Chest-CT mimics of COVID-19 pneumonia-a review article

Abstract

Coronavirus disease 2019 (COVID-19) emerged in early December 2019 in China, as an acute lower respiratory tract infection and spread rapidly worldwide being declared a pandemic in March 2020. Chest-computed tomography (CT) has been utilized in different clinical settings of COVID-19 patients; however, COVID-19 imaging appearance is highly variable and nonspecific. Indeed, many pulmonary infections and non-infectious diseases can show similar CT findings and mimic COVID-19 pneumonia. In this review, we discuss clinical conditions that share a similar imaging appearance with COVID-19 pneumonia, in order to identify imaging and clinical characteristics useful in the differential diagnosis.

Keywords: COVID-19 pneumonia; Chest HRCT; Differential diagnosis.

Fig. 1

a–c Axial HRCT images of three different patients with COVID-19 pneumonia (a–c) showing bilateral, patchy ground-glass parenchymal opacities with prevalent peripheral and mid-lower lobes distribution

Fig. 2

a–b Axial HRCT images of two patients with COVID-19 pneumonia showing an organizing pneumonia pattern (a), with bilateral ground-glass opacities, lower lobes prevalent distribution, and the classic reverse halo sign, or atoll sign (black arrows in a), in the right lower lobe; and a “crazy paving” pattern (b) resulting from ground-glass opacities superimposed to interlobular septal thickening (black arrows in b)

Fig. 3

Axial HRCT scan of a patient with H1N1 pneumonia shows bilateral patchy ground-glass opacities associated with small areas of consolidation (black arrows)

Fig. 4

a–c Axial HRCT images of three patients with different stages of Pneumocystis jiroveci pneumonia showing, at an early stage (a), bilateral, diffuse ground-glass opacities with a mosaic attenuation pattern; and in advanced stages (b–c) more extensive ground-glass opacities and parenchymal, variable in shape and size cysts (arrows in b and c), whose rupture can sometimes lead to pneumothorax (white * in c)

Fig. 5

a–b Axial supine (a) and prone (b) HRCT images of a patient with non-fibrotic hypersensitivity pneumonitis showing small bilateral ground-glass centrilobular nodules (a) and bilateral patchy ground-glass opacities with lobular air-trapping (arrows in b) resulting in a mosaic pattern attenuation

Fig. 6

a–b Axial HRCT images of two patient with acute eosinophilic pneumonia (a–b) show parenchymal ground-glass opacities and consolidations with a peripheral and lower lobes prevalent distribution; thickening of interlobular septa (black arrows in b) and broncho-vascular bundles (white arrows in b) are also seen

Fig. 7

a–b Axial HRCT images of two different patients with diffuse alveolar hemorrhage show bilateral, diffuse hazy ground-glass (a–b) and centrilobular opacities (black circle in a) with subtle sub-pleural sparing and a prevalent middle/lower lung zones distribution or “batwing” appearance

Fig. 8

a–b Axial HRCT images of two patients with acute exacerbation of interstitial lung disease (ILD) show extensive bilateral ground-glass opacities and focal consolidations, superimposed to a background parenchymal pattern consistent with an underlying ILD compatible with non-specific interstitial pneumonia pattern (a) and with usual interstitial pneumonia pattern (b)

Fig. 9

a–d Axial HRCT images of two patients who developed drug-induced lung injury secondary to amiodarone (a–b) and to anthracyclines (c–d) therapy, show bilateral patchy ground-glass opacities, consolidations, and fibrotic septal thickening (a–b); and extensive bilateral ground-glass opacities involving all lobes with subpleural sparing (c–d)