Immunoblastic lymphoma presenting with syncope due to sinoatrial node disease.

A 68 year old man presented with syncope associated with episodes of sinus arrest. He responded to insertion of a demand pacemaker. During investigation he was noted to have generalized lymphadenopathy and biopsy revealed that he had an immunoblastic lymphoma. Before further assessment could be made, he developed rapid atrial fibrillation, resistant to several anti-arrhythmic agents and died several days after admission. At autopsy a nodular plaque of lymphoma was found to overly the sinoatrial node which was markedly fibrosed with evidence of lymphomatous infiltration of the surrounding microvasculature.