Young-Onset, ROS1-Rearranged Adenocarcinoma of the Lung With Cardiac Tamponade: A Case Report.

Adenocarcinoma with ROS1 rearrangement is rare. Carcinomatous pericarditis is generally seen in advanced stages and is a life-threatening condition. A 21-year-old male was admitted to our hospital because of severe dyspnea due to cardiac tamponade identified on echocardiography. A diagnosis of ROS1-rearranged adenocarcinoma of the lung was made from the pathological and gene mutation analyses of the cell block from his pericardial fluid. Oral administration of entrectinib was highly effective, and his serum carcinoembryonic antigen (CEA) level improved from 247 to 10.8 ng/mL. The present case has clinical significance because a pathological and genetic diagnosis was made from the pericardial effusion fluid, and the clinical manifestations of cardiac tamponade due to lung cancer were well controlled by the administration of entrectinib.