A 48-year-old farmer presents with progressive weight loss, arthralgia, chronic cough, and intermittent diarrhea for two years. Examination shows low-grade fever and generalized lymphadenopathy. Duodenal biopsy shows villi expanded by macrophages that are strongly periodic acid-Schiff positive and diastase resistant. Which organism is responsible?
- A Mycobacterium avium complex
- B Tropheryma whipplei ✓
- C Cryptosporidium parvum
- D Histoplasma capsulatum
Correct answer: B. Tropheryma whipplei
Explanation
Whipple disease is caused by Tropheryma whipplei, an actinomycete. The hallmark is foamy macrophages packed with PAS-positive, diastase-resistant bacilli in the lamina propria, producing blunted villi. Systemic features include migratory arthritis, cough, lymphadenopathy, and later CNS and cardiac involvement. Mycobacterium avium complex in AIDS also gives PAS-positive macrophages, but the bacilli are acid-fast, which distinguishes it from T. whipplei.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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