Mass confusion.

A patient is reported who presented to the hospital with a benign arrhythmia and what was initially believed to be a benign intracardiac tumour as imaged by transthoracic echocardiography and a first transesophageal echocardiogram. Comprehensive assessment with a second transesophageal echocardiogram revealed extensive extra- and intracardiac involvement by masses with many malignant-appearing features, including compression of vascular structures in the mediastinum. Peripheral biopsy yielded a diagnosis of high-grade lymphoma. The clinical, echocardiographic and radiological findings are discussed, as are the expected features of myxomae, and by comparison, common features of malignancy. The ability of transesophageal echocardiography, when comprehensively performed, to define the location and extent of mass lesions, and their physiological impact, such as compression of the pulmonary vasculature, by two-dimensional imaging and spectral Doppler are emphasized.