Description
Recurrent pyogenic cholangitis (RPC), also known as oriental cholangiohepatitis, is a disease characterised by repeated episodes of cholangitis, commonly due to bacterial infections, along with pigment stone formation and biliary strictures. It leads to recurrent fever, abdominal pain, and jaundice, hence the classic symptom triad known as Charcot’s triad.
Pathogenesis
The exact pathogenesis of RPC is not entirely understood but is likely multifactorial. One key factor is the infestation with liver flukes like Clonorchis sinensis and Opisthorchis viverrini. Ingestion of the eggs of these parasites from undercooked fish leads to biliary tract infestation. The flukes’ metabolic products cause inflammation and stasis of bile, leading to repeated bacterial infections and stone formation.
Epidemiology, Risk Factors & Associations
RPC is most common in Asian countries, particularly in China, Korea, and Southeast Asia (correlating with the prevalence of liver fluke infestations). It has been reported to affect up to 10% of the population in certain high-risk areas. Risk factors include ingestion of undercooked fish, poor sanitation, and lack of access to healthcare.
Clinical Features
Patients with RPC often present with the classic Charcot’s triad of recurrent fever (due to cholangitis), abdominal pain (often in the right upper quadrant or epigastrium), and jaundice. Other symptoms can include chills, nausea, vomiting, weight loss, and hepatomegaly.
Complications
Complications of RPC can be severe and include liver abscess, biliary cirrhosis, portal hypertension, cholangiocarcinoma, and sepsis.
Pathological Features
Morphology & Histopathology
The intrahepatic and extrahepatic bile ducts often demonstrate thickening and fibrosis, with dilatation and strictures. Pigment stones are typically present within the ducts. Histologically, there is inflammation of the biliary epithelium, fibrosis, and potentially malignant transformation over time.
- Pigment stones are a type of gallstone composed mainly of bilirubin, a byproduct of red blood cells broken down by the liver. They get their name from their dark colour, usually black or brown. These stones form when there’s an imbalance in the composition of bile, particularly when the liver excretes too much bilirubin or when there’s a reduction in bile flow, leading to bile stasis. Conditions that lead to increased red blood cell turnover, like haemolytic anaemia, or those causing decreased gallbladder motility or bacterial infection of the biliary tract, like recurrent pyogenic cholangitis, increase the risk of pigment stone formation.
Radiological Features
Radiological findings in RPC often show evidence of biliary tract dilatation, strictures, and stone formation.
Radiological Features
General Features
- Intrahepatic and extrahepatic biliary dilatation with multiple biliary calculi (typically measure 1-4 cm in size). A combination of pigment stones and biliary sludge is commonly observed.
- Often affects the lateral segment of the left lobe or, less commonly, the right posterior segment. In later stages of the disease, it may involve all biliary ductal segments, including the common bile duct (CBD).
ERCP
- Dilated intrahepatic and extrahepatic bile ducts with disproportionate dilatation of the extrahepatic duct.
- Rapid tapering of dilated intrahepatic ducts, exhibiting an arrowhead configuration, decreased arborisation of peripheral ducts, and short-segment bile duct strictures.
- Common duct and intrahepatic duct stones.
- Filling defects within biliary ductal segments due to strictures of intrahepatic ducts (the ‘missing duct sign’).
CT
- Disproportionate dilatation of extrahepatic and central intrahepatic bile ducts: the CBD may be markedly enlarged.
- Decreased arborisation of peripheral ducts and multiple biliary strictures.
- Localised dilatation of bile ducts, especially in the left hepatic lobe and right posterior hepatic lobe.
- Ductal wall hyperenhancement and heterogeneous liver enhancement can occur during acute cholangitis exacerbation.
- Pneumobilia is common and may be related to passage of stones through the ampulla, prior biliary procedures, or, less commonly, cholangitis due to gas-forming organisms.
- Hepatolithiasis and choledocholithiasis are often observed: approximately 90% of stones are hyperdense to liver.
- Distribution of dilated ducts unrelated to the location of calculi.
- Associated with pyogenic liver abscesses, bilomas, steatosis, segmental atrophy with chronic biliary obstruction, and cholangiocarcinoma.
- Atrophy most often affects the left lateral segment of the liver.
- Over time, scarring, atrophy, and capsular retraction of the liver can produce a cirrhotic morphology of the liver.
MRI
- Dilatation of intrahepatic and extrahepatic bile ducts, with disproportionate dilatation of the extrahepatic and central intrahepatic ducts.
- Magnetic Resonance Cholangiopancreatography (MRCP) can clearly illustrate decreased arborisation of peripheral ducts, multiple intrahepatic biliary strictures, and rapidly tapering intrahepatic ducts (the ‘arrowhead sign’).
- Stones with low T2-weighted imaging (T2WI) signal can be seen within both intrahepatic and extrahepatic ducts. These stones are primarily pigmented and may appear diffusely hyperintense or peripherally hyperintense (centrally hypointense) on T1-weighted imaging (T1WI).
- Sites of dilated bile ducts may not be closely related to sites of bile duct stones.
- Lobar or segmental liver parenchymal atrophy associated with sites of greatest biliary dilatation. The atrophic liver may appear hypo-, iso-, or hyperintense on T1WI and mildly hyperintense on T2WI relative to normal liver.
US
- Disproportionate dilatation of extrahepatic and central intrahepatic bile ducts.
- Hepatolithiasis is seen in approximately 90% of cases.
- Intrahepatic stones may be difficult to distinguish from pneumobilia
- Prominent periportal echogenicity.
- Focal hypoechoic parenchymal lesions could represent liver abscess, biloma, or cholangiocarcinoma.
NM
- White Blood Cell (WBC) scan: Positive for cholangitic liver abscesses.
Cholangiography
- Similar findings to ERCP, including dilated intra- and extrahepatic ducts with filling defects (stones).
- An arrowhead deformity of rapidly tapering intrahepatic ducts is observed.
Grading and Staging
There is no specific grading or staging system for RPC. The severity of the disease is usually assessed based on the extent of biliary tract involvement, number and severity of episodes of cholangitis, and presence of complications.
Differential Diagnosis
- Choledocholithiasis: Presents with similar clinical features but typically lacks the recurrent nature and the degree of biliary tract changes seen in RPC.
- Primary sclerosing cholangitis: Can also cause biliary tract strictures and dilatation, but typically lacks the stone formation seen in RPC and is often associated with inflammatory bowel disease.
- Cholangiocarcinoma: May present with similar clinical features but typically demonstrates a mass lesion on imaging.
Management
- The management of RPC involves treating acute episodes of cholangitis, typically with antibiotics, and addressing the underlying causes of biliary tract obstruction.
- Endoscopic retrograde cholangiopancreatography (ERCP) may be used to remove stones and relieve strictures.
- In severe or refractory cases, surgical intervention may be required, potentially including liver resection or even liver transplantation.
- Addressing liver fluke infestations is also key, usually with antiparasitic medications.
- Long-term follow-up is important due to the increased risk of cholangiocarcinoma in these patients.