[The pathophysiological concept of nontuberculous mycobacterial diseases and pulmonary Mycobacterium avium complex disease].

Although nontuberculous mycobacteria (NTM) were initially isolated shortly after Mycobacterium tuberculosis, it has not been confirmed as true human pathogens until the 1930s. Only around 30 NTMs among more than 150 identified can infect to human, and cause pulmonary, lymph node, skin, soft tissue, bone, and disseminated diseases. NTM diseases, especially pulmonary, appear to be increasing all over the world. M. avium complex (MAC) and M. kansasii were the most frequent pulmonary pathogens. There are three forms in MAC respiratory infection; "fibrocavitary", "nodular/bronchiectatic" and "hot tub lung". Fibrocavitary form prefers apical bulla and cavity by pre-existing disease in smoking males. Nodular/bronchiectatic form involves middle lobe or lingula predominantly in non-smoking females. There must be the genetic susceptibility, but details are unknown.