We describe a case of a systemic-to-pulmonary venous shunt secondary to superior vena cava obstruction in a patient with newly diagnosed non-Hodgkin lymphoma. This rare condition manifested with symptoms of dyspnea and hypoxemia that were out of proportion to the pleural effusion diagnosed on chest imaging. Standard treatment of such rare collateral plexuses is observation. However, it is important for clinicians to be cognizant that in rare cases such plexuses can lead to right-to-left shunt complications such as embolism.