An 81-year-old male was referred with a five-week history of progressive dyspnoea, dysphagia and dysphonia in conjunction with facial plethora on a background of coronary artery bypass grafting less than one year ago. Intraoperative assessment revealed a thickened pericardium with significant adhesions suggesting constrictive pericarditis although of unclear aetiology. Histopathology was not obtained.

Subsequent computed tomography showed a large mediastinal mass enveloping the great vessels and superior vena cava. Lesional core biopsy confirmed triple expressor, highly proliferative (Ki67 Greater-than 90%) diffuse large B-cell lymphoma.

Given myocardial involvement on follow-up positron emission tomography, concerns were raised for cardiac fitness and ventricular rupture pending anthracycline chemotherapy. Cardiac magnetic resonance was therefore sought which demonstrated pericardial invasion encasing the left anterior descending artery without left atrial or ventricular myocardial infiltration. Ejection fraction was also preserved at 58% in contrast to prior transthoracic echocardiography which measured Less-than 50%.

Based on these findings, an anthracycline-containing regimen was deemed feasible. As such, six cycles of alternating mini-RCHOP and R-CVP plus six fractions of superior mediastinal radiotherapy totalling 24 Gray was pursued conferring patient survival beyond three months. In summary, this case highlights the utility of cardiac magnetic resonance imaging in defining invasive mediastinal lymphoma to inform cardiac fitness for therapy.