Disseminated Mycobacterium avium-intracellulare Infection Presenting as Multiple Ring-Enhancing Lesions on Brain MRI

Abstract

A 33-year-old man in whom AIDS had been diagnosed in 2003 presented with a 6-week history of progressive generalized weakness, lethargy, dysphagia, slowing of speech, and left-sided weakness. Highly active antiretroviral therapy was initiated, but the patient was not adherent to this regimen. Disseminated Mycobacterium avium-intracellulare infection in the lungs and supraclavicular lymph nodes had been diagnosed 3 to 4 weeks before presentation. Magnetic resonance imaging (MRI) of the brain revealed multiple ring-enhancing lesions. A presumptive diagnosis of central nervous system toxoplasmosis was made, and an extensive work-up for ruling out other causes of multiple ring-enhancing lesions was initiated. Laboratory studies yielded a serum CD4 cell count of 2/μL and a human immunodeficiency virus RNA count of 6100 copies/μL. Results of the following were negative: serum cryptococcal antigen, Bartonella henselae IgM and IgG, cytomegalovirus antigen, rapid plasma reagin, and Toxoplasma IgM and IgG. The following cerebrospinal fluid (CSF) results were negative: Toxoplasma IgM, IgG, Toxoplasma by polymerase chain reaction and staining, acid-fast bacilli (AFB) stain, cryptococcal antigen, venereal disease research laboratory test, Gram stain, and bacterial and fungal cultures. Cytologic examination of the CSF showed numerous neutrophils but no malignant cells. Laboratory studies of the CSF yielded a protein value of 52 mg/dL (to convert to mg/L, multiply by 10) (reference range, 15-45 mg/dL) and a glucose value of 26 mg/dL (to convert to mmol/L, multiply by 0.0555) (reference range, 40-70 mg/dL); the CSF was clear, colorless with 5 red blood cells and 42 white blood cells (77% polymorphonuclear and 23% mononuclear cells). Brain biopsy with AFB stain revealed 3+ AFB (M avium) but showed no Nocardia-like organisms. A modified Kinyoun stain for Nocardia species was negative, as was a wetmount preparation for amebae. A liquid-based biopsy culture grew M avium after 10 days of incubation. A confirmatory DNA probe was performed to verify the diagnosis of central nervous system toxoplasmosis. Therapy with ethambutol, rifampin, and amikacin was initiated; however, the patient chose palliative care after talking with his family.