HIV Infection and Worsening Diarrhea: What's Your Dx?

Mycobacterium avium complex enteritis; cytomegalovirus; Whipple disease; sprue: what endoscopic findings reveal the cause of worsening diarrhea in this HIV-infected man with a CD4 cell count of 32/μL?

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
b. Cytomegalovirus
c. Whipple disease
d. Tropical sprue

 Please click here for the answer and discussion.

Mycobacterium avium complex (MAC) enteritis can affect patients with HIV infection-particularly those with a low CD4 cell count (< 50/µL). Both MAC and Whipple disease may reveal foamy macrophages on biopsies and both are PAS-positive; however, only MAC would also demonstrate acid-fast macrophage inclusions.