대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Nontubeculous Mycobacterial (NTMB) Pulmonary Infection

Radiologic Findings

On chest PA projection, nodular and partly reticular increased opacities are seen in both hilar areas. These lesions are located in the areas of right middle lobe and lingular segment of left upper lobe on lateral projection (not shown). Also seen is associated volume decrease and bronchiectasis in above mentioned areas. Chest CT shows the findings of bronchiectasis and bronchiolitis, predominantly in right middle lobe and lingular segment of left upper lobe, raising the possibility of nontuberculous mycobacteria infection. Underlying chronic obstructive pulmonary disease is also noted.
Sputum smear and culture was done and exposed positive AFB smear. Mycobacterium abscessus was isolated in 11 days incubation using the Lowenstein-Jensen culture media.

Brief Review

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.

References

1. Erasmus JJ, McAdams HP, Farrell MA, Patz EF. Pulmonary nontuberculous mycobacterial infection: Radiologic manifestations. RadioGraphics 1999; 19: 1487-1503
2. Goo JM, Im JG. CT of tuberculosis and nontuberculous mycobacterial infections. Radiol Clin North Am 2002; 40: 73-87

Keywords

Lung, Infection, Bacterial infection, NTM, Nontubeculous Mycobacterial (NTM) Pulmonary Infection