Point-of-Care Ultrasound Diagnosis of Diffuse Pulmonary Metastases: The Cannonball Sign

Cannonball pulmonary metastases are well characterized on radiographs and computed tomography of the chest, but their sonographic appearance on point-of-care ultrasound (POCUS) is not well described. We present a case of a 32-year-old man with a history of mixed germ cell tumor who presented with respiratory symptoms and tested positive for COVID-19. POCUS of the lung revealed numerous well-circumscribed subpleural lesions suggestive of metastatic disease, which helped differentiate them from COVID-19 pneumonia. Follow-up imaging confirmed diffuse metastases. This case highlights the potential utility of POCUS in detecting pulmonary metastases at the bedside and supports its growing role in acute care diagnostics.