Cannonball appearance, a tricky yet underrated imaging manifestation of COVID-19

Spreading swiftly across the borders and over the seas, severe acute respiratory syndrome-related coronavirus-2 (SARS-COV-2), as causative pathogen of coronavirus disease 2019 (COVID-19), is currently the main global public health concern. "Cannonball appearance," as a rare and yet underrated CT feature of COVID-19 pneumonia, has been typically linked to certain hematogenous pulmonary metastases and some inflammatory/infection conditions, including tuberculosis, but no other viral or atypical pneumonia. Cannonball appearance can bring diagnostic dilemmas and difficulties in monitoring treatment response in patients with or suspicious for hematogenous pulmonary metastasis. Hereby, we report two cases of COVID-19 delta variant-induced pneumonia manifesting unusually in chest CT scan with cannonball appearance.