Microscopic features used for the diagnosis of Crohn’s disease
| Colon | |
| Architecture | |
| Crypt architectural irregularity: | Focal |
| Diffuse | |
| Reduced crypt numbers/mucosal atrophy | |
| Irregular surface | |
| Chronic inflammation | |
| Distribution I | Focal increase in intensity |
| Patchy increase | |
| Diffuse increase | |
| Distribution II | Superficial |
| Transmucosal | |
| Basal plasma cells | |
| Granulomas | |
| Mucin granulomas | |
| Polymorph inflammation | |
| Lamina propria | |
| Crypt epithelial polymorphs | |
| Focal | |
| Diffuse | |
| Crypt abscess | |
| Polymorph exudates | |
| Epithelial changes | |
| Erosion/ulceration | |
| Mucin | Depletion |
| Preservation | |
| Paneth cells distal to hepatic flexure | |
| Epithelial associated changes | |
| Increased intraepithelial lymphocytes >15 | |
| Terminal ileum | |
| Architecture | |
| Villus irregularity | |
| Crypt architecture irregularity | |
| Epithelial changes | |
| Pseudopyloric gland metaplasia (ulcer associated cell lineage (UACL)) | |
| Comparison between different segments | |
| Distribution of inflammation along the colon: gradient from proximal to distal | |
| Ratio of number of biopsies with focal cell infiltration to number of biopsies with mononuclear cell infiltration |