Solitary rhabdomyoma of the heart. Clinically silent case with sudden, unexpected death in an 11-month-old boy.

We report a case of cardiac rhabdomyoma leading to sudden, unexpected death in an 11-month-old child. Autopsy disclosed a firm nodular tumor located in the anterior part of the interventricular septum and anterior wall of the left chamber. The tumor bulged into the cavity of the ventricle and caused appreciable narrowing of the outflow tract. Histologically, the typical "spider cells" characteristic for cardiac rhabdomyoma could be found. Sections cut from alcohol-fixed tissues and stained in water-free PAS showed that these cells contained massive amounts of diastase-digestible PAS-positive material, presumably glycogen. No evidence of tuberous sclerosis was detected. Sudden death was attributed to cardiac arrest due to irritation of the conducting system by the tumor.