An unusual site for the AV node tumor: report of two cases.

Atrioventricular (AV) node tumors are very uncommon primary cardiac tumors located exclusively in the AV nodal region. The nomenclature has been diverse according to different histogenetic theories proposed since the first description in 1911. Histochemical, ultrastructural, and immunohistochemical studies have demonstrated its endodermal origin. Patients with these tumors can develop complete heart block or sudden death, but the tumor can also be an incidental finding at autopsy. We present two accidental deaths cases in which multiple foci of atrioventricular node tumor (Case 1) and an isolated cyst (Case 2) were observed in the atrial septum, sparing the conduction system.