The nontuberculous mycobacteria (
NTMB) are a group of bacteria that can infect the cervical lymph nodes, skin, soft tissues, and lung. Pulmonary
NTMB disease is increasing in prevalence and is most commonly caused by Mycobacterium avium-intracellulare or M kansasii. Occasionally, M xenopi, M fortuitum, or M chelonae also causes
pulmonary disease. Diagnosis of pulmonary
NTMB infection is often difficult because isolation of the organism from sputum or bronchoalveolar lavage fluid can represent airway colonization. The radiologic manifestations of pulmonary
NTMB infection are protean and include consolidation, cavitation,
fibrosis, nodules,
bronchiectasis, and
adenopathy. Pulmonary
NTMB infection has five distinct clinicoradiologic manifestations: (a) classic
infection, (b) nonclassic
infection, (c) nodules in asymptomatic patients, (d)
infection in patients with
achalasia, and (e)
infection in immunocompromised patients. Although classic
NTMB infection may be indistinguishable from active
tuberculosis, it is usually more indolent. The radiologic features of nonclassic
NTMB infection are characteristic:
bronchiectasis and centrilobular nodules isolated to or most severe in the lingula and middle lobe. In patients with
acquired immunodeficiency syndrome, mediastinal or hilar
adenopathy is the most common radiographic finding. Knowledge of the full spectrum of clinical and radiologic features of pulmonary
NTMB infection is important to facilitate diagnosis and treatment.