Treatment outcomes of the interstitial lung disease subtype of unclassifiable type Mycobacterium avium complex pulmonary disease

We aimed to investigate treatment outcomes according to the presence or absence of cavitary lesions in patients with the interstitial lung disease (ILD) subtype of unclassifiable type Mycobacterium avium complex (MAC) pulmonary disease (PD).Study subjects were enrolled at a tertiary referral center in South Korea from 2001 to 2020. Among patients with MAC-PD who had ILD as an underlying disease, 38 patients who were diagnosed with the ILD subtype of unclassifiable MAC-PD and who received treatment for ≥1 year were selected for this study. Treatment outcomes in terms of microbiological cure at 1 year were retrospectively analyzed for these patients.The mean age of the patients was 64.4 ± 12.9 years, and 63.2% were male. The presence of cavitary lesions was noted in 68.4% (26/38) patients. A usual interstitial pneumonia pattern was the predominant type of ILD, which was identified in 26 (68.4%) patients. The overall 1-year microbiological cure rate of the 38 patients was 65.8% (25/38). Of the 26 patients with cavitary lesions, microbiological cure at 1 year was achieved in 14 patients (53.8%), which is significantly lower than that in patients without cavitary lesions (91.7%, 11/12, p = 0.030).A clear difference in treatment outcomes was noted in the ILD subtype of MAC-PD according to the presence or absence of cavitary lesions.