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Lessons from Mycobacterium avium complex-associated pneumonitis: a case report
Victor Zota1, Sheryn M Angelis, Armando E Fraire
1Department of Pathology, Division of Infectious Disease, University of Massachusetts Medical School, Worcester, MA, USA. zotav@ummhc.org
Journal of Medical Case Reports
|May 15, 2008
Summary
Mycobacterium avium complex (MAC) lung disease can occur without hot tub exposure. This case shows MAC-associated pneumonitis involves a strong immune response to infection, suggesting combined anti-infective and anti-inflammatory treatments.
Area of Science:
- Pulmonary Medicine
- Immunology
- Infectious Diseases
Background:
- Mycobacterium avium complex (MAC) is a growing cause of lung disease in immunocompetent individuals.
- MAC-associated pneumonitis, often linked to hot tubs, is debated as hypersensitivity pneumonitis or direct infection.
- This study presents a rare case of MAC-associated pneumonitis unrelated to hot tub use.
Purpose of the Study:
- To describe a unique case of MAC-associated pneumonitis.
- To investigate the immunopathology of MAC-associated pneumonitis.
- To challenge the classification of MAC-associated pneumonitis.
Main Methods:
- Case report of a 52-year-old immunocompetent patient with MAC-associated pneumonitis.
- Identification of Mycobacterium avium complex (MAC) from an intrapulmonary cyst.
- Histological examination of lung tissue, including T-cell and histiocyte analysis and cytokine staining.
Main Results:
- The patient presented with disseminated miliary nodules.
- Histology revealed non-acid-fast granulomas rich in CD4+ T-cells and CD68+ histiocytes.
- Granulomas showed strong positivity for tumor necrosis factor-alpha.
Conclusions:
- Classifying MAC-associated pneumonitis solely as hypersensitivity or direct infection is unhelpful.
- MAC-associated pneumonitis involves a robust T-helper 1-like inflammatory response to mycobacterial infection.
- Combined anti-MAC and anti-inflammatory therapy may be beneficial for treatment.
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