Pulmonary nontuberculous mycobacterial infection: Radiologic manifestations

The nontuberculous mycobacteria (NTMB) are a group of bacteria that can inf ect the cervical lymph nodes, skin, soft tissues, and lung. Pulmonary NTMB disease is increasing in prevalence and is most commonly caused by Mycobact erium avium-intracellulare or M kansasii. Occasionally, M xenopi, M fortuit um, or M chelonae also causes pulmonary disease. Diagnosis of pulmonary NTM B infection is often difficult because isolation of the organism from sputu m or bronchoalveolar lavage fluid can represent airway colonization. The ra diologic manifestations of pulmonary NTMB infection are protean and include consolidation, cavitation, fibrosis, nodules, bronchiectasis, and adenopat hy. Pulmonary NTMB infection has five distinct clinicoradiologic manifestat ions: (a) classic infection, (b) nonclassic infection, (c) nodules in asymp tomatic patients, (d) infection in patients with achalasia, and (e) infecti on in immunocompromised patients. Although classic NTMB infection may be in distinguishable from active tuberculosis, it is usually more indolent. The radiologic features of nonclassic NTMB infection are characteristic: bronch iectasis and centrilobular nodules isolated to or most severe in the lingul a and middle lobe. In patients with acquired immunodeficiency syndrome, med iastinal or hilar adenopathy is the most common radiographic finding. Knowl edge of the full spectrum of clinical and radiologic features of pulmonary NTMB infection is important to facilitate diagnosis and treatment.