Mediastinal masses are occasionally involved in extrinsic compression of heart structures such as cardiac chambers, great vessels, and their branches. In rare cases, this can lead to haemodynamic compromise. Echocardiography is key to identifying and describing salient features that might explain a patient's symptoms, and contributes valuable prognostic information. Here, we report a case study of a young male patient who presented with cardiac symptoms and was referred to our outpatient department for a routine transthoracic echocardiogram revealing an unusual presentation of right ventricular outflow tract obstruction, pulmonary valve compression, and pulmonary stenosis secondary to a large extracardiac mass.