FIG. 1.

Histological grading scale (grades 1–6) illustrated using representative hematoxylin–eosin-stained sections of colonic mucosa. Grade 1: Intact epithelium and lamina propria. No structural abnormality. Grade 2: Detatched epithelium but intact lamina propria. Chronic inflammatory cell infiltrates. Grade 3: Detached epithelium and disaggregated lamina propria. Neutrophil infiltrates in lamina propria. Grade 4: Detached epithelium and disaggregated lamina propria with >30% karyorrhexis. Neutrophil infiltrates in epithelium. Grade 5: Detached epithelium and disaggregated lamina propria with >75% karyorrhexis and crypt destruction. Grade 6: Epithelium lost and minimal cellular remnants, with mostly structural elements remaining and erosions or ulcerations present. Biopsy samples scored as grade 1 were categorized as normal. Samples scored as grades 2–3 were categorized as having mild changes, grade 4 samples were categorized as moderate, and grades 5–6 were categorized as severe.