Introduction
This course will provide a diagnostic framework for evaluating selected inflammatory, neoplastic, and
congenital disorders of the biliary system, with emphasis on clinicopathologic correlation. Disorders of
the bile ducts often present considerable diagnostic difficulty for the practicing pathologist, and
interpretation of biopsies and resection specimens with these lesions is best undertaken through
consideration of possible differential diagnoses and full knowledge of the clinical setting. However, in
the real world, we pathologists are often not provided with complete clinical information, and in this
case familiarity with various patterns of bile duct injury may help narrow the differential diagnosis.
Most of the discussion will focus on more common diseases affecting the biliary tree, such as primary
biliary cirrhosis, but rarer entities that provide insight into biliary pathology will also be included.
In addition to the references listed in the syllabus, the following textbooks on liver disease and
pathology may be helpful:
- Lee, RG. Diagnostic Liver Pathology. St. Louis : Mosby-Year Book, Inc, 1994.
- MacSween RNM, Burt AD, Portmann BC , et al (Eds). Pathology of the Liver.
4th ed. London : Churchill Livingston, 2002.
- Schiff ER, Sorrell MF, Maddrey WC (Eds). Diseases of the Liver. 8th ed.
Philadelphia: Lippincott-Raven, 1999.
- Sherlock S and Dooley J. Diseases of the Liver and Biliary System. 10th ed. London
: Blackwell Science Inc, 1997.
Normal Anatomy and Physiology
Bile excretion starts in the canaliculi formed between neighboring hepatocytes. The canaliculi form
continuous biliary channels that empty into ductular structures at the periphery of portal tracts. These
tiny ductules, also known as cholangioles or canals of Hering, are inconspicuous in normal liver. The
canals of Hering are by definition narrow tubular channels near portal tracts that are partially lined by
hepatocytes and partially by cholangiocytes (1) . They in turn drain into bile ductules that span the portal tract/parenchymal
interface to drain into the interlobular bile ducts , which measure approximately 20 to 80 microns in
outer diameter and located in the portal tracts. The normal ratio of bile ducts to portal tracts is
approximately 2 (2), and most hepatic artery branches will be accompanied by a bile duct. If more than
20 to 30% of arteries are unaccompanied by bile ducts, the possibility of a decrease in the number of
interlobular bile ducts (ductopenia) should be considered. The bile duct and hepatic artery branch are
roughly the same size and appear cut in the same plane in histologic preparations. Septal bile ducts are
larger than interlobular bile ducts, with an internal diameter of 100 microns (0.1 mm) or more, and join
to form segmental bile ducts. These larger ducts anastomose to form the large intrahepatic bile ducts at
the hepatic hilum. The right and left hepatic ducts combine to form the common hepatic duct. The common
bile duct is formed from the union of the cystic and the common hepatic duct and opens into the duodenal
lumen at the ampulla of Vater. The fibrous walls of larger bile ducts, both intrahepatic and
extrahepatic, contain glandular elements, the mucinous peribiliary glands, which may become distorted in
fibrosing and inflammatory conditions. Care should be taken not to confuse these mucinous glands with
well differentiated adenocarcinoma.
The bile ducts are lined by a single layer of cuboidal to columnar epithelial cells, the
cholangiocytes, which represent only about 3% to 5% of the cells of the liver (3). These duct cells
function with hepatocytes to form a bile secretory unit, and up to 40% of basal bile flow in the human
may be produced by duct cells (4). Like hepatocytes, cholangiocytes exhibit considerable functional
heterogeneity (5). They play an active role in biliary catabolism of glutathione, in uptake and
metabolism of solutes such as glucose and amino acids, and in transepithelial transport of anions such as
Cl- and HCO-3 (6). Biliary epithelial cells secrete IgA and normally express
Class I MCH antigens. Class II MHC antigens are not expressed on normal biliary epithelial cells but may
be seen in a variety of immunologically mediated disease states affecting the bile ducts, such as
allograft rejection, graft-versus-host disease, primary sclerosing cholangitis, and primary biliary
cirrhosis. Under the influence of cytokines such as IL-1 and TNF- a , bile duct epithelial cells can
also produce IL-8 and monocyte chemotactic protein-1, promoting recruitment of neutrophils and
lymphocytes to portal tracts (7).
Blood supply to the intrahepatic bile ducts is via the hepatic artery. A peribiliary vascular plexus
allows countercurrent exchange of ions between blood and bile, and allows modulation of bile composition
through secretion and resorption of water and electrolytes. This plexus can be visualized in the fibrous
walls of septal and larger bile ducts as a chain-like inner layer of capillaries and variable
intermediate and outer layers of capillaries, small arteries and veins. Normal interlobular bile ducts
have one to two small vessels adjacent to the bile duct basement membrane (8). On a practical note,
this single blood supply to the bile ducts means that ductal epithelium is susceptible to ischemic injury
in hepatic artery thrombosis, and ischemic injury may contribute to bile duct loss in chronic rejection
of the hepatic allograft.
From Reference 1:
References
- Saxena R, Theise ND, Crawford JM. Microanatomy
of the human liver- exploring the hidden interfaces. Hepatology 30: 1339-46, 1999.
- Crawford AR , Lin XZ, Crawford JM. The normal adult human liver biopsy: a quantitative reference standard.
Hepatology 28:323-31, 1998.
- Roberts SK, Ludwig J, LaRusso NF. The pathobiology of biliary epithelia. Gastroenterology 112:269-79, 1997.
- Nathanson MH, Boyer JL. Mechanisms and regulation of bile secretion. Hepatology 14:551-66, 1991.
- Kanno N, LeSage G, Glaser S, Alvaro D, Alpini G. Functional heterogeneity of the intrahepatic biliary epithelium. Hepatology 31:555-61, 2000.
- Fitz JG, Cohn JA. Biology and pathophysiology of CFTR and other Cl- channels in biliary epithelial cells. In: Sirica A, Longnecker D (eds).
Pathobiology of Intrahepatic Biliary and Pancreatic Duct Cells. Marcel-Dekker, 1996.
- Reynoso-Paz S, Coppel RL, MacKay IR, et al. The immunobiology of bile and biliary epithelium. Hepatology 30:351-7, 1999.
- Kobayashi S, Nakanuma Y, Matsui O. Intrahepatic peribiliary vascular plexus in various hepatobiliary diseases: a histological survey. Hum Pathol
25:940-6, 1994.
Pathology of Cholestasis
The process of bilirubin formation and bile secretion is complex and involves multiple cell types.
It is therefore not surprising that cholestasis is a feature of many disorders involving the liver and
bile ducts. For instance, cholestatic disorders may be due primarily to hepatocyte dysfunction, as in
some examples of drug-induced hepatic injury; impaired transport of bile into the canaliculus; disorders
such as primary biliary cirrhosis that affect primarily the small intrahepatic bile ducts; diseases
affecting the larger intra- and extrahepatic bile ducts, such as primary sclerosing cholangitis; or
conditions affecting the common bile duct or ampulla of Vater. Accumulation of bile products within the
liver results in morphologic patterns of injury that are not difficult to recognize but are unfortunately
not specific.
Morphologic patterns of bile accumulation in the liver may be broadly divided into acute cholestasis
and chronic cholestasis.
Causes of Cholestasis
| Cholestasis | Intrahepatic | Extrahepatic |
| Acute | Drug-induced
Cholestasis of pregnancy
Benign recurrent cholestasis
Sepsis | Large duct obstruction |
| Chronic | Primary biliary cirrhosis
Primary sclerosing cholangitis
Sarcoidosis
Drug-induced
Progressive familial cholestasis | Large duct obstruction, often low grade or intermittent
Primary sclerosing cholangitis |
The defining morphologic feature of acute cholestasis is the accumulation of bile pigment in zone 3,
most characteristically in canaliculi but also involving hepatocytes and Kupffer cells as the cholestasis
becomes progressively severe. Bile pigment may on occasion be confused with other brown pigments that
accumulate within the liver; however, in comparison to lipofuscin and iron, bile pigment is less granular
and refractile, and has a brown-green hue. Iron is more commonly found in periportal hepatocytes.
Lipofuscin is preferentially located in zone 3 hepatocytes and may be quite prominent in livers of
elderly persons, but the lack of associated canalicular bile plugs and the granularity of the pigment are
diagnostic clues.
Bile ductular proliferation is often but not invariably present in acute cholestasis, but is not
specific for cholestatic injury. Proliferating bile ductules may be found at the perimeter of portal
tracts in any condition causing periportal fibrosis, but when ductular proliferation is especially
prominent and accompanied by canalicular cholestasis, biliary obstruction should be considered. In
contrast to the interlobular bile duct, these serpiginous ductular structures are found at the periphery
of the portal tract and are not sectioned in the same profile as the branch of the hepatic artery.
Proliferating bile ductules invariably attract neutrophils, and the presence of acute inflammatory cells
should not lead to a diagnosis of acute cholangitis, which is defined as acute inflammation involving
interlobular bile duct epithelium. Periductal edema is more specific for biliary obstruction than
proliferating bile ductules but is often not present. Other near-pathognomonic features of large bile
duct obstruction are bile lakes and infarcts due to rupture of bile ducts with resulting extravasation of
bile, and ductal cholestasis; unfortunately these changes are rarely seen.
The histologic hallmark of chronic cholestasis is feathery degeneration of hepatocytes (cholate
stasis), due to accumulation of bile salts within the cytoplasm, imparting a pale appearance to
periportal or periseptal hepatocytes. Canalicular bile plugs are scarce to non-existent. Periportal and
periseptal hepatocytes also accumulate copper in chronic cholestasis, and this copper storage can be
demonstrated with a variety of special stains. Orcein or aldehyde fuchsin stains, which are generally
used to demonstrate accumulation of hepatitis B surface antigen, will also highlight increased copper
binding protein, which, like Hepatitis B surface antigen, contains a large number of sulfhydryl groups.
Positive staining is seen as granular deposition in periportal hepatocytes. Any of the special stains
for copper itself, such as rhodanine or rubeanic acid stain, may also be used. This copper accumulation
is not specific, but when found in a pre-cirrhotic liver biopsy is highly suggestive of chronic
cholestasis, if rare entities such as Wilson's disease and Indian childhood cirrhosis have been excluded.
Mallory's hyaline may also be found in periportal hepatocytes in chronic cholestasis, and is
morphologically indistinguishable from that found in alcoholic liver disease.
| Feature | Acute Cholestasis | Chronic Cholestasis |
| Bile pigment | Prominent; in zone 3.
In canaliculi, hepatocytes, Kupffer cells | Rare; when present, in zone 1 |
| Bile ductular proliferation | Often present | Stage-dependent |
| Cholate stasis | Rare early in disease | Prominent, zone 1 |
| Other features | Periductal edema in obstruction | Increased copper storage; Mallory's hyaline may be present in periportal hepatocytes |
Useful Clinical Information in Evaluation of Cholestasis in Liver Biopsies
| Acute Cholestasis Pattern | Chronic Cholestasis Pattern |
| ERCP useful if large duct obstruction suspected | ERCP useful if PSC or chronic obstruction suspected |
| Hepatic ultrasound may show dilated bile ducts in obstruction | Other medical conditions: inflammatory bowel disease, Sjogren's syndrome, etc. |
| ? sepsis, if periportal cholangioles contain bile | Serologic tests: antimitochondrial antibody;
ANA for overlap syndromes |
| Drug history | Drug history |
Useful Stains in Evaluation of Bile Duct Lesions
| Stain | Shows | Disease |
| PAS with diastase | Basement membrane | Bile duct injury; PBC |
| Trichrome | Type I collagen | Useful for identification of bile ducts |
| Shikata stain (orcein, aldehyde fuchsin) I | ncreased copper binding protein in chronic cholestasis | PBC, PSC |
| Cytokeratin (AE1/AE3 or CK7) | Biliary epithelium (bile ducts express CK 7, 8, 18, 19) | Ductopenia |
| EMA | Biliary epithelium | Ductopenia |
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.
Click on each slide thumbnail image for an enlarged view:
Slide 1
Primary Biliary Cirrhosis
A damaged medium-sized interlobular bile duct is surrounded by a dense mononuclear inflammatory infiltrate. Lymphocytes focally infiltrate bile duct epithelium.
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Slide 2
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.
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Slide 3
Primary Biliary Cirrhosis, Florid Duct Lesion
The bile duct epithelium shows degenerative changes such as vacuolization and cytoplasmic granularity.
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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.
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.
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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.
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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.
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This 79 year old man living in a nursing home had long-standing
chronic liver disease. Viral serologies and anti-mitochondrial and antineutrophil antibodies were
negative. ERCP done at an outside institution was reported as normal. Two first degree relatives also
had chronic liver disease of unknown etiology. Total bilirubin concentration was 6.6 mg/dL, alkaline
phosphatase was 413 IU/L, ALT 78 U/L, and AST 250 U/L. The patient also had diabetes mellitus and
chronic obstructive pulmonary disease. He died during hospice care; an autopsy limited to liver and
pancreas was performed.
Click on each slide thumbnail image for an enlarged view:
Slide 7
Adult Idiopathic Ductopenia
The liver from this 79 year old man shows a biliary pattern of cirrhosis, with "jigsaw puzzle piece" outlines to the regenerating nodules. The extrahepatic and large intrahepatic ducts were normal.
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Slide 8
Loss of Interlobular Bile Ducts in Adult Idiopathic Ductopenia
No residual bile duct is identified in many of the portal tracts in this case. Nodular scars suggestive of primary sclerosing cholangitis are not present. Proliferating bile ductules are present at the periphery of the portal tracts, but dilated biliary channels suggestive of a ductal plate malformation are not seen.
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Slide 9
Recurrent Pyogenic Cholangitis
Small portal tracts contain a mixed inflammatory infiltrate with numerous neutrophils. Portal edema and fibrosis may also be seen.
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Slide 10
Hyperplastic Changes in Bile Duct Epithelium In Recurrent Pyogenic Cholangitis
Ductal epithelium shows crowding and hyperplastic changes without nuclear pleomorphism or hyperchromasia. Cholangiocarcinoma may complicate recurrent pyogenic cholangitis, and is associated with biliary stones.
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This 27 year old man developed fulminant hepatic failure of
unknown etiology and underwent liver transplantation. Two months later he presented with a slight fever
(T=100 degrees F). Serum ALT was 1419 U/L, AST 772 U/L, total bilirubin 6.2 mg/dL, and alkaline
phosphatase was 293 U/L. Cyclosporine level was low at 50 ng/mL. A liver biopsy was performed.
Click on each slide thumbnail image for an enlarged view:
Slide 11
Acute Rejection in Liver Allograft
A mixed portal inflammatory infiltrate composed of mononuclear cells and scattered eosinophils and neutrophils is present. The interlobular bile ducts are infiltrated by lymphocytes; reactive changes in biliary epithelium such as nuclear enlargement and cytoplasmic vacuolization may also be seen.
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Slide 12
Acute Rejection in Liver Allograft
In endothelialitis, inflammatory cells, predominantly lymphocytes, undermine the endothelium, resulting in detachment of endothelial cells from the underlying connective tissue. Endothelialitis is relatively specific for acute rejection, but is often not present in milder cases of rejection.
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This 16 month old male child with severe combined immunodeficiency received a haploidentical bone marrow transplant. Skin rash and diarrhea developed at
day 10 post transplant. Marked abdominal distension developed on day 16. Chest x-ray showed worsening
bilateral interstitial infiltrates. The patient died on day 21 post transplant.
Click on the slide thumbnail image for an enlarged view:
Slide 13
Acute Graft-versus-host Disease
Interlobular bile ducts are the primary target in the liver in acute graft-versus-host disease. A mild lymphocytic infiltrate is often seen around the affected bile ducts, but inflammation is often minimal in relationship to the degree of bile duct injury. The bile duct epithelial cells in this example are sloughed and show degenerative changes. Lymphocytes may also infiltrate biliary epithelium.
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This previously healthy twelve year old girl was treated with a preparation containing
phenobarbital after she developed intermittent crampy abdominal pain and fever. Two days later she
developed a skin rash that progressed to toxic epidermal necrolysis. Respiratory distress required
intubation; open lung biopsy obtained on Day 19 of admission showed severe diffuse alveolar damage in the
organizing phase. Hepatomegaly was noted on Day 10; peak aboldities in liver tests observed over the
next few days were ALT 1156 U/L, alkaline phosphatase 1743 U/L, total bilirubin 28 mg/dL, conjugated
bilirubin 26.8 mg/dL. A liver biopsy was performed on day 19. The patient died on hospital day 99 of
progressive pulmonary and renal failure. A representative section of liver from the autopsy is provided.
Click on each slide thumbnail image for an enlarged view:
Slide 14
Loss of Bile Ducts Associated with Drug Therapy and Toxic Epidermal Necrolysis
On low power, minimal portal and lobular inflammation is seen; perivenular and sinusoidal fibrosis is present in zone 3, and scattered canalicular bile plugs are present.
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Slide 15
Loss of Bile Ducts Associated with Drug Therapy and Toxic Epidermal Necrolysis
The portal tracts are devoid of bile ducts; no significant inflammatory infiltrate is seen.
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Slide 16
Bile Duct Injury Associated with Antibiotic Therapy
The portal triad contains a mixed inflammatory infiltrate. The interlobular bile duct is almost unrecognizable owing to heavy infiltration of duct epithelium by lymphocytes and neutrophils in this example of drug-induced cholestasis associated with amoxicillin/clavulanate (Augmentin) therapy.
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This 50 year old woman was in good health until 1994, when she developed esophageal variceal
bleeding. An arteriogram showed pre-sinusoidal portal hypertension. Serum liver tests were within
normal limits. Further work-up showed medullary sponge kidney. A mesocaval shunt was performed; this
liver biopsy was obtained during surgery.
Click on each slide thumbnail image for an enlarged view:
Slide 17
Congenital Hepatic Fibrosis
The hepatic parenchyma is distorted by fibrous expansion of portal tracts containing numerous abnormal biliary channels.
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Slide 18
Congenital Hepatic Fibrosis
Dysmorphic anastomosing biliary channels are arranged around the perimeter of the enlarged portal tracts.
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This 45 year old woman developed abdominal pain, post-prandial fullness and lower extremity
edema over several months. Physical exam revealed marked hepatomegaly. A CT scan of the abdomen
revealed near-total replacement of the right lobe of the liver by cystic lesions and several large cysts
in the left lobe. The kidneys also contained multiple cysts. The right lobe of the liver was resected.
Click on each slide thumbnail image for an enlarged view:
Slide 19
Polycystic Liver Disease
Multiple unilocular cysts of varying sizes are found in the liver in polycystic liver disease. Biliary hamartomas, or von Meyenburg complexes, are frequently found in the vicinity of the cysts and probably give rise to them by progressive accumulation of fluid.
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Slide 20
Polycystic Liver Disease
The cysts of autosomal dominant polycystic disease involving the liver are lined by a simple cuboidal to low columnar biliary-type epithelium.
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This 59 year old woman developed shaking chills and fever following cholangiogram. After
treatment with antibiotics, she underwent resection of the left lobe of the liver.
Click on each slide thumbnail image for an enlarged view:
Slide 21
Caroli's Disease
Involvement of the large intrahepatic bile ducts by the ductal plate malformation process gives rise to congenital dilatation of bile ducts in Caroli's disease. These dilated ducts are predisposed to bile stasis, stone formation, and infection.
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Slide 22
Bile Duct Epithelial Hyperplasia in Caroli's Disease
Biliary epithelial hyperplasia may be seen in ducts involved by Caroli's disease. Rarely, frank epithelial dysplasia, which may represent the precursor of cholangiocarcinoma, is seen.
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This 42 year old woman underwent liver transplantation for primary sclerosing cholangitis.
She had a long history of ulcerative colitis and was diagnosed with PSC seven years after colectomy for
UC. Cholangiogram showed beading of large bile ducts, with a dominant stricture near the hepatic hilum.
The patient underwent orthotopic liver transplantation. This section is from near the hilum of her
native liver.
Click on each slide thumbnail image for an enlarged view:
Slide 23
Perihilar Cholangiocarcinoma Arising in Primary Sclerosing Cholangitis
The typical cholangiocarcinoma is well to moderately differentiated, and the tumor cells closely resemble biliary epithelium. A dense desmoplastic stroma usually accompanies the tumor, even in cases not arising in primary sclerosing cholangitis.
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Slide 24
Perineural Invasion in Cholangiocarcinoma
Peri- and intraneural spread is common in cholangiocarcinomas and may serve as a helpful clue to diagnosis of malignancy in small specimens.
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This 62 year old woman presented to the emergency room with crushing chest pain, diagnosed
as angina, and was found to have an enlarged liver. Abdominal CT scan showed two cystic masses in the
liver and bilateral adrenal hyperplasia but no adenopathy. Positron emission scan showed two
metabolically active areas within one of the cystic masses. At surgery a small amount of mucoid ascites
was found. The cysti hepatic lesions were resected; this section is from the larger mass, which
measured 8.6 cm in greatest dimension.
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Slide 25
Adenocarcinoma Arising in Biliary Cystadenoma
Cytologically malignant cells forming cribriform and papillary structures infiltrate the cyst wall.
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Slide 26
Biliary Cystadenoma with Mesenchymal Stroma
The cysts of biliary cystadenoma are lined by simple columnar to cuboidal epithelium; goblet cells are occasionally seen. The underlying mesenchymal stroma may be densely packed and resemble ovarian stroma, a feature found exclusively in female patients.
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