Radiographic features of pulmonary disease due to atypical mycobacteria

The chest radiographs and medical records of 40 patients with atypical mycobacterial pulmonary disease were reviewed. In 34 patients the infection was caused by M. avium-intracellulare, in five by M. kansasii, and in one by M. fortuitum. Ninety-eight percent had parenchymal disease characterized as fibroproductive; cavitation occurred in 38%. The progression of disease was slow, requiring about six years on average before radiographs showed a change in the disease. Common causes of a missed diagnosis of atypical mycobacterial pulmonary disease included the following: unchanging radiographs were viewed as showing inactive disease; a negative purified protein derivative test for M. tuberculosis was erroneously used to exclude mycobacterial disease; and a subsequently negative workup resulted in patients being diagnosed as having chronic obstructive pulmonary disease or bronchiectasis