[Differential diagnosis of pulmonary mycobacterial infection; radiological findings mimicking tuberculous or nontuberculous mycobacterial pneumonia].

Radiological imaging is one of the important clues for diagnosis of pulmonary mycobacterial infection. Differential diagnosis of pulmonary tuberculosis and nontuberculous mycobacterial infection is following; bacterial pneumonia, bronchopneumonia, mycoplasma pneumonia, pulmonary fungal infection, diffuse panbronchiolitis, sinobronchial syndrome, sarcoidosis, Wegener's granulomatosis, bronchiolealveolar carcinoma, pulmonary malignant lymphoma, and pneumoconiosis. Characteristic findings of bronchial tuberculosis are chronic productive cough with no radiological finding, lobar atelectasis, or mucoid impaction of bronchi. Radiologic findings of pulmonary mycobacterial infection are multiple infiltration, centri-lobular nodules which sometime adhere, cavity, and solitary nodule, however, these findings mimic bacterial pneumonia and bronchopneumonia especially in case of immunosuppressive patients. Pulmonary tuberculosis predominantly appears in upper lobe and the top of lower lobe of S6. Nontuberous mycobacterium pulmonary infection predominantly affects middle lobe and lingual lobe, accompanying with bronchial wall thickness and bronchiectasis. It is difficult to diagnose pulmonary mycobacterial infection using pulmonary imaging alone, therefore bacterial examination from sputum or bronchoalveolar lavage fluid should be necessary.