Shortness of breath and unexpected imaging findings

The differential diagnosis for this patient included pneumonia, tuberculosis, pneumothorax, pleural effusion, pericardial effusion, and lung cancer. A view of the right lung base in the midaxillary line showed fluid above the diaphragm and a "spine sign" suggestive of pleural effusion [1] but, more interestingly, also showed cardiac activity (Fig. 1). The result is ipsilateral shift of intrathoracic structures, loss of lung volume, limitation of chest wall excursion, and a restrictive pattern of lung physiology [2-4].