Fig 1A
Fig 1B
Fig 1C
Fig 1A
Fig 1B
Click on Images for Enlarged View
Findings: There is extensive consolidation with cavitation in the left upper lobe.(Fig 1a) There is obstruction of the apical segment bronchus of the left upper lobe. (Fig 1b) Thin walled, lucent cavities are identified within the right upper lobe. (Fig 1c)
Diagnosis: Mycobacterium avium complex infection, with post PCP pneumatocoeles. Bronchoscopy revealed occlusion of the apical segment bronchus by "fleshy" soft tissue. Biopsy revealed extensive inflammatory disease with multiple caseating granulomas c/w MAC infection.
Discussion: Atypical mycobacterial infection has become increasingly recognized as an important respiratory pathogen. In some populations, non tuberculous mycobacterial infection (NMTB) has surpassed TB in incidence. There are several major populations who acquire NMTB and particularly MAC infection. One group has evidence of chronic disease, COPD, alcoholism, and cancer. The second population, as witnessed in this patient, has evidence of immunodeficiency, and AIDS is an important predisposing factor in MAC disease. There is increasing recognition of a third population of immunocompetent, older female patients who develop cough and chronic sputum production who have culture proven MAC disease.
Radiographically, MAC disease can mimic tuberculosis, with consolidation and cavitation. This form tends to occur in more immunocompromised patients. The more indolent form of the disease may show very subtle radiographic disease, with evidence of small nodules and bronchiectasis classically in the right middle lobe and lingula.
While treatment of MAC disease has traditionally required long, multidrug therapy, the recent use of antibiotics such as clarithromycin has simplified the treatment of this increasingly important pathogen.
References:
Prince DS, et al. Infection with Mycobacterium Avium Complex
in Patients Without Predisposing Conditions. NEngl J Med 1989; 21:863-868.
Miller WT Jr. Spectrum of Pulmonary Nontuberculous
Mycobacterial Infection. Radiology 1994; 191:343-350.
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