A 25 year-old male resident presented with a 72 h history of fever up to 38 ºC, odynophagia, myalgia and general malaise. Laboratory studies only showed increased C-reactive protein (23 mg/L, normal range 0-5 mg/L). D-dimer was 0,23 μg / ml which is normal.
A chest X-ray was performed due to a suspicion of a COVID-19 infection.
A consolidation in the posterior region of the left lower lobe was seen in an anteroposterior and lateral chest radiographs. In a chest non-enhanced CT a consolidation surrounded by ground glass opacities consistent with halo sign and air bronchogram inside was confirmed in the apical segment of the left lower lobe.
The World Health Organization (WHO) declared a pandemic caused by a new coronavirus , the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in January 2020 [2, 3]. Six types of coronavirus have been described that cause human infection , especially severe respiratory disease . It should be noted those responsible for causing severe acute respiratory disease (SARS) and the Middle East respiratory syndrome (MERS), both considered zoonotic infections  which share 85% of homology with SARS-CoV-2 .
The disease caused by SARS-CoV-2 is named coronavirus disease 2019 (COVID-19) [2-4], life-threatening pneumonia  and it is spread by human contact [1, 2, 4] and respiratory droplets . Fever, dry cough, fatigue, and respiratory distress are the main symptoms [1, 4].
Transmission can occur during the incubation period or in asymptomatic stages .
Reverse transcription-polymerase chain reaction (RT-PCR)  is the gold standard diagnostic tool [3, 4] although some patients reveal false-negative results [2, 3] due to its high specificity and low sensitivity , especially in early stages  which may be a problem for early diagnosing and isolation measures .
Imaging techniques, especially chest X-ray and chest CT, have become important diagnostic and management tools in patients with suspected infection because they can be positive even before symptoms or positive laboratory test results [2, 3] with a higher sensitivity (98%) than RT-PCR (78%) . Moreover, due to its wide availability , imaging has proven to be essential in the evaluation of the severity and progression of the disease .
Ground glass opacifications (GGO) and consolidations [2, 3, 5] with bilateral, up to 75% of cases , and multifocal affectation [2-4] in the peripheral [2-4] and posterior  regions and involvement in the lower lobes [2, 3] are the most frequent signs seen on chest CT scan. Vascular enlargement, septal thickening, air bronchogram sign, air trapping, crazy paving pattern, halo sign and reversed halo sign can be also seen although less frequently [2-4].
As pulmonary involvement progresses, seen in 75% of patients, coalescence of the infiltrates and involvement of the upper pulmonary lobes are observed  with an increase in number, size, and density of the consolidations [3, 4].
The patient was discharged and made a full recovery at home with minor symptoms. Control RT-PCR 4 weeks after the initial diagnosis was negative.
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 Li, X., Zeng, X., Liu, B., & Yu, Y. (2020). COVID-19 infection presenting with CT halo sign. Radiology: Cardiothoracic Imaging, 2(1), e200026.