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* = Presenting author

P080 Persistence and sensitivity of colonic biopsies for microscopic colitis in a regional cohort

J. Rasmussen1, P.J.H. Engel2, L.K. Munck*3

1Koege University Hospital, Department of Medicine, Koege, Denmark, 2Roskilde University Hospital, Department of Pathology, Roskilde, Denmark, 3University of Copenhagen, Faculty of Health and Medical Sciences, Copenhagen, Denmark

Background

Microscopic colitis (MC) includes collagenous (CC), lymphocytic (LC) and incomplete microscopic colitis (MCi). The ECCO guideline recommend that a diagnosis of inflammatory bowel disease should be based on separate biopsies from several colonic segments. If applied to patients with chronic diarrhoea this would markedly increase the pathologists' work load.

Persistence of MC

CCLCMCi
Early (≤ 1 year)76% (41/54)58% (18/31)27% (12/45)
Late (> 1 year)61% (46/75)53% (17/32)18% (3/17)

We estimate the sensitivity of left- and right-sided colonic biopsies for the diagnosis of MC and MC subgroups in a non-selected population of patients and identify histological changes before and after the diagnostic endoscopy.

Methods

All consecutive MC patients diagnosed from January 2000 through March 2014 were identified and included. From the Danish National Pathology Database we extracted for each patient the indication, time and type of all endoscopies, number of biopsies obtained, and biopsysegment. The diagnostic criteria were as previously described. Biopsies from the colon oral to the splenic flexure were classified as right sided and biopsies from the sigmoid and descending colon as left sided. Rectal biopsies were excluded.

Results

MC was diagnosed in 749 patients; 354 with CC, 245 with LC and 196 with MCi. The diagnostic procedure was colonoscopy in 221 with CC, 159 with LC and 120 with MCi. The median number of biopsies taken at the diagnostic endoscopy was 7. The sensitivity of biopsies from the left and right colon for the three MC subtypes was 98%-100% and 89%-98%, respectively. 4 patients had histological changes of MC in the right colon only and 17 in the left colon only. Endoscopies prior to the diagnostic endoscopy had been performed in 132 patients a median of 12 (0-218), 5 (1-53) and 16 (1-188) months before the diagnosis of CC, LC and MCi, respectively. The pre-diagnostic histology was normal in 26%, 17% and 22% and chronic inflammation in 40%, 43% and 24% in the three MC subgroups. Post-diagnostic endoscopies were preformed in 129 (37%) with CC, 63 (27%) with LC and 62 (32%) with MCi. The histology was normal in 12%, 10% and 8%. Change to a different MC subgroups occurred in 5%, 11% and 27%. Persistence of MC in the first post-diagnostic endoscopy according to primary diagnosis and time to endoscopy is shown in the table.

Conclusion

The diagnostic sensitivity does not differ between the right and left colon. Chronic inflammation in colonic biopsies from patients with chronic diarrhoea should raise suspicion of MC. The histological findings of CC and LC persist in half of the patients, but rarely normalises. MCi frequently changes to LC or CC.