Tomographic assessment of thoracic fungal diseases: a pattern and signs approach

Abstract

Pulmonary fungal infections, which can be opportunistic or endemic, lead to considerable morbidity and mortality. Such infections have multiple clinical presentations and imaging patterns, overlapping with those of various other diseases, complicating the diagnostic approach. Given the immensity of Brazil, knowledge of the epidemiological context of pulmonary fungal infections in the various regions of the country is paramount when considering their differential diagnoses. In addition, defining the patient immunological status will facilitate the identification of opportunistic infections, such as those occurring in patients with AIDS or febrile neutropenia. Histoplasmosis, coccidioidomycosis, and paracoccidioidomycosis usually affect immunocompetent patients, whereas aspergillosis, candidiasis, cryptococcosis, and pneumocystosis tend to affect those who are immunocompromised. Ground-glass opacities, nodules, consolidations, a miliary pattern, cavitary lesions, the halo sign/reversed halo sign, and bronchiectasis are typical imaging patterns in the lungs and will be described individually, as will less common lesions such as pleural effusion, mediastinal lesions, pleural effusion, and chest wall involvement. Interpreting such tomographic patterns/signs on computed tomography scans together with the patient immunological status and epidemiological context can facilitate the differential diagnosis by narrowing the options.

Keywords: Diagnostic imaging; Invasive fungal infections; Tomography, X-ray computed.

Figure 1

HIV-positive patient with pneumocystosis. High-resolution computed tomography of the upper lung lobes, showing diffuse ground-glass opacities in the pulmonary parenchyma and sparse small foci of consolidation.

Figure 2

Patient with acute lymphoid leukemia, febrile neutropenia, and angioinvasive fungal infection. A: Axial tomography scan of the chest showing an irregular nodule with a discrete ground-glass halo (halo sign). B: After antifungal therapy had been started, there was cavitation of the nodule, with an intracavitary nodule (air crescent sign).

Figure 3

Patient with untreated paracoccidioidomycosis. Axial high-resolution computed tomography scan of the chest, showing multiple sparse irregular nodules (arrows), some cavitary (arrowheads).

Figure 4

Patient with cryptococcosis. Contrast-enhanced axial tomography scan of the chest, with a mediastinal window setting, showing lobular peripheral consolidation with a central necrosis component (arrowhead).

Figure 5

Patient with paracoccidioidomycosis. Axial tomography of the chest, with a lung window setting, showing numerous sparse groups of micronodules and a lesion with the reversed halo sign in the left lower lobe (arrow).

Figure 6

Patient with miliary histoplasmosis. Axial tomography of the chest, with a lung window setting, showing micronodules with a random distribution.

Figure 7

Patient with a history of acute lymphoid leukemia and chronic necrotizing aspergillosis. Axial high-resolution computed tomography of the chest, showing chronic consolidations in the left lung lobes, accompanied by bronchiectasis, with a prominent, filled cavitary lesion in the left lower lobe (arrow).

Figure 8

Patient with histoplasmosis. Axial high-resolution computed tomography of the chest, showing centrilobular opacities and bilateral sparse foci of consolidation, in addition to a cavitary lesion in the right lower lobe. Small pneumothorax on the left.

Figure 9

Patient with saprophytic fungal infection. Axial tomography of the chest, with a lung window setting, showing a cavitary lesion in the middle lobe, with a mobile nodule in the interior (aerial crescent), a characteristic aspect of saprophytic aspergillosis (white arrow). As an additional finding, bronchiectasis in the same wolf (leaked arrow).

Figure 10

Patient with asthma and allergic bronchopulmonary aspergillosis. Axial tomography of the chest, with a lung window setting, showing predominantly central varicose bronchiectasis accompanied by bronchial parietal thickening (arrows).

Figure 11

Patient with acute myeloid leukemia and invasive pulmonary aspergillosis. Axial chest tomography with maximum intensity projection reconstruction showing centrilobular opacities grouped in a tree-in-bud arrangement (arrow).

Figure 12

Patient with fibrosing mediastinitis. Contrast-enhanced coronal tomography of the chest, with a mediastinal window setting and maximum intensity projection reconstruction, showing a right-sided subcarinal, hilar infiltrative lesion (arrow), obliterating the pulmonary artery of that side, with an extensive network of collaterals.