[Distribution of pulmonary Mycobacterium avium complex (MAC) disease cavities and their course under chemotherapy]

The presence of a cavitary lesion is important factor for pulmonary Mycobacterium avium complex (MAC) treatment.

Clarify the location of pulmonary MAC cavities and the changes of these cavities.

We observed the location of 56 cavities in 48 patients with pulmonary MAC on computed tomography (CT) images and evaluated the changes in the external diameter of these cavities before and after treatment with a regimen of rifampicin (RFP), ethambutol (EB), and clarithromycin (CAM).

These pulmonary MAC cavities were significantly frequently located in segments S2, S3, S9, and S10, and their distribution was different from that of pulmonary tuberculosis at the patients' initial visit. Examination of the external diameters of these cavities after chemotherapy showed that 42.1% of cavities expanded, 0.2% were unchanged, and 56.1% shrank. The mean diameter of the cavities decreased significantly (by 3.1 mm) after chemotherapy. The mean size of the cavities in the upper lobe did not differ from the mean size of the cavities in the lower lobe before chemotherapy; however, the reduction in cavity size was significantly higher in the lower lobe cavities. In 14 cases, the cavities disappeared under the standard chemotherapy regimen in an average of 971 days, and there was a tendency for lower lobe cavities to disappear more rapidly.