Clinical study of mycobacterium avium complex pulmonary disease complicated by interstitial pneumonia

Background/Aims: We have encountered patients with mycobacterium avium complex (MAC) complicated by interstitial pneumonia (IP) and have had the following questions: 1) Does IP induce MAC as a baseline disease? and, 2) Does steroid therapy for IP cause deterioration of MAC? Methods: We retrospectively examined the medical records of patients with MAC and/or with IP who consulted at the department of respiratory medicine, Himeji Medical Center, Japan between January 2000 and December 2008, and investigated their clinical course based on chest radiography and CT images. Results: Of 29,799 patients who consulted at our department in this period, 346 cases were patients with MAC, 1544 cases had IP, and 18 patients had both MAC and IP. There was no significant difference in the prevalence of MAC between IP patients and IP-free patients (0.0115 vs. 0.0116, p=0.797, chi 2 test). Among 18 patients with both MAC and IP, no difference was seen in the response rate to anti-MAC medication between the steroid-treated group (4/4 cases) and the non-treated group (3/3 cases). Among the patients not receiving anti-MAC medications, little difference was seen in the clinical course of MAC between the steroid-treated group (n=7) and non-treated group (n=4). Conclusions: IP did not significantly increase the prevalence of MAC. No apparent difference was seen in the clinical course of MAC whether or not steroid was administered for IP.