Normal

• parts
  • duodenum
    • Brunner glands
  • ampulla
    • ampullary epithelium
      • simple columnar
      • scattered goblet cells
    • accessory pancreatic ducts and acini
    • pancreatic duct
    • common bile duct
    • sphincter of Oddi
  • jejunum
  • ileum
    • Peyer patches
  • ileocecal valve
    • can contain mass forming adipose tissue
• layers
  • mucosa
    • epithelium
      • villi and crypts
      • brush border
      • goblet cells
      • paneth cells
      • endocrine cells
      • intraepithelial lymphocytes
      • lacteals
    • lamina propria
  • muscularis mucosa
  • submucosa
    • Submucosal plexus
    • Brunner glands
    • Peyer patches
  • muscularis propria
    • circular layer
    • Myenteric plexus
    • longitudinal layer
  • subserosa
• Signout
  • Benign enteric mucosa
  • No dysplasia, enteritis or villous abnormalities identified

Approach

• epithelial abnormalities
  • dysplasia: HG present? vs reactive
  • carcinoma
  • foveolar metaplasia
• stromal infiltrate
  • soft tissue tumor
  • hematolymphoid
• enteritis
• villous abnormalities
• clinical cues
  • IBD: enteritis, dysplasia, foveolar metaplasia, granuloma, CMV effect
  • diarrhea: enteritis, villous blunting
  • polyp: adenoma, lymphoid nodule, inflammatory polyp, neuroendocrine

polyp

enteritis

Other

• hyperplasia
  • lymphoid hyperplasia
  • brunner gland hyperplasia
• metaplasia
  • foveolar metaplasia
• heterotopia
  • gastric heterotopia
  • pancreatic heterotopia
  • paraduodenal pancreatitis
• injury
  • peptic duodenitis
  • peptic ulcer
  • NSAID effect
  • treatment effect
  • NEC
  • perforation
• malabsorption
  • celiac disease
  • tropical sprue
  • Whipple disease
  • bacterial overgrowth
  • protein intolerance
• nutrition deficiency
  • B12 deficiency
  • protein deficiency
  • zinc deficiency
  • iron deficiency
• ischemic enteritis
• GVHD
• Hirschsprung disease
• Ostomy
• Fistula
• Meckel diverticulum
• other
  • dilated lymphatics
  • microvillous inclusion disease
  • lymphangiectasia
  • paneth cell hyperplasia
  • gastric foveolar metaplasia
  • lipid hang-up
  • colchicine effect
  • endometriosis
  • pneumatosis cystoides intestinalis
  • Waldenstrom macroglobulinemia

neoplasm

Grading

• well differentiated: > 95% glands
• moderately differentiated: 50-95% glands
• poorly differentiated: 5-50% glands
• undifferentiated: < 5% glands
• poorly differentiated by definition: mucinous adenocarcinoma and signet ring cell carcinoma

TNM (useful for grossing)

• carcinoma
  • Tis: in situ (small intestine)
  • T1: submucosa confined
    • T1a: lamina propria or muscularis mucosae
    • T1b: submucosa
  • T2: into muscularis propria
  • T3: subserosa invasion or <= 2cm mesentery extension
  • T4: serosa perforation or adjacent structure invasion (other loops of bowel, mesentery, etc)
  • N1: 1-3 nodes
  • N2: 4+ nodes
• carcinoid
  • T1: size <= 1 cm and submucosa confined
  • T2: size > 1 cm or muscularis invasion
  • T3
    • jejunal or ileal: subserosa invasion
    • ampullary or duodenal: pancreas or retroperitoneum invasion
  • T4: perforates serosa or adjacent structure invasion
• ampullary tumor
  • Tis: in situ
  • T1: limited to ampulla of Vater or sphincter of Oddi
  • T2: duodenal wall invasion
  • T3: pancreas invasion
  • T4: peripancreatic soft tissue or adjacent structure invasion

Staging

• carcinoma
  • 0: Tis
  • I: T1-2
  • IIA: T3
  • IIB: T4
  • IIIA: N1
  • IIIB: N2
  • IV: M1
• carcinoid
  • I: T1
  • IIA: T2
  • IIB: T3
  • IIIA: T4
  • IIIB: N1
  • IV: M1
• ampullary tumor
  • 0: Tis
  • IA: T1
  • IB: T2
  • IIA: T3
  • IIB: N1
  • III: T4
  • IV: M1