Paper II
Question
Causes and morphology of acute and chronic gastric ulcers
Answer
Acute gastric ulcers (acute erosive/stress ulcers)
Causes
- Severe physiological stress — extensive burns (Curling ulcer), raised intracranial pressure/CNS injury (Cushing ulcer, thought to be due to direct vagal stimulation causing gastric hypersecretion)
- NSAID use (inhibits protective prostaglandin synthesis)
- Severe trauma, sepsis, shock (mucosal ischaemia)
- Heavy alcohol consumption
Morphology
- Multiple, small (usually <1 cm), shallow lesions with a brown-black base (due to acid digestion of extravasated blood)
- Can occur anywhere in the stomach
- Microscopically limited to mucosa/superficial submucosa, with minimal surrounding inflammatory reaction (acute onset), surrounded by normal gastric mucosa
Chronic peptic ulcers
Causes
- Helicobacter pylori infection (most common cause)
- NSAID use
- Zollinger-Ellison syndrome (gastrin-secreting tumour causing acid hypersecretion)
- Smoking (impairs healing)
Morphology
- Usually solitary, round to oval, sharply “punched-out” defect, most commonly on the lesser curvature of the antrum or duodenum (first part)
- Sharply demarcated, overhanging margins on the proximal side, with a shelving/terraced distal margin (due to differential peristaltic movement)
- Base is smooth and clean due to peptic digestion, may show visible blood vessels
- Microscopically, four distinct layers are seen at the base: (1) a thin layer of necrotic fibrinoid debris, (2) a zone of nonspecific inflammatory infiltrate (predominantly neutrophils), (3) active granulation tissue, and (4) a fibrous/collagenous scar
- Surrounding mucosa often shows chronic gastritis