Disorders of the Intra- and Extrahepatic Bile Ducts
Case 1 -
Primary Biliary Cirrhosis, Stage 2 (Periportal Stage)
Kay Washington, M.D., Ph.D.
Pathology, C-3321 MCN
Vanderbilt University Medical Center
Nashville, TN 37232-2561
This 50 year old woman had an 8 year history of pruritis, elevated alkaline phosphatase
levels, and a positive serologic test for anti-mitochondrial antibodies. The patient had esophageal
varices but had not suffered any episodes of bleeding. She developed debilitating fatigue and underwent
orthotopic liver transplantation.
The native liver was normal to slightly enlarged, with a subtle nodularity on
sectioning, without increased firmness. The extrahepatic bile duct was normal. On microscopic
examination, the portal tracts contain an increased number of mononuclear inflammatory cells, with
minimal piecemeal necrosis or interface hepatitis. The inflammatory infiltrate is composed predominantly
of small lymphocytes, with a sprinkling of eosinophils and plasma cells, and is centered about bile
ducts. Both medium-sized and small interlobular bile ducts are affected. In some areas, a granulomatous
component surrounds an injured bile duct and the duct epithelium shows degenerative changes such as
pyknosis and cytoplasmic vacuolization. Interlobular bile ducts are lost from some portal tracts, and
there is slight bile ductular proliferation. The portal tracts are slightly expanded by fibrous tissue,
without bridging. Minimal inflammation is seen in the lobules, and no canalicular or chronic cholestasis
Click on each slide thumbnail image for an enlarged view:
Primary Biliary Cirrhosis
A damaged medium-sized interlobular bile duct is surrounded by a dense mononuclear inflammatory infiltrate. Lymphocytes focally infiltrate bile duct epithelium.
Primary Biliary Cirrhosis, Florid Duct Lesion
Granulomatous destruction of bile ducts is a characteristic histologic hallmark of primary biliary cirrhosis, although granulomas are not seen in all cases and may be absent in late stages. Epithelioid macrophages may be loosely grouped in ill defined clusters or may form a sarcoid-like granuloma, as shown here.
Primary Biliary Cirrhosis, Florid Duct Lesion
The bile duct epithelium shows degenerative changes such as vacuolization and cytoplasmic granularity.
Diagnosis: Primary Biliary Cirrhosis, Stage 2 (Periportal Stage)
In primary biliary cirrhosis, the intrahepatic bile ducts are progressively
destroyed by a non-suppurative inflammatory process. The disease has distinctive clinical features,
being found primarily in women (90% of patients), mostly in the fifth to seventh decades. PBC is
probably autoimmune in etiology, judging by its association with other autoimmune disorders such as
Sjogren's disease and keratoconjuctivitis sicca, and may in some patients represent a generalized
disorder of lacrimal, salivary, and pancreaticobiliary small duct epithelia. Large intra- and
extrahepatic bile ducts are not affected. The most specific feature of PBC is the presence of
antimitochondrial antibodies in the serum of 90% of patients affected. Antibodies directed to the PDC-E2
antigen, a component of the pyruvate dehydrogenase enzyme complex present on the inner mitochondrial
membrane, are highly specific (96%) for PBC. Immunohistochemical staining shows that expression of
either PDC-E2 or a PDC-E2 mimic is increased in bile duct epithelial cells of PBC patients, and aberrant
luminal expression is seen. Recent reports suggest that the epitope recognized by antibodies producing
apical staining in biliary cells in primary biliary cirrhosis is the inner lipoyl domain of PDC-E2 (1) .
The exact mechanism by which AMA might be cytopathic to biliary epithelial cells remains to be
elucidated, however. The presence of serum AMA indicates a specific B-cell response to this
mitochondrial antigen; specific T cell responses are seen as well (2) . Other circulating autoantibodies
such as anti-smooth muscle and anti- nuclear antibodies and rheumatoid factor are often present.
Hypergammaglobulinemia with a selective elevation of IgM is often seen. An infectious etiology has been
postulated (2) , with recent reports of cloning of a retroviral sequence directly from biliary
epithelium from PBC liver (3) . Genomic analysis of differentially expressed gene s in bile duct cells
from PBC livers shows upregulation of genes in involved in signaling, mitochondrial function,
inflammation, and fibrosis (4) .
Most patients with PBC present with fatigue (21%) and pruritis (19%) (5) , the latter due to the
accumulation of bile salts. Many asymptomatic patients are now identified after screening tests show
elevation of serum alkaline phosphatase. Patients are rarely jaundiced early in the course of the
disease; indeed, the presence of bile pigment in a liver biopsy suspected of harboring low-stage PBC
should prompt a reconsideration of the diagnosis. PBC follows a progressive clinical course in most
patients, and most but not all asymptomatic patients will develop significant liver disease.
Survival is variable, but is generally from 6 to 12 years after presentation for symptomatic
patients. In one recent study, 26% developed liver failure by 10 years after diagnosis (5) .
Ursodeoxycholic acid is used for treatment in early stages; liver transplantation is the only effective
therapy for late stage disease.
The characteristic lesion of primary biliary cirrhosis is the so-called florid duct
lesion, sometimes also called chronic nonsuppurative destructive cholangitis (6) . Interlobular bile
ducts 40 to 80 microns in diameter are typically involved. In early stage PBC, the diagnostic lesions
may be focal and may not be sampled on needle biopsy. The three components of the florid duct lesion are
inflammation, injury to bile duct epithelial cells, and disruption of the bile duct basement membrane.
The inflammatory infiltrate is composed of lymphocytes, scattered eosinophils, macrophages, and a
variable number of plasma cells, and is intimately associated with the bile duct. The macrophages may be
dispersed throughout the portal inflammatory infiltrate or may be aggregated into loose clusters or
occasionally into well-formed granulomas. Granulomas and Kupffer cell aggregates may be present in the
lobule. In early stages, the inflammatory infiltrate is largely confined to the portal tract. The
biliary epithelial cells of injured bile ducts are swollen, and focally stratified, and may be
vacuolated. Lymphocytes commonly infiltrate bile duct epithelium. The basement membrane becomes
disrupted and fragmented, best visualized on PAS stain. Lytic necrosis, not apoptosis, appears to
account for most of the biliary epithelial loss (7) . In small portal tracts, bile ducts are often
absent and seem to have vanished without a trace, although aggregates of lymphocytes or PAS-positive
basement membrane material may mark their former location. Canalicular cholestasis is not a feature of
early stage PBC.
As the duct destruction progresses, bile ductular proliferation accompanied by fibrosis develops at
the periphery of portal triads, and portal tracts enlarge by this process of biliary piecemeal necrosis.
In some cases the inflammatory infiltrate spills over into the adjacent parenchyma, and lymphocytic
piecemeal necrosis may mimic chronic hepatitis. At this stage the changes of chronic cholestasis begin
to appear, with swollen and rarefied periportal hepatocytes and accumulation of copper. As periportal
fibrosis progresses, portal-portal fibrous bridges are formed. Bile ductular proliferation often
subsides in late stage PBC, and in the cirrhotic stage little ductular or ductal epithelium can be
identified. The cirrhosis has a typical biliary pattern, in which the nodules have an irregularly shaped
"jigsaw puzzle piece" profile.
Histologic Differential Diagnosis
The term "AMA-negative PBC" or " autoimmune cholangitis" has been
applied to cases that are clinically, histologically, and biochemically compatible with PBC except for
the lack of identifiable antimitochondrial antibodies. More sensitive testing using cloned mitochondrial
antigens such as a triple hybrid recombinant molecule may identify AMA in some patients previously
thought to be seronegative (2) . In retrospective studies, no significant differences between patients
with PBC and these AMA-negative patients have been described (8-12) . However, a recent prospective
study describing 20 patients with autoimmune cholangitis reports that these patients have higher serum
levels of AST and bilirubin and lower serum IgM than patients with classic PBC (13) . Antibodies to
carbonic anhydrase are present in the serum of patients with autoimmune cholangitis in some studies, but
have not been discriminatory in others. Of the 15 patients with autoimmune cholangitis with biopsies
reported in one study, six had a PBC-like and 7 had a PSC-like pattern of injury, suggesting that
"autoimmune cholangitis" may represent a mixed group of autoimmune disorders at varying stages, or
possibly a transition state (13) . AMA-negative patients were slightly younger in one group (50 vs. 55
years) but were otherwise indistinguishable (8) . Although data are largely lacking, it is though that
the response to ursodeoxycholic acid (UDCA) therapy in these patients is the same as for those who are
AMA-positive, and there are accordingly no differences in the treatments prescribed for these two groups
at the present time.
The differential diagnosis for PBC depends on the stage of the disease. In stage 1 and 2 disease,
portal inflammation, piecemeal necrosis and bile ductular proliferation may mimic chronic hepatitis,
particularly hepatitis C. Bile duct damage is less prominent in chronic hepatitis and bile duct loss is
rarely seen, but lymphocytic infiltration of bile duct epithelium is often a feature of hepatitis C. A
recent study using immunostaining for cytokeratin 7 reports that absence of central interlobular bile
ducts and lack of a lumen in preserved ducts, presumably due to cell swelling, are features of primary
biliary cirrhosis but not chronic hepatitis (14) . Clinical information such as antimitochondrial
antibody status and serologic markers for viral hepatitis is helpful in most cases.
It may be more difficult to distinguish autoimmune hepatitis from PBC, however, and indeed this
distinction may prove impossible on histologic grounds. Because treatment for autoimmune hepatitis
differs from that for primary biliary cirrhosis, accurate diagnosis is important. Difficulties arise
because the portal inflammatory infiltrate of PBC often contains numerous plasma cells, and infiltration
of bile duct epithelium by lymphocytes is not uncommon in autoimmune hepatitis, if looked for, and some
degree of bile duct injury is often present. Although non-destructive bile duct lesions are quite common
in autoimmune hepatitis, duct loss is generally not a feature, and granulomatous bile duct destruction is
not seen. Serum alkaline phosphatase, cholesterol, and IgM levels are elevated to higher levels in PBC.
To add to the problem, some patients with clinical and histologic features of autoimmune hepatitis will
have serum anti-mitochondrial antibodies. In some cases this is caused by misreading of
immunofluorescence-type tests (confusing anti-LKM antibodies with antimitochondrial antibodies). In
other patients, however, the AMA is truly positive, but usually in low titer. Serologic markers may not
be definitive in such cases, as patients with PBC may have a positive ANA and patients with autoimmune
hepatitis may have a low titer AMA. The term "overlap syndrome" is used for cases of autoimmune liver
disease with both cholestatic and hepatitic features that do not fit readily into the usual diagnostic
categories (15,16) . Liver biopsies in such cases show features of both PBC (granulomatous
inflammation and bile duct lesions) and autoimmune hepatitis (piecemeal necrosis and spotty hepatocyte
necrosis) (17) . In addition to these cases with "overlapping" simultaneous features of both diseases,
rare patients who switch from one disease to another over time are reported (18) .
The existence of this overlap syndrome between PBC and autoimmune hepatitis is generally recognized,
although investigators disagree over exact classification. Some researchers (15) consider these
patients to have PBC, based on duct destruction and presence of AMA, and have proposed that these cases
be classified as "PBC, hepatitic form". Others have concluded that overlap of PBC and autoimmune
hepatitis is not rare, and that combination therapy with ursodeoxycholic acid (UDCA) and steroids is
indicated in most of these patients to obtain a biochemical response (16) . In this recent study of 12
such patients, the authors found that "overlap " cases constituted 9% of 130 consecutive patients with a
diagnosis of PBC. Because of the observation that some patients diagnosed with PBC have a flare of
hepatitic activity when treated with ursodeoxycholic acid, it has been proposed that response to UDCA may
unmask the hepatitis component in overlap patients (16) . Further complicating the issue, some
investigators suggest that features of AIH in PBC may be transient (19) .
On a practical note, what does the surgical pathologist need to know about overlap syndrome? Exact
classification of these patients may change as we learn more about the pathophysiology of these diseases.
The term "overlap syndrome" should not be overused by applying it to otherwise typical cases of PBC with
prominent interface hepatitis. In general, in low-titer AMA-positive patients, if the liver biopsy shows
features typical of autoimmune hepatitis, such as prominent piecemeal necrosis, numerous plasma cells in
the inflammatory infiltrate, and lobular hepatitis, without prominent bile duct destruction, and liver
tests favor a hepatitic process over chronic cholestasis, clinicians will often consider this patient to
have autoimmune hepatitis and prescribe immunosuppressive therapy such as corticosteroids. Since UDCA
has few side effects, it may be used as well. True overlap syndromes do occur but are fairly rare,
constituting less than 10% of PBC patients (16) , and most patients with clinical or histologic features
that strongly suggest a component of autoimmune hepatitis will be treated with a course of
Distinction of PBC from those cases of sarcoidosis with destruction of bile ducts by granulomas may
be difficult (20,21) . In a study of 100 cases of hepatic sarcoidosis, 58% of the biopsies showed
evidence of cholestasis, generally feathery degeneration and increased copper storage (20) . Nineteen of
these biopsies had bile duct lesions similar to those seen in PBC. The granulomas of sarcoidosis tended
to be better formed and more numerous than those of PBC. The lack of AMA positivity and the presence of
pulmonary involvement also favor a diagnosis of hepatic sarcoidosis. Of note, sarcoidosis may also cause
intrahepatic biliary strictures that have cholangiographic features resembling primary sclerosing
cholangitis (22) .
The Surgical Pathology Report in PBC
The following features may be useful to note in the surgical
pathology report in primary biliary cirrhosis:
- Description of bile duct lesion: granulomatous, lymphocytic, loss of bile ducts
- Nature of portal inflammatory infiltrate: are plasma cells prominent?
- Presence of piecemeal necrosis or interface hepatitis
- Bile ductular proliferation
- Lobular activity: lymphocytes, granulomas, Kupffer cell aggregates, hepatocyte injury
- Cholestasis: canalicular bile plugs (rare), feathery degeneration, Mallory's hyaline (late stage)
- Extent of fibrosis (stage)
Histologic Staging of Primary Biliary Cirrhosis
The value of histologic staging in assessing
prognosis in PBC is debatable, given the lack of uniformity of duct loss and fibrosis in the liver in
this disease. However, the presence of portal-portal bridging fibrosis on biopsy has been shown to be a
poor prognostic sign. Several staging schemes have been described, and there is little practical
difference between the two that are most commonly employed, those described by Scheuer (23) and Ludwig
(24) . In stage 1 disease, damage to interlobular bile ducts is seen in the form of the florid duct
lesion. In stage 2, the effects of duct injury result in extension of the process to involve the
periportal areas, and ductular proliferation, probably representing a compensatory reaction to bile duct
loss, is prominent. Stage 3 is characterized as a scarring or precirrhotic stage, with bridging
fibrosis. Stage 4 is cirrhosis.
Comparison of Histologic Features of PBC, PSC, Chronic Hepatitis, and Sarcoidosis
|Feature ||PBC ||PSC ||Chronic hepatitis ||Sarcoidosis|
|Chronic cholestasis ||prominent, late ||prominent, late ||trace, late ||variable|
|Copper storage ||variable ||variable ||trace ||variable|
|Duct loss ||extensive ||extensive ||rare ||variable|
|Granulomas ||variable ||rare ||rare ||key feature|
|Interface hepatitis ||variable ||variable ||key feature ||absent|
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