"A Double Twist" Presentation - A Case Report of Purulent Cardiac Tamponade following a Rare Complication of Small-Cell Lung Cancer Radiotherapy.

Background: Small cell lung cancer is an aggressive tumor with a poor prognosis that requires prompt treatment. While radiotherapy may enhance survival when superior vena cava syndrome is present, radiation therapy-induced pericardial disease can be a potential complication. Case Report: A 55-year-old man, who recently underwent radiotherapy for stage IV small-cell lung cancer complicated by superior vena cava syndrome, presented with chest pain and dyspnea. In the emergency room, he was dyspneic, hypotensive, and tachycardic. Pulmonary auscultation revealed the absence of lung sounds on the right. The initial electrocardiogram showed ST-segment elevation in lateral leads and in lead DII, with reciprocal changes in lead DIII. A bedside transthoracic echocardiogram revealed cardiac tamponade and emergent pericardiocentesis was performed, removing 500 ml of purulent fluid, resulting in an immediate clinical improvement. Thoracentesis was also performed, showing no empyema. Large spectrum empirical antibiotic therapy was started. Cultures from the pericardial fluid and peripheral blood grew multi-sensitive Conclusions: Although the most common causes of pericardial effusion in lung cancer are malignant, non-malignant etiologies should also be considered. This patient had an infectious pericardial effusion most probably due to a pericardial-mediastinal mass fistula caused by radiotherapy. This was a diagnostic challenge, both in the emergency room as well in the inpatient setting. LEARNING POINTS: Small cell lung cancer is a fast-growing cancer that exhibits aggressive behavior.In patients with lung cancer, malignant pericardial effusions are more common than non-malignant ones.Purulent pericardial effusions, especially those due to lung cancer, are rare in developed countries with very few reports in the literature.