A 58-year-old man presents with weight loss, arthralgia, chronic diarrhoea and low-grade fever. Duodenal biopsy shows villi distended with macrophages containing periodic acid-Schiff positive, diastase-resistant granules. Which organism is responsible?
- A Mycobacterium avium complex
- B Histoplasma capsulatum
- C Tropheryma whipplei ✓
- D Cryptosporidium parvum
Correct answer: C. Tropheryma whipplei
Explanation
Whipple disease is caused by Tropheryma whipplei, an actinomycete. The hallmark is foamy macrophages packed with PAS positive, diastase resistant bacilli within the lamina propria, producing villous blunting and lymphatic obstruction. Mycobacterium avium complex in AIDS also gives PAS positive macrophages, but the organisms are acid fast on Ziehl-Neelsen stain, whereas T. whipplei is acid fast negative, which is the discriminating fact.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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