CT findings of pulmonary non-tuberculous mycobacterial infection in non-AIDS immunocompromised patients: a case-controlled comparison with immunocompetent patients

Abstract

Objective: To describe CT findings of non-tuberculous mycobacteria (NTM) pulmonary infection in non-AIDS immunocompromised patients (ICPs) and to compare these findings with those in immunocompetent patients.

Methods: From July 2000 to August 2007, 369 patients (mean age 58.3 years; 169 males and 200 females) with pulmonary NTM infection were retrospectively reviewed. Of these 369 patients, 24 ICPs (mean age 64.8 years; 15 males and 9 females) were identified. 16 patients had diabetes mellitus, and 6 patients had received long-term steroid therapy. One had received solid organ transplantation and one had received high-dose chemotherapy for haematological disease. 24 age- and sex-matched immunocompetent patients (mean age 64.6 years; 15 males and 9 females) were selected as the control group from the same registry. CT images were reviewed in consensus by three chest radiologists, who were blinded to immune status. Each lung lobe was evaluated in terms of extent of the lesion, bronchiectasis, parenchymal opacity and the presence of ancillary findings. results: A total of 287 lobes were evaluated in ICPs and the control group. The ICPs showed a higher prevalence of ill-defined nodules, with cavities and large opacity >2 cm with/without cavity (p=0.03, 0.04 and 0.02, respectively). Regardless of the immune status, the most common CT findings were bronchiectasis and ill-defined nodules without cavity.

Conclusion: The most common CT findings of pulmonary NTM infection in ICPs were bronchiectasis and ill-defined nodules, similar to those in the control group. Ill-defined nodules with cavity and large opacity >2 cm with/without cavity were more frequently found in ICPs.

Advances in knowledge: In patients affected by NTM infection, large opacities and cavitation in pulmonary nodules are more frequent in ICPs than in immunocompetent patients.

Figure 1.

Types of parenchymal opacities. (a) A 77-year-old female undergoing long-term steroid therapy; ill-defined nodules. CT scan shows multiple, ill-defined nodules in the right middle lobe and right lower lobe. (b) A 54-year-old male with diabetes mellitus (DM); well-defined nodules. CT scan shows well-defined nodules (black arrows) in the right middle lobe and left lower lobe. (c) A 54-year-old female with DM; large opacities. CT scan shows a large opacity >2 cm (black arrows), a large opacity ≤2 cm (arrowhead) and a well-defined nodule (white arrow) in the right lower lobe. Ill-defined nodules are also seen. (d) A 48-year old female with DM; large opacities. CT scan shows a large opacity >2 cm in the right middle lobe and left lingular segment.

Figure 2.

A 56-year-old female on steroid therapy for 1 year. The total disease extent was 10. (a, b) CT scan shows bronchiectasis with ill-defined nodules in the superior division of the left upper lobe. A cavity (black arrow) in an ill-defined nodule was also seen. The bronchiectasis score was 4. (c, d) CT scan shows a large opacity >2 cm, with a cavity and bronchiectasis in the left lower lobe. The bronchiectasis severity was 3. The bronchiectasis score was 9.

Figure 3.

A 54-year-old female with diabetes mellitus. The total disease extent was 20. (a–d) CT scan shows multiple large opacities and well-defined nodules, with a cavity in both lobes. Bronchiectasis was also seen. The bronchiectasis (black arrow in b) severity in the right middle lobe was 2.