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* = Presenting author

P268 A questionnaire on the diagnosis of microscopic colitis in Denmark

P. J. H. Engel*1, 2, S. Holck3, U. H. Engel3

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

Background

Microscopic colitis (MC) is a triad of chronic diarrhoea, normal endoscopy, and characteristic histological findings. The histological criteria of MC (collagenous colitis [CC] and lymphocytic colitis [LC]), defined in the 1980s, are based on HE-stained sections, which according to recent European guidelines is sufficient to diagnose MC. Recently, another subset of MC, named incomplete MC (MCi), has been introduced, covering patients with prolonged diarrhoea and normal endoscopy, but with biopsies not fulfilling the histological criteria of MC (ie, biopsies with 5–20 IELs / 100 cells [LCi] or with a subepithelial collagen band measuring 5–10 my [CCi]). The purpose of the questionnaire is to register the gastrointestinal (GI) pathologists’ practice of staining and SNOMED coding colorectal biopsies, with focus on MC/MCi. An additional purpose is to investigate awareness of the MCi subset.

Methods

A questionnaire was mailed to all 15 pathology departments in Denmark, addressed to those consultants responsible for the diagnostics of GI specimens. All 15 departments participated and 48 GI pathologists contributed.

Results

Initial staining was applied to non-neoplastic colorectal biopsies: 71% of respondents use HE only, the remaining use HE combined with a connective tissue staining and/or mucous staining. Colorectal biopsies with histological suspicion of CC 67% use a non-IHC connective tissue staining, and 12% apply the tenascin (IHC staining) in addition to HE staining. Colorectal biopsies with histological suspicion of LC 85% use IHC staining for T-lymphocytes (CD3) in addition to HE staining, and 15% do not apply additional staining. As for awareness of MCi, 50% report consistent use of the term microscopic colitis obs. pro, indicating knowledge the MCi subset. SNOMED codes of MC /MCi, codes for CC / LC are used consistently. Codes for MCi are presently not available, necessitating the use of codes that are less specific.

Conclusion

A 100% response rate was obtained, illustrating the respondents’ interest in this field. Suspicion of MC conspicuously increased the use of special stains/IHC. Considering the recommendations of the European guidelines the wide use of particularly CD3 is noteworthy. Awareness of MCi is widespread; however, to learn more about LC and LCi, we recommend assessment of the utility of CD3 in differentiating LCi from LC and from non-specific colitis, respectively. We also emphasise the need for a SNOMED code for LCi and CCi. Such undertaking could be the pathologists’ contribution to reduce the risk of missing patients with a treatable cause of diarrhoea.