Sudden cardiac death due to arrhythmogenic right ventricular cardiomyopathy and cystic tumor of the AV node.

An 18-year-old white male collapsed suddenly in his home and died. At autopsy, the right ventricle of the decedent was noted to be dilated with marked thinning of the wall focally. Microscopically, the myocardium of the right ventricle was noted to be significantly thinned focally, where transmural infiltration with fibroadipose tissue was noted. Depending on the criteria utilized to render such a diagnosis, these findings were consistent with arrhythmogenic right ventricular cardiomyopathy (ARVC). Subsequent microscopic examination of the SA and AV node, however, revealed the presence of a cystic tumor of the AV node (CTAVN), a known cause of sudden death from arrhythmia. The case represents the first reported case of ARVC and CTAVN occurring together in the same individual.