A 54-year-old man with HIV infection presents with increasingly worsening diarrhea. His CD4 cell count is 32/µL. Upper endoscopy with duodenal biopsies is performed. Specimens reveal sheets of foamy macrophages in the lamina propria. Periodic acid–Schiff (PAS) and acid-fast bacillus stains are notable for rod-shaped organisms.
What is the most likely diagnosis?
a. Mycobacterium avium complex
c. Whipple disease
d. Tropical sprue