S2790 Mycobacterium avium Complex Enteritis Mimicking Whipple's Disease in a Patient With Advanced AIDS

Abstract

INTRODUCTION: Acquired Immunodeficiency Syndrome (AIDS) patients are susceptible to numerous opportunistic infections, including Mycobacterium avium complex (MAC). MAC infection usually presents as a disseminated disease with fever, nights sweats, diarrhea as well as lymphadenopathy which can be the presenting symptoms of various other diseases, such as Whipple's disease (WD). We present a case of MAC infection initially diagnosed as Whipple’s Disease in a patient resulting in delay in MAC treatment. CASE DESCRIPTION/METHODS: A 37 year old homosexual male presented with a one year history of progressively worsening abdominal pain accompanied by intermittent non bloody, non bilious vomiting, chronic diarrhea, fatigue and 60 lbs unintentional weight loss over several months. He underwent an elective EGD where abnormal appearing duodenal mucosa was seen with duodenal biopsy showing villous atrophy and period acid Schiff (PAS) stain positive macrophages, while abdominal imaging showed retroperitoneal and mesenteric lymphadenopathy (Image 1). Despite initiation on treatment for WD, he continued to clinically decline. Given his high risk social history and significant constitutional symptoms, HIV infection was considered as an alternative diagnosis. He was found to have HIV/AIDS (viral load of >100,000 copies/mL and CD4 count 9/μL) and blood cultures positive for MAC. On further review, his duodenal biopsies were positive for acid fast bacillus (AFB) confirming MAC enteritis. A CT chest revealed a 4.6 cm right lung mass with biopsy positive for AFB stain(Image 2). Patient was then initiated on appropriate treatment for disseminated MAC infection (azithromycin, rifabutin, ethambutol) as well as antiretroviral therapy resulting in clinical improvement. DISCUSSION: The differential diagnoses for villous atrophy include malabsorptive diseases, infections, malignancy, pancreatic insufficiency but other less common infectious entities such as MAC should be considered in the right clinical settings. MAC infections have become increasingly uncommon since the advent of highly effective antiretroviral therapy, control of HIV infection and appropriate antimicrobial prophylaxis. Due to the relative rarity, diagnosis and treatment may be delayed, especially when presenting symptoms are non-specific, which can result in morbidity and mortality.Figure 1.: View of duodenum during endoscopy which shows white color plaques in the second and third part of the duodenum (A). H&E stain (20X) of duodenal biopsy shows mildly blunted villi due to expansion of lamina propria by foamy macrophages in a patchy fashion (B). No fat vacuoles or increased intraepithelial lymphocytes seen. AFB stain (20X) of duodenal biopsy shows many positive bacillary forms confirming the presence of Mycobacterium avium intracellular complex (C). Abdominal lymphadenopathy noted on computed tomography of abdomen (red circle) (D).Figure 2.: Computed Tomography of Lung mass (red circle) (A). H&E stain (40X) lung mass biopsy shows florid lympho-histiocytic reaction (B) while CD68 stain (40X) shows many macrophages (C), and AFB stain (40X) confirms presence of mycobacterial organisms (D).