POLYCYSTIC TUMOR OF THE ATRIOVENTRICULAR NODAL REGION IN A MAN WITH EMERY-DREIFUSS MUSCULAR-DYSTROPHY

Benign polycystic tumor of the atrioventricular nodal region is a lesi on associated with cardiac conduction defects with atrioventricular bl ock and sudden death. We present the clinical and light microscopical, immunohistochemical and ultrastructural findings of such a lesion in a young man with X-linked recessive Emery-Dreifuss muscular dystrophy who died suddenly. The tumor has not previously been described in this group of patients, who frequently suffers from cardiac electric insta bility and sudden death. Possible mechanisms by which the tumor may ca use arrhythmia are discussed and the presence of neuroendocrine cells in the lesion is emphasized.