OnBehalf Nicosia General Hospital We present the case of a young patient with large B-cell lymphoma causing severe extrinsic pulmonary stenosis. This patient presented to the emergency department with chest discomfort ,fatigue and dyspnea on minimal exertion. A loud ejection mid-systolic crescendo-decrescendo murmur with widely split S2 located in 2nd left parasternal border, raised the suspicion of pulmonary stenosis and patient underwent immediate transthoracic echocardiography as the first imaging modality of choice.On transthoracic echocardiography a large mass was seen, causing severe extrinsic pulmonary stenosis, and was further diagnosed as B-cell lymphoma after CT-guided biopsy. We discuss the high index of lymphoma suspicion in cases of pulmonary stenosis findings such as loud ejection murmur in pulmonic valve auscultation area, in otherwise healthy patients, with no history of congenital heart disease. Lymphoma and other mediastinal masses represent the most common aetiology of acquired pulmonary stenosis and should be suspected in otherwise healthy patients who present with clinical findings of pulmonary stenosis and vice-versa, pulmonary stenosis should be suspected in the presence of symptomatic mediastinal masses. Abstract P1302 Figure. Lymphoma PSAX