Differential diagnosis of COVID-19 at the chest computed tomography scan: A review with special focus on cancer patients

Table 1 Summary of the studies included in the systematic review

Ref.	Yr	Type of study	Patients, n	Disease in differential diagnosis	Radiological similarities with COVID-19 disease	Radiological discrepancy with COVID-19 disease	Laboratory findings
Dai et al[16]	2020	Case series	4 pts COVID-19 positive. 1 pts heart failure induced pulmonary edema. 1 pts rheumatic pneumonia.	Heart failure induced pulmonary edema. Rheumatic pneumonia.	Local or multiple GGOs. Patchy high-attenuation patterns. Sporadic or local interlobular septal thickening. Patchy GGOs and consolidations; interlobular septal thickening.	Butterfly sign. Peribronchial cuffing. Redistribution of blood flow in both lungs.	Normal WBC count, D-dimer, hs-CRP. RT-PCR for SARS-CoV-2 negative. Normal WBC and lymphocyte count, high hs-CRP, D-dimer, rheumatoid factor. RT-PCR for SARS-CoV-2 negative.
Orlandi et al[17]	2020	Case report	-	Systemic sclerosis ILD	Bilateral GGOs with or without consolidations. Reticulations.	Limited to lower lobes. Honeycombing pattern.	RT-PCR for SARS-CoV-2 negative
Shenavandeh et al[18]	2020	Case report	1	Granulomatosis with polyangiitis	GGOs and consolidation	Nodules and mass lesions	-
Chen et al[20]	2020	Case report	1	Pulmonary contusion	GGOs and consolidation	More consolidations. Less combined with pleural effusion and subpleural atelectasis. Different time evolution of lesions.	High WBC count and mild decreased of lymphocyte count
Mazouz et al[19]	2020	Case report	1	Fat embolism	Bilateral GGOs	Central and peripherical involvement	High CRP, alkalosis with hypoxemia, normal lymphocyte count. RT-PCR for SARS-CoV-2 negative.
Zhang et al[29]	2020	Retrospective	157 pts COVID-19. 374 pts with early lung cancer.	Early lung cancer	Air bronchogram. Cystic change.	Less lobes and segments involved. Unilateral oval lesions. Pure or mixed GGOs. Lobulated sign, pleural retraction and vessel convergence sign. Less lymphadenopathies and pleural effusion.	Higher WBC and lymphocyte count, lower D-dimer level.
Zeng et al[28]	2020	Retrospective	112 pts COVID-19 positive or suspected. 4 pts with radiation pneumonitis.	Radiation pneumonitis	GGOs with consolidation. Air bronchogram. Irregular intralobular or interlobular septal thickening. Fibrosis in late stage.	Onset within 6 mo after radiation. Slow evolution. Lesions confined to radiation fields.	High WBC count, D-Dimer, CRP and PCT, marked lymphopenia. RT-PCR for SARS-CoV-2 negative.
Himoto et al[27]	2020	Retrospective	21 pts COVID-19 positive. 15 pts with viral or bacterial pneumonia.	Pneumococcal pneumonia, Moraxella pneumonia, Legionella pneumonia, not-specified bacterial or viral pneumonia. Pneumocystis pneumonia and interstitial pneumonia.	Bilateral peripherical GGOs. No cavitation, airway abnormalities, pleural effusion, and mediastinal lymphadenopathy.	Less lobes involved. No rounded morphology lesions.	RT-PCR for SARS-CoV-2 negative
Luo et al[22]	2020	Retrospective	30 pts COVID-19 positive. 43 pts with viral or bacterial pneumonia.	Influenza pneumonia, Pneumocystis carinii pneumonia, Mycoplasma pneumonia and CAP.	GGOs with or without consolidation	Less lobes involved. Peribronchovascular distribution. Centrilobular nodules. Bronchial wall thickening.	WBC and lymphocyte count normal, but lower in COVID-19 positive patients. RT-PCR.
Xie et al[26]	2020	Retrospective	12 pts COVID-19 positive. 16 pts COVID-19 negative.	COVID-19 negative	Bilateral multiple lung involvement, large irregular/patchy opacities, rounded opacities and linear opacities, crazy-paving patterns, interlobular septal, pleural and peribronchovascular interstitial thickening, air bronchograms, tree-in-bud patterns.	More central distribution of lesions. Less frequent rounded opacities.	Higher level of neutrophil count in COVID-19 negative. RT-PCR.
Bai et al[21]	2020	Retrospective	219 pts COVID-19 positive. 205 pts with viral pneumonia.	Viral pneumonia	Bilateral, multiple GGOs, consolidation, nodules. Septal thickening.	More central + peripheral distribution. More air bronchogram, pleural thickening, pleural effusion and lymphadenopathy.	Higher WBC and lymphocyte count in patients with viral pneumonia. RT-PCR.
Chi et al[32]	2020	Retrospective	17 pts COVID-19 positive. 51 pts with viral or bacterial pneumonia.	Influenza A and B. Adenovirus. Chlamydia pneumonia. Mycoplasma pneumonia.	-	INFLUENZA A: scattered and patchy shadows and nodular shadows in both lungs. INFLUENZA B: subpleural patchy shadows. ADENOVIRUS: consolidation near the pleura. CHLAMYDIA PNEUMONIAE: multiple GGOs and consolidations in both lungs. MYCOPLASMA PNEUMONIAE: bronchial wall thickening, centrilobular nodules, GGOs and consolidation.	Higher WBC count, RT-PCR
Li et al[24]	2020	Retrospective	43 pts COVID-19 positive. 49 pts with CAP.	CAP	-	More nodular or consolidation shadows with or without patchy GGOs. Less fine mesh changes, small vessels dilatated, bronchiectasis and lesion with long axis parallel to the pleura.	RT-PCR
Liu et al[25]	2020	Retrospective	165 pts COVID-19 positive. 118 pts with CAP.	CAP	-	More central distribution. More frequent single lesion. GGOs rapid changes in consolidation. Fibrous cord and bronchial wall thickening.	Normal WBC count, higher lymphocyte count and CRP. RT-PCR.
Zhou et al[31]	2020	Retrospective	149 pts COVID-19 positive. 97 pts with CAP.	CAP (Streptococcus. pneumoniae)	-	More consolidation lesions, bronchial wall thickening, centrolobular nodules and pleural effusion. Less GGOs, crazy paving sign and abnormally thickened interlobular septa.	High WBC count, neutrophils count and CRP. Rt-PCR.
Liu et al[23]	2020	Retrospective	122 pts COVID-19 positive. 48 pts with influenza pneumonia.	Influenza pneumonia	GGOs with consolidation. Nodules. Linear opacities. Interlobular septal thickening tree-in-bud sign.	More nodules, pleural effusions and tree-in-bud sign. Central + peripheral distribution.	RT-PCR for influenza or SARS-CoV-2.
Zhao et al[33]	2020	Retrospective	31 pts COVID-19 positive. 18 pts with influenza pneumonia.	Influenza pneumonia	-	More consolidations and pleural effusions.	RT-PCR
Wang et al[30]	2020	Retrospective	13 pts COVID-19 positive. 92 pts with influenza pneumonia.	Influenza pneumonia	GGOs and GGOs with consolidation	Inferior lobe involved. Cluster-like GGOs. Lesion with vague margin. Bronchial wall thickening.	Normal WBC count. Low lymphocyte count in Influenza B. No significative difference between two groups. RT-PCR.

pts: Patients; GGO: Ground-glass opacity; ILD: Interstitial lung disease; CAP: Community acquired pneumonia; WBC: White blood count; hs-CRP: High sensitivity C-reactive protein; RT-PCR: Reverse transcriptase polymerase chain reaction; SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2; PCT: Procalcitonin; COVID-19: Coronavirus disease 2019; CRP: C-reactive protein.