Contrasting Pattern of Chronic Inflammatory Bowel Disease in Primary and Autoimmune Sclerosing Cholangitis.

Background: Primary sclerosing cholangitis (PSC) and autoimmune sclerosing cholangitis (AISC) are related, but distinct chronic liver diseases. PSC is associated with a high prevalence of ulcerative colitis while the intestinal inflammation associated with AISC is less well characterised.
Aims: To assess and contrast aspects of intestinal inflammation in patients with AISC and PSC and compare the clinical features with those of patients with ulcerative colitis and Crohn's disease.
Methods: 23 and 22 patients with AISC and PSC, respectively, underwent review of colonoscopy and biopsy findings, capsule enteroscopy and assessment of clinical and inflammatory (faecal calprotectin) disease activity, which was compared with that of patients with ulcerative colitis and Crohn's disease (n = 55 each).
Findings: Five and 6 patients with AISC and PSC, respectively, had normal colonoscopy and faecal calprotectin levels of 34.4 ± 8.3 and 39.7 ± 8.4 μg/g, respectively (normal < 50 μg/g), whereas 18 and 16, respectively, had identical variably severe, right sided colitis with frequent rectal sparing, consistent with ulcerative colitis. Mean (± SD) faecal calprotectin levels did not differ significantly (p > 0.05) between patients with intestinal inflammation in AISC (588 ± 549 μg/g), PSC (421 ± 351 μg/g), ulcerative colitis (501 ± 656 μg/g) or Crohn's disease (476 ± 571 μg/g). Capsule enteroscopy showed that 7 of 18 (39%) (p < 0.03) of those with AISC had small bowel mucosal breaks whereas no patient with PSC had these findings.
Interpretation: Collectively these findings lend support to the suggestion that the chronic inflammatory bowel disease associated with PSC and in particular AISC may represent a distinct nosologic entity different from classic ulcerative colitis and Crohn's disease.