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A1986 - Nontuberculous Mycobacterial Lung Disease Secondary to Interstitial Pneumonia
Author Block: S. Hashimoto, E. Tanaka, Y. Hidetaka, U. Masakuni, T. Satoru, T. Nakanishi, H. Nobuyoshi, I. Takashi, K. Yusuke, Y. Takehiro, H. Takashi, T. Yoshio; Respiratory Medicine, Tenri Hospital, Tenri Nara, Japan.
Background: Nontuberculous mycobacterial (NTM) lung disease occurs in patients with structural lung diseases. Little is known about NTM infections secondary to interstitial pneumonia (IP). Objectives: To clarify the prevalence and characteristics of NTM lung disease in patients with IP. Methods: We retrospectively reviewed medical records of 1,367 consecutive IP patients who visited our hospital (tertiary care center with 901 beds) between January 2002 and December 2016. Among them, we identified the patients newly diagnosed as NTM lung disease, and the clinical characteristics, CT findings, and prognosis of these patients were analyzed. Results: NTM was microbiologically identified in 168 patients (12.3%) with IP. Among them, 61 patients (4.5%) satisfied the diagnostic criteria of NTM lung disease (2007 ATS/IDSA statement) and were evaluated. Mean age of these patients was 69.7 ± 11.0 years and 23 patients were female. Body mass index was 21.3 kg/m2.%FVC predicted, %FEV1 predicted, and %DLco/VA were 83.8%, 87.6%, 73.4%, respectively. KL-6 and SP-D as markers of IP were 1,242 U/ml and 210 ng/ml, respectively. With regard to classification of IP, 35 patients had idiopathic IPs and 23 patients had connective tissue disease-associated IP. At the diagnosis of NTM lung disease, 24 patients received corticosteroid and/or immunosuppressive agents. The major species was Mycobacterium avium (36 patients), followed by M. intracellulare (17 patients), and M. kansasii (three patients). Other species were as follows: M. abscessus (one patient), M. avium and M. intracellulare (one), M. avium and M. abscessus (one), M. intracellulare and M. massiliense (one), and M. chelonae and M. abscessus (one). The noteworthy CT findings were wall thickening of cystic lesions such as traction bronchiectasis, honeycomb, or emphysematous change (19 patients, 31.1%), and consolidation (15 patients, 24.6%). In 22 patients (36.0%), dense fibrotic lesions made it difficult to specify NTM infected lesions. The nodular bronchiectatic lesion was presented in 14 patients (23.0%). Twenty one patients underwent multiple drug therapy. As for prognosis, a total of 30 patients died from various causes including acute exacerbation of IP (12 patients), bacterial pneumonia other than mycobacteria (seven), and chronic respiratory failure (four). Among the 30 patients, three died of NTM deterioration. Conclusions: This study showed that NTM lung disease was found in 4.5% of IP patients. The CT findings of IP and NTM lung infections were different from those of primary NTM lung disease. In clinical practice of IP, clinicians should note that NTM lung disease could occur in patients with IP.