Vascular enlargement is often described as the dilatation of pulmonary vessels around and within the lesions on CT images (Fig. 4d). One previous study reported this particular CT manifestation on a RT-PCR-negative COVID-19 patient who was admitted to a hospital 6 days after symptom onset [4]. Although rarely reported, we found this manifestation in most of our cases, which might be attributed to the damage and swelling of the capillary wall caused by pro-inflammatory factors.