We report the clinical and autopsy findings of a young female suffering of complete heart block since the age of 11 and who suddenly died at the age of 32 because of a polycystic atrio-ventricular node tumor. In association with this tumor, we observed a hyperplasia of the islets of Langherans, a true thymic hyperplasia, bilateral multicystic ovaries, adrenal tissue heterotopia and clear cell adenomatosis in the right kidney. We suggest that the polycystic atrio-ventricular node tumor may be part of a complex syndrome with endocrine disorders and heterotopias.