Table 1

Definitions of some histological features

FeatureFiguresDefinition/descriptionAdditional commentsReferences
Villiform/irregular mucosal surface2DUndulating or broadly villiform surface. Wide crypt mouthsSeparation of crypts yielding surface contour of broad villus-like projections3 4
Crypt distortion2D–FMay include branching, loss of parallelism, irregularity, tortuosity, dilatation and variation in shape and sizeCaution adjacent to crypt abscesses and lymphoid aggregates/follicles.
Anal transition zone/columnar cuff unsuitable for assessment
3 18 19 25 28 31–33
Crypt branching2E,FTwo or more branched crypts in a well-oriented biopsy. Included in crypt distortionBranching between mucosal hillocks/at innominate grooves is normal11 18 19 25 28 34
Crypt atrophy2DMinimum: crypt shortening, with increased gap between crypt base and muscularis mucosae.
Additional evidence: wider spacing of crypts; >1 crypt diameter between crypts
Caution near lymphoid follicles and near muciphages.
Anal transition zone/columnar cuff unsuitable for assessment.
Intercrypt/subcryptal spaces may be higher in caecum and rectum
1 3 11 18 21 25 28 33
Basal plasmacytosis2GPlasma cells at base of mucosa. May separate crypts from muscularis mucosae but not always subcryptal.
Loss of plasma cell gradient
Basal plasma cells are normal in the caecum and ascending colon3 4 18 28
Basal lymphoid aggregates2HNodular collections of lymphocytes with or without germinal centres. May be between muscularis mucosae and cryptsOne or two transmucosal lymphoid nodules can be seen in normal mucosa; can extend across muscularis mucosae. Pathological aggregate may be difficult to distinguish from normal3 18 19 25
CryptitisNeutrophils in crypt epithelium18 28 31
Crypt abscessNeutrophils in crypt lumenOften located near base of crypt18 28 31 34
Granulomas3ADiscrete collection of at least five epithelioid macrophagesConsider crypt rupture as a cause. Serial sections may help with this11 18 25
Mucin depletion2D,FUnequivocal reduction of goblet cell mucin in crypt epitheliumMucin in normal mucosa may be reduced near lymphoid follicles.
Depletion can reflect bowel preparation
11 19 21 35
Paneth cell metaplasia3BPyramidal crypt epithelial cells with supranuclear eosinophilic granular cytoplasmNormal in caecum and right colon, probably as far as splenic flexure19 25