The subepithelial band in collagenous colitis is autofluorescent a study in H&E stained sections

The normal basement membrane (BM) of the colon and the collagenous colitis band (CCB) seen in H&E-stained sections were recently found to be autofluorescent. Measurements of the thickness of the BM and of the CCB were taken using transmitted-light (TL) and incident-light fluorescence (IFL). The mean thickness of the BM in control cases was 3.2 microns with TL and 3.4 microns with IFL. The mean thickness of the CCB was 50.3 microns with TL and 55.8 microns with IFL. In 10 consecutive cases of CC, the thickness of the CCB was repeatedly measured in the same area, on different occasions. Substantial variations in the vertical size of the CCB were recorded in the same area when using TL but not with IFL. Good demarcation of the CCB with ILF and poor demarcation of the deep border of the hyaline band, because of overlapping inflammatory cells, were the apparent causes. Autofluorescence was induced by the eosin stain. The results suggest that the simple observation of H&E--stained biopsies with ILF may be sufficient to diagnose CC. Re-sectioning for special staining can be avoided, thus reducing final diagnosis-time and laboratory costs.