Ulcerative Colitis

Common sites:

• Limited to colon

Gross features:

• Extends proximally from rectum
• There is often a cecal patch / kick in the cecum near the appendix that may be involved discontinuously
• Rectum may be spared due to treatment effect (enema treatments)
• Note that terminal ileum may be involved (“backwash ileitis”) in severe pancolitis in distal few centimeters
• Continuous involvement
• Note that patchy areas of healing or rectal sparing may be seen as a result of treatment
• also these features may be seen in pediatric UC patients
• May have extensive and broad-based ulceration with pseudopolyps between
• No mural thickening

Histologic features:

• 3 important and easy diagnostic features for IBD:
• architectural distortion (variation from orderly test-tubes, branching, budding)
• deep plasma cells within chronic inflammatory infiltrate – look at bottom of crypts near muscularis mucosa
• note that deep plasma cells are normal in the cecum and terminal ileum
• Paneth cell metaplasia – shouldn’t see Paneth cells past hepatic flexure
• More severe disease as you go distally
• Note there is often a cecal patch / kick in the cecum near the appendix where disease may be present discontinuously
• Note there may be patchy healing or rectal sparing as a result of treatment
• Note that terminal ileum may be involved (“backwash ileitis”) in severe pancolitis
• First is a diffuse, predominantly mononuclear inflammatory infiltrate in the lamina propria
• Crypt abscesses
• Ulceration up to muscularis propria
• Watch for dysplasia
• Eosinophils stick around between attacks

Immunophenotype:

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Molecular features:

Other features: