Stomach
Peptic ulcer disease, gastric malignancies (adenocarcinoma, GIST, MALT/lymphoma), and post-gastrectomy syndromes for the Surgery Shelf.
Sources: extracted/STEP2CK-Surgery.md (Stomach); First Aid 2026 (first-aid-usmle-bible).
High-Yield Points
- Parietal cells (fundus/body) secrete H⁺ and intrinsic factor; stimulated by ACh, gastrin, histamine (final common pathway = H⁺/K⁺ ATPase, blocked by PPI). G cells (antrum) secrete gastrin; D cells secrete somatostatin (inhibits gastrin/acid).
- Peptic ulcer disease: #1 cause is H. pylori; next NSAIDs and smoking. Duodenal ulcers (younger, more common) — pain relieved by food, recurs ~30 min later; anterior → perforate, posterior → bleed (gastroduodenal artery). Gastric ulcers (older) — higher cancer risk, so biopsy them; 80% on lesser curvature.
- PUD Tx: triple therapy (PPI + amoxicillin + clarithromycin); confirm eradication with urea breath test. Bleeding ulcer → EGD first (clips/epi/cautery); surgery = GDA ligation (duodenal) / resection (gastric).
- Surgical PUD indications: perforation, bleeding refractory to EGD, obstruction, intractability, can't exclude cancer. If on PPI → add acid-reducing surgery. Perforated duodenal ulcer → Graham (omental) patch.
- Zollinger-Ellison (gastrinoma): refractory/distal ulcers + secretory diarrhea + high gastrin; secretin stimulation test (paradoxical rise) confirms, octreotide scan localizes. 80% in Passaro triangle. Associated with MEN1 (gastrinoma = most common functional pancreatic NET in MEN1; insulinoma most common overall).
- Gastric adenocarcinoma (90% of gastric cancers): #1 risk = H. pylori. Intestinal type (glands, elderly males, Japan) vs diffuse type / linitis plastica (signet-ring, women, worse prognosis → total gastrectomy). Need ≥15 nodes, ≥5 cm margin; EUS best for T/N depth, CT for distant mets. Hereditary diffuse gastric cancer = CDH1.
- GIST: most common mesenchymal tumor; interstitial cells of Cajal, c-kit (CD117)+. Malignancy by size >5 cm and mitoses >5/50 HPF. Tx: resection with 1-cm margins (no nodal dissection — hematogenous spread); imatinib if high-risk.
- MALT lymphoma: driven by H. pylori — first treat the infection (regresses in ~80%); t(11;18) won't respond.
Key Tables / Differentials
Duodenal vs gastric ulcer
| Duodenal | Gastric | |
|---|---|---|
| Age | Younger (30–50) | Older (>60) |
| Acid | High | Normal/low (↓ mucosal protection) |
| Food | Pain relieved by eating | Pain worsened/recurs with eating |
| Cancer risk | Negligible | Significant → biopsy |
| Bleeding source | Posterior → GDA | Lesser curvature |
Gastric metastasis eponyms
| Eponym | Site |
|---|---|
| Virchow node | Left supraclavicular |
| Krukenberg tumor | Ovary (signet-ring) |
| Sister Mary Joseph node | Periumbilical |
| Blumer shelf | Rectal shelf (pouch of Douglas) |
| Irish node | Left axillary |
Stress ulcers
| Eponym | Setting | Site |
|---|---|---|
| Cushing ulcer | Traumatic brain injury (↑ICP) | Gastric |
| Curling ulcer | Burns | Duodenal |
Board Pearls
- Pinpoint mucosal defect, brisk bleed, lesser curve, normal-looking mucosa = Dieulafoy lesion → endoscopic therapy.
- Elderly/cirrhotic with chronic GI bleed, "watermelon stomach" = gastric antral vascular ectasia (GAVE).
- Sudden epigastric pain + retching without vomiting + can't pass NG tube = Borchardt triad → gastric volvulus (surgical emergency).
- Giant rugal folds + protein loss + ↑TGF-α = Ménétrier disease.
- Hypochloremic, hypokalemic metabolic alkalosis + succussion splash = gastric outlet obstruction.
- Diarrhea is the most common complication after vagotomy.
Classic Vignette Triggers
- "Epigastric pain relieved by food, recurs at night" → duodenal ulcer (H. pylori).
- "Recurrent ulcers despite PPI + diarrhea + high gastrin" → ZES/gastrinoma (secretin test, think MEN1).
- "Submucosal gastric mass, c-kit/CD117 positive" → GIST → resect, imatinib if high-risk.
- "Gastric ulcer with H. pylori MALToma" → eradicate H. pylori first.
- "Linitis plastica / signet-ring cells, woman" → diffuse gastric cancer → total gastrectomy.
- "Post-gastrectomy: sweating, palpitations, diarrhea 20 min after eating" → early dumping syndrome (small high-protein meals; octreotide if refractory).