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11 November 2011 Case of the Week #223
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Case of the Week #223
A 55 year old HIV+ man presented with diarrhea and weight loss for one month. He had mildly elevated liver enzymes. Ultrasound showed a granular and enlarged liver, which was biopsied.
What is your diagnosis?
Mycobacterium avium complex (MAC)
Ziehl Neelsen stain
The biopsies showed numerous small aggregates of foamy macrophages distended by dense clusters of rod like structures, highlighted by the Zeehl Neelsen stain.
Mycobacterium avium complex causes disseminated disease in HIV patients (J Infect Dis 1999;179 Suppl 3:S461). Mycobacterium organisms are commonly found worldwide in soil, water, animals, birds and food. Ingested organisms penetrate the GI mucosa, and are phagocytosed by lamina propria macrophages, which are unable to kill them. The bacteria then enter submucosal lymphatics, are transported to abdominal lymph nodes, and enter the bloodstream. In immunocompromised patients, they are disseminated widely, including to liver, spleen and bone marrow. Acid fast stains are recommended for liver biopsies in HIV+ patients (Suriawinata: Liver Pathology, 2011). Fungal stains help rule out co-infections.
Treatment consists of multidrug regiments, such as Clarithromycin 500 mg BID plus ethambutol 15 mg/kg once daily (AIDS Education & Training Centers National Resource Center). Patients should also be started on antiretroviral therapy (ART).
In patients with subclinical or incompletely treated MAC who have recently started ART, an immune reconstitution inflammatory syndrome (IRIS) may occur with localized lymphadenitis or paradoxically worsening symptoms (Int J STD AIDS 2009;20:221).
Nat Pernick, M.D., President
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