An 18-year-old boy who had no significant medical history presented with loose stools and abdominal pain that had lasted more than 8 months. CT examination showed diffuse thickening of the colon (Fig. 1, arrows), as well as irregularity and increased enhancement of the rectosigmoid mucosa (Fig. 1, arrowheads). CT also showed a nodular liver associated with shrunken left hepatic lobe, hypertrophied caudate lobe, intrahepatic biliary ductal dilatation (Fig. 2, arrow) and ascites. The patient underwent a colonoscopy, liver biopsy and biochemical studies. The results were consistent with the overlapping syndrome of autoimmune hepatitis (AIH) and primary sclerosing cholangitis (PSC).

Fig. 1
figure 1

Coronal reconstructed enhanced CT

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Fig. 2
figure 2

Axial enhanced CT

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The etiology of AIH and PSC is not clearly known but is presumed to be autoimmune-related. The overlapping syndromes of AIH and PSC are rare but are typically observed in children and young adults, often resulting in diagnostic and management difficulties [1, 2]. In this patient, overlapping syndromes of AIH and PSC were associated with biopsy-proven ulcerative colitis [2].