Masaomi Marukawa1, Akihiko Taniguchi2, Goro Kimura3, Naomi Kunichika4, Shoichi Kuyama5, Yoshinobu Maeda2, Katsuyuki Kiura2, Nobuaki Miyahara6. 1. Department of Respiratory Medicine, Japan Organization of Occupational Health and Safety Kagawa Rosai Hospital, 3-3-1 Joto-cho, Marugame, Kagawa, 763-8502, Japan. Electronic address: mmarukawa@kagawah.johas.go.jp. 2. Department of Hematology, Oncology, Allergy and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Science, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan. 3. Department of Respirology and Allergy, National Hospital Organization Minami-Okayama Medical Center, 4066 Hayashima, Hayashima-cho, Tsukubo-gun, Okayama 701-0304, Japan. 4. Department of Internal Medicine, Japanese Red Cross Yamaguchi Hospital, 53-1 Yahatanobaba, Yamaguchi, 753-8519, Japan. 5. Department of Respiratory Medicine, Iwakuni Clinical Center, 1-1-1 Atago-cho, Iwakuni 740-8510, Japan. 6. Department of Medical Technology, Okayama University Graduate School of Health Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan.
Abstract
BACKGROUND: The prevalence of Mycobacterium avium complex (MAC) pulmonary disease (PD) is increasing significantly in Japan. Among the patterns of MAC-PD, a solitary pulmonary nodule (SPN) is less common and often resembles lung cancer. The aim of this study was to identify the clinical features of MAC-SPN. METHODS: SPNs culture-positive for MAC (definite cases) and culture-negative SPNs showing nucleic acid amplification test (NAAT)-positive status (probable cases) that presented between January 2007 and December 2017 were enrolled. The patients' clinical, laboratory, radiological, and microbiological findings and outcomes were investigated. RESULTS: This study included 28 patients (median age, 66 years; 16 men, 12 women). All patients were asymptomatic when the disease was detected. Median SPN size was 23.5 mm. Twenty-six patients underwent video-assisted thoracoscopic surgery, while the others underwent percutaneous needle biopsy for diagnosis. Granulomatous inflammation was confirmed in all cases. Microbiologically, the 28 cases were divided into 17 in the definite group and 11 in the probable group. In both groups, M. avium was predominant. There were no significant differences in clinical and radiological findings and follow-up periods between the 2 groups. After diagnosis, 6 patients received medical treatment, while the others did not. The median follow-up period was 42 months, and no recurrence was observed in both groups. CONCLUSIONS: MAC should be considered in the differential diagnosis of SPNs in asymptomatic patients. To overcome the difficulties in diagnosing MAC-SPN, this study underscores the importance of diagnostic interventions and identification of MAC by culture and/or NAAT in biopsied specimens.
BACKGROUND: The prevalence of Mycobacterium avium complex (MAC)pulmonary disease (PD) is increasing significantly in Japan. Among the patterns of MAC-PD, a solitary pulmonary nodule (SPN) is less common and often resembles lung cancer. The aim of this study was to identify the clinical features of MAC-SPN. METHODS: SPNs culture-positive for MAC (definite cases) and culture-negative SPNs showing nucleic acid amplification test (NAAT)-positive status (probable cases) that presented between January 2007 and December 2017 were enrolled. The patients' clinical, laboratory, radiological, and microbiological findings and outcomes were investigated. RESULTS: This study included 28 patients (median age, 66 years; 16 men, 12 women). All patients were asymptomatic when the disease was detected. Median SPN size was 23.5 mm. Twenty-six patients underwent video-assisted thoracoscopic surgery, while the others underwent percutaneous needle biopsy for diagnosis. Granulomatous inflammation was confirmed in all cases. Microbiologically, the 28 cases were divided into 17 in the definite group and 11 in the probable group. In both groups, M. avium was predominant. There were no significant differences in clinical and radiological findings and follow-up periods between the 2 groups. After diagnosis, 6 patients received medical treatment, while the others did not. The median follow-up period was 42 months, and no recurrence was observed in both groups. CONCLUSIONS:MAC should be considered in the differential diagnosis of SPNs in asymptomatic patients. To overcome the difficulties in diagnosing MAC-SPN, this study underscores the importance of diagnostic interventions and identification of MAC by culture and/or NAAT in biopsied specimens.