The Findings of Pulmonary Nocardiosis on Chest High Resolution Computed Tomography: Single centre experience and review of literature

Abstract

Objectives: Pulmonary nocardiosis is a rare opportunistic infection that is often encountered in immunocompromised patients, in particular those with the HIV infection and in solid organ transplant recipients. As the number of immunocompromised patients increase, the number of patients with pulmonary nocardiosis is also expected to increase. This study aimed to analyse both the chest high resolution computed tomography (HRCT) findings of patients with confirmed pulmonary nocardiosis and review the imaging features of pulmonary nocardiosis in the literature.

Methods: This retrospective study was conducted at The Royal Hospital, Muscat, Oman, to identify patients with a diagnosis of pulmonary nocardiosis between January 2006 and January 2019. Accordingly, nine patients with pulmonary nocardiosis were identified, but three patients were excluded as no chest HRCT images were available. Patient clinical presentation was recorded and chest HRCT images were retrospectively reviewed.

Results: A total of six patients were enrolled in this study. All were male and with a mean age of 41 ± 11 years. Three patients were immunocompromised, two of whom had undergone a renal transplant. The main HRCT findings were cavitary nodules/masses, non-cavitary nodules/masses, septal thickening, centrilobular nodules, ground glass opacities, consolidation, pleural effusion, pleural thickening, enlarged lymph nodes and necrotic lymph nodes.

Conclusion: Pulmonary nocardiosis shows various findings in a chest CT, the most common of which are pulmonary nodules and masses. Awareness of these findings can help radiologists with a diagnosis in the appropriate clinical settings.

Keywords: Computed Tomography; Oman; Pulmonary Nocardiosis.

Figure 1

A & B: Computed tomography (CT) scan (lung window setting) of the chest of a 42-year-old male post-renal transplant patient showing bilateral multiple pulmonary nodules of variable sizes; some of the nodules show central cavitation (arrow) and a cavitary mass in the posterior segment of the right upper lobe (arrowhead). C: CT scan of the chest of a 59-year-old male patient with pulmonary nocardiosis (lung window setting) showing bilateral multiple pulmonary nodules of various sizes; some of the nodules show a ground glass hallow. D: CT scan of the chest of a 28-year-old male patient (lung window setting) with glomerulonephritis on steroids showing bilateral lower lobe consolidation and bilateral pleural effusions.

Figure 2

Computed tomography (CT) chest scan of a 29-year-old male post-renal transplant patient showing a mass surrounded by ground glass halo in the right lower lobe (arrow) in the (A) mediastinal window and (B) lung window. CT chest scan of a 59-year-old male with pulmonary nocardiosis showing a mass with areas of low attenuation in the right lower lobe (asterisk) associated with a right pleural effusion. Pulmonary nodules are also seen in the left lower lobe in the (C) mediastinal window and (D) lung window (arrows).

Figure 3

Computed tomography chest scan in the mediastinal window of a (A) 59-year-old male with pulmonary nocardiosis showing a right paratracheal lymph node (arrow) and a (B) 42-year-old male with pulmonary nocardiosis showing a necrotic mediastinal lymph node (arrow).