2 Sep Cavitary Lung Disease

This AM covered a case of long-standing progressive cavitary lung disease, due in this case to Mycobacterium avium.  Cavitary diseases of the lung cover a broad range of infectious and non-infectious causes.  Chronicity of the process, associated findings, and epidemiologic history are all necessary to narrow down the possibilities.  If spontaneous sputum does not reveal the offending pathogen invasive diagnostics are often needed, usually starting with bronchoscopy, followed by CT guided needle biopsy, and ultimately VATS / open lung biopsy.

When you see cavitary lesions on XRay always consider TB, and err on the side of placing the patient in respiratory isolation precautions if you are ordering AFB smears.  Don't wait until they are positive.

Further reading:

Clin Micro Review April 2008 - best review of the differential of cavitary lung lesions with many good images of representative radiographs for many possible causes.

This image from that article shows a MAI cavity very similar to that seen in our patient.

Treatment of non-TB mycobacterial lung disease is actually more complicated than treating TB itself, and takes longer to achieve cure.  These guidelines from the ATS and IDSA cover the topic in depth.