Mycobacterium avium complex (MAC) infection

Presentation

Pleuritic right chest pain, worsening exertional dyspnoea. Past history of MAC infection.

Patient Data

Age: 65
Gender: Female

Multiple areas of airspace opacities with some confluence foci suspicious for mass lesions on the right as well as right apical changes. 

CT

CT Chest

The pulmonary arteries opacify normally without filling defects to a subsegmental level. There has been progression of the bilateral lung scarring, consolidation and bronchiectasis. There is increased cavitation primarily in the right apical region. Some of the opacity within the left lung is ground glass in appearance. Mediastinal lymph nodes are prominent in number but not size. No pleural effusion. Within the limitations of this study, the visualised upper abdominal viscera are unremarkable.No destructive osseous lesion.

Conclusion

No pulmonary emboli detected. There has been progression of the bilateral lung scarring, consolidation, cavitation and bronchiectasis consistent with history of MAC infection.

Sputum sample

MICROSCOPY:
Auramine-Rhodamine Stain:             +++ (> 10 Acid fast bacilli DETECTED per HPF).
Ziehl-Neelsen Stain:                           +++ (> 10 Acid fast bacilli DETECTED per HPF).

ANTIGEN TESTING (ON ISOLATE).
MPT64 Antigen Identification Test: M.tuberculosis Complex NOT detected.

NUCLEIC ACID TESTING (ON SPECIMEN):
M.tuberculosis Complex PCR by GeneXpert: NOT Detected.

MYCOBACTERIUM CULTURE SCREEN:
MGIT bottle (2 days): POSITIVE.

MYCOBACTERIAL CULTURE:
1.Mycobacterium avium Complex           ISOLATED

Case Discussion

Changes in the right upper lobe are those of old TB with no evidence to suggest reactivation. The significant finding is the multiple lung nodules, some cavitating, with some bronchiectasis. These findings alone do not conclusively prove MAC, however in an elderly patient with the appropriate clinical presentation, (e.g. SOB over months, fevers and usually weight loss) then a radiologist can be confident that the diagnosis is MAC. 

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Case information

rID: 21866
Case created: 23rd Feb 2013
Last edited: 24th Jan 2016
System: Chest
Inclusion in quiz mode: Included

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