Diagnosis-crohn’s disease

• Ileocolonoscopy + bx along w/ small bowel assessment (eg, MR-enterography)

• Small bowel/ileitis (~25%), ileocolonic (~50%), colonic (~25%); isolated upper tract rare

• Appearance: nonfriable mucosa, cobblestoning, aphthous ulcers, deep & long fissures

• Histology: transmural inflammation with mononuclear cell infiltrate, noncaseating granulomas (seen in <25% of mucosal biopsies), fibrosis, ulcers, fissures, skip areas

• Montreal classification: age at dx, disease location & behavior (stricturing vs. nonstricturing, penetrating vs. nonpenetrating), plus modifiers for upper tract & perianal disease