Objective: To identify the prevalence of risk factors for pulmonary non-tuberculous mycobacterial (NTM) disease in a Japanese population.Patients and Methods: We reviewed 337 consecutive Japanese patients (210 women) with pulmonary NTM disease, including 225 patients with Mycobacterium avium complex (MAC) disease (95.8%) at our hospital during 2006–2017. We calculated the prevalence of risk factors reported in Western countries among mycobacterial species.Results: Pulmonary MAC disease cases comprised 78.2% of pulmonary NTM patients in their 40s, increasing to 100% at age ≥80 years. Body mass index (BMI) was <18.5 in approximately 40% of patients, which was significantly higher than the prevalence of underweight in the Japanese population. The percentage of male heavy smokers (Brinkman index ≥600) was 58.2% of pulmonary NTM disease and was high for all mycobacterial species. In pulmonary MAC disease, systemic factors were observed in the order of malignant tumors (other than lung cancer), diabetes, rheumatoid arthritis, and tuberculosis. Local factors were observed in the order of bronchiectasis, chronic obstructive pulmonary disease, lung cancer, and bronchial asthma.Conclusion: The risk factors reported in Western countries were relatively highly prevalent among Japanese pulmonary NTM disease patients. This observation may help elucidate disease onset mechanisms.

Objective: Histological verification of epithelioid cell granuloma is important in diagnosing sarcoidosis; tissue sampling is a worldwide requirement. In 2006, to reduce medical expenses and avoid invasive procedures, diagnostic criteria without histological verification were permitted by the Japanese government. In 2015, new diagnostic criteria, allowed clinical diagnoses based on only respiratory, ocular, and cardiac systems with at least a two-system involvement, increasing the need to sample tissue from clinically unevaluable organs in suspected sarcoidosis. This study aimed to compare the characteristics of patients who were diagnosed with sarcoidosis according to the 2006 and 2015 criteria.Materials and Methods: Using the 2015 version, we re-evaluated the characteristics of 264 patients with diagnosed or suspected sarcoidosis according to the 2006 criteria, at Jichi Medical University Hospital between 2004 and 2012 (clinical diagnosis, 84; histological diagnosis, 117; suspected sarcoidosis 63).Results: Thirty-nine patients were diagnosed with suspected sarcoidosis due to the absence of at least a two-system involvement; two patients had insufficient laboratory data suggestive of sarcoidosis. Six patients moved from suspected sarcoidosis to a histological diagnosis because of a greater leniency in the criteria for supportive findings. The 2015 diagnostic criteria excluded patients with organ involvement without a requirement for systemic steroids from the clinical diagnosis group. A case of schwannoma, erroneously placed in the clinical diagnosis group by the 2006 criteria, was reclassified according to the 2015 criteria.Conclusion: The 2015 version is preferable for clinically diagnosing sarcoidosis, even without histological specimens, and provides guidance for indications for systemic treatment.

Objective: Pulmonary mycobacterium avium complex (MAC) disease is increasing significantly worldwide. Several studies have investigated the clinical features of pulmonary MAC disease in the setting of cancer. Here, we aimed to clarify the clinical characteristics of patients with cancer with recent onset of pulmonary MAC disease and the effect of cancer on the onset of this disease.Patients and Methods: Of the 323 consecutive Japanese patients newly diagnosed with pulmonary MAC disease at Jichi Medical University Hospital between and 2006–2017, we retrospectively reviewed 79 consecutive patients with cancer.Results: Seventeen patients had lung cancer (21.0%), while 62 had non-lung cancer. Of the 17 patients with lung cancer, 16 had adenocarcinoma of which 10 had stage I to III disease; 8 of the 10 patients had not received chemotherapy. Sixteen patients with lung cancer had a MAC infection in the ipsilateral lung. Notably, 9 of the 11 lung cancer patients who did not undergo surgery had a MAC infection in the affected lobe. Of the 39 patients with the most common types of non-lung cancer (14 had gastric cancer, 13 had colorectal cancer, and 12 had breast cancer), 22 had stage I to III disease, and 18 of these 22 had not received chemotherapy.Conclusion: Lung cancer may act as a local factor contributing to the onset of pulmonary MAC disease in the ipsilateral lung. However, the underlying mechanism by which a history of cancer might affect the onset of pulmonary MAC disease remains unclear. Further investigation into this mechanism is needed.