholangitis of 25% .18 

Langerhans' cell histiocytosis may present with isolated hepatic involvement or with involvement of other organ systems, most commonly lymph node and skin. In one recent study, 7 of 9 cases demonstrated injury to small and medium intrahepatic bile ducts by infiltrating Langerhans' cells .19  Concentric periductal fibrosis similar to that of primary sclerosing cholangitis was a feature of most cases, and bile ductular proliferation was often prominent. Of note, two cases with a PSC-like pattern of injury had no detectable Langerhans cells in the liver, and the diagnosis was established by biopsy of extrahepatic sites.

Infectious cholangiopathies may also mimic PSC. The most common infectious agents associated with this pattern of hepatic injury are cytomegalovirus and cryptosporidium, seen primarily in the AIDS population. The mechanism of bile duct injury in Cryptosporidial infection has recently been elucidated by studies using cultured biliary epithelial cells 20 and an animal model .21   In immunodeficient SCID mice, T cell cytokines appear to be required for inflammatory and sclerosing response to Cryptosporidial infection .21  Studies of cultured biliary epithelial cells have shown that the sporozoite form of the organism invades the luminal but not the basolateral surface of biliary epithelium; it resides in a tight-fitting vacuole formed by invagination of the plasma membrane, where it is able to undergo a complete reproductive cycle. Widespread apoptosis of epithelial cells occurs within hours after infection .20 

Clinical presentation of AIDS-related cholangiopathies is variable, ranging from asymptomatic to severe right upper quadrant pain; many patients will also have diarrhea as the infectious agents are also enteric pathogens. The most common organism is Cryptosporidium, but microsporidial species, Cyclospora, and mycobacterial avium complex are also biliary pathogens in this setting .22  Periampullary small bowel biopsies, bile duct brushings, or biopsies of the common bile duct are commonly used for diagnosis. Cholangiocarcinoma arising in the setting of AIDS-related cholangiopathy has been reported .23 

Specimen Pathogens Stains/Special Studies
Bile or duodenal aspirate Cryptosporidia
Microsporidia
MAI
CMV 		Papanicolaou (24)
Modified acid fast
Giemsa
Chromotrope 2R
Diff-Quik not recommended
Bile duct brushings As above EM for microsporidia
Biopsy of ampulla, small bowel As above Cryptosporidia easily visualized on H&E- 4 micron spheres on apical enterocyte surface
Microsporidia seen as 2-3 micron apical inclusions in enterocyte; trichrome stain useful


Some children with primary immunodeficiency develop sclerosing cholangitis. While many of these cases are undoubtedly related to persistent biliary tract infections, in others no infectious agent has been demonstrated. In one report of 56 children with PSC, 8 (14%) had a primary immunodeficiency syndrome, associated with cryptosporidial infection in 3, cytomegalovirus in 3, and no demonstrable organisms in 2 .25  In our practice, we have seen PSC-like lesions in two children with immunodeficiency: one with severe combined immunodeficiency treated with bone marrow transplantation, and one with common variable immunodeficiency.

References

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