Cardiac lymphoma causing severe pulmonary stenosis in a cat.

A nine-year-old, domestic shorthair cat was referred for investigation of a suspected renal mass, polyuria, polydipsia, hyporexia and weight loss of one month's duration; no respiratory signs were reported. On presentation, the cat had marked respiratory effort. Thoracic auscultation revealed reduced heart and lung sounds bilaterally. Transthoracic echocardiography revealed a large pleural effusion and an extensive, homogenous mass within the right ventricular outflow tract, invading the pulmonary valve and causing severe infundibular and valvular pulmonary stenosis and right atrial and ventricular dilatation. The mass extended to, and infiltrated, the right ventricular free wall. Postmortem examination confirmed the presence of a mass associated with the pulmonary valve extending into the right ventricle and infiltrating the right ventricular and right atrial myocardium, resulting in severe infundibular and valvular pulmonary stenosis. Histopathology showed disseminated intermediate to large cell lymphoma affecting the kidney, myocardium, pulmonary valve, pancreas, diaphragm and adrenal glands.