Giardiasis

Epidemiology:

• Immunosuppressed at greater risk

Common sites:

• Duodenum and jejunum
• Colon occasionally
• Gallbladder occasionally (immunosuppressed)

Gross features:

Histologic features:

• pear-shaped crescent-shaped discs, binucleated, flagellated
• adhering to or hanging around epithelium (not invading)
• mucosal appearance may be normal, or:
• marked blunting of villi
• mixed inflammatory infiltrate in lamina propria
• irregular brush border

Markers:

• Masson’s trichrome
• Giemsa