A 50-year-old man presents with chronic diarrhoea, steatorrhoea, and weight loss of 10 kg over 8 months. He also has migratory polyarthralgias and intermittent low-grade fever. Examination reveals hyperpigmented skin and mild generalized lymphadenopathy. Duodenal biopsy shows lamina propria distended by PAS-positive, diastase-resistant macrophages. Which organism is responsible?
- A Mycobacterium avium complex
- B Giardia lamblia
- C Tropheryma whipplei ✓
- D Histoplasma capsulatum
Correct answer: C. Tropheryma whipplei
Explanation
Whipple disease is caused by Tropheryma whipplei, a gram-positive actinobacterium. The classic presentation includes malabsorption, arthralgias, weight loss, and hyperpigmentation. PAS-positive macrophages in the lamina propria are pathognomonic, containing diastase-resistant granules of bacilli and their glycoprotein debris. Mycobacterium avium complex produces similar PAS-positive macrophages but in immunocompromised hosts. Giardia shows trophozoites on biopsy, and Histoplasma is a dimorphic fungus endemic to specific regions.
Reference: Harrison's Principles of Internal Medicine, 20th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.