Lymphocytic colitis is diagnosed by correlating clinical and histologic findings.


Specimen: random biopsies from grossly normal colonic mucosa


Histologic features of lymphocytic colitis:

(1) lymphocytes within the epithelial cell layer along the surface and within the crypts

(2) degenerative changes in the epithelial cells (flattening, drop-out, etc)

(3) increase in inflammatory cells in the lamina propria consisting mostly of mononuclear cells


intraepithelial lymphocyte count =

= number of intraepithelial lymphocytes per 100 enterocytes


Confidence in the diagnosis of lymphocytic colitis correlates with the number of intraepithelial lymphocytes. Olesen et al required >= 20 lymphocytes per 100 surface epithelial cells for the diagnosis, but other authors accept smaller numbers ("paucicellular").


Things that are absent:

(1) absence of marked distortion in crypt architecture (crypts normal or mildly distorted)

(2) absence of a thickened subepithelial collagen layer (layer < 10 microns thick)

(3) absence of mucosal erosions, crypt abscesses and inflammatory pseudomembranes


To read more or access our algorithms and calculators, please log in or register.