Teaching Case

A 20-year-old male patient with autoimmune hepatitis presented with worsening jaundice and pruritus. A MRCP was performed, which was compared with the previous 7-month-old MRCP scan. Lab parameters revealed elevated anti-nuclear antibodies along with raised s. bilirubin (8mg/dl) and ALP 305 IU/L.

MRCP performed 7 months before (Fig. 1) revealed normal appearing central intrahepatic biliary radicles (IHBR) and the extrahepatic biliary tree. Very subtle suspicious beading of the peripheral duct can be seen. Follow-up MRCP, seven months later, revealed obvious peripheral bile duct dilatation giving a beaded appearance (Fig. 2, 3). There was associated stricture near the ostium of the right posterior sectoral duct with upstream ductal dilatation.

Based on the imaging findings, and in the light of clinical details, a diagnosis of autoimmune hepatitis / sclerosing cholangitis overlap syndrome was made, which was confirmed histologically.

The three major autoimmune disorders of the liver include autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Overlap syndrome is a term used for overlapping features of autoimmune hepatitis and primary sclerosing cholangitis, or primary biliary cirrhosis and autoimmune hepatitis [1-7].

Autoimmune hepatitis is a chronic immune mediated liver disease, characterised by continuing hepatocellular inflammation and necrosis that tends to progress to cirrhosis. The disease often manifests clinically as chronic hepatitis and is frequently associated with other autoimmune disorders. Diagnosis of AIH is based on immunological assays and histopathological findings. AIH is characterised by the presence of elevated immune markers such as anti-nuclear antibodies (ANA), anti-smooth muscle antibodies (SMA), anti-liver kidney microsome (LKM1) and/ or anti-liver cytosol autoantibodies (LC1), and increased immunoglobulin-G (IgG) levels. Histopathological finding suggestive of AIH include interface hepatitis with massive portal infiltration.

Primary sclerosing cholangitis (PSC) is characterised by progressive inflammation and scarring of the bile ducts manifesting clinically as recurrent episodes of cholangitis. PSC is typically seen in adults but can also affect children. The diagnosis is based on a combination of clinical features and cholestatic biochemical profile, along with typical ERCP/ MRCP findings (beading and stenosis of the intra-and extrahepatic bile ducts), and confirmed by histological findings of periductal concentric fibrosis. Patients with PSC should be suspected of having associated AIH or AIH/PSC overlap syndrome if they have interface hepatitis on biopsy, high serum IgG levels and lower alkaline phosphatase (ALP). It is important to identify these patients as they may be responsive to corticosteroids treatment [7].

Patients with AIH should be suspected of having associated PSC or AIH-PSC overlap if they have pruritis, ulcerative colitis, bile duct abnormalities on histology, cholestatic liver biochemistry (raised ALP) and abnormal cholangiography. These patients tend to be unresponsive to steroids [7]. Follow-up magnetic resonance cholangio-pancreatography (MRCP) performed in the present patient who was diagnosed to have autoimmune hepatitis (with previous grossly normal MRCP) revealed areas of peripheral duct dilatation, irregularity of the peripheral ducts, and dilatation of right posterior sectoral duct with stricturing at its ostium. These MR findings suggested the evolution of PSC. A diagnosis of AIH/PSC overlap syndrome was made based on the concomitant occurrence of clinical, biochemical, serological and histological features of AIH and PSC, as described in the literature [4].