Rapid Growth of Lung Adenocarcinoma Presenting as Cardiac Tamponade

Background: Lung adenocarcinoma is the most common type of non-small cell lung cancer and the leading cause of cancerrelated death in the United States.The disease often presents late in its course and commonly metastasizes to numerous locations.Pericardial effusion is an uncommon but known complication of lung adenocarcinoma that often presents asymptomatically and is usually found postmortem.Case Report: A 69-year-old female with an active 80 pack-year history of tobacco use presented to the emergency department with acute dyspnea and was found to have cardiac tamponade secondary to a malignant pericardial effusion from lung adenocarcinoma.A year prior, an incidental computed tomography scan of the chest showed a 9-mm solid subpleural nodule at the peripheral right upper lobe and a 10-mm subsolid subpleural nodule at the peripheral left upper lobe; however, the patient did not follow up with a physician to establish care.Our patient's presentation was a rare and severe manifestation of advanced lung cancer, particularly in the context of rapid progression from previously identified but unmonitored pulmonary findings.Conclusion: This case highlights the potential for aggressive disease progression even in lesions that may initially appear indolent, underscoring the critical importance of adherence to pulmonary nodule follow-up guidelines and timely evaluation of high-risk patients.