Villous blunting

• Celiac disease
• Whipple disease
• other sprue
  • tropical sprue
  • collagenous sprue
  • unclassified sprue
• deficiency (B12, iron, protein)

Crohns

Infectious enteritis

• virus
  • CMV
  • HSV
  • adenovirus
  • HIV
• bacterial overgrowth
• fungi
• parasites

lymphoid hyperplasia

Ulcer/infarct

• peptic ulcer (NSAID, gastric heterotopia)
• ischemia
• CMUSE

Infant

• autoimmune enteropathy
• NEC

Eosinophils

• eosinophilic gastroenteritis
• parasite (stool studies)
• vasculitis (vasculocentric)

Clin hx driven

• GVHD
• mycophenolate
• drug
• radiation enteritis
• pouchitis
• backwash ileitis