Dilated cardiomyopathy in Noonan's syndrome: a first autopsy case

The first autopsy case of dilated cardiomyopathy associated with Noonan's syndrome is described. A 9-month-old girl with Noonan's syndrome died from cardiac failure. Autopsy showed biatrial and biventricular enlargement of the heart. The posterior half of the ventricular septum and right ventricular wall were remarkably thin. Other parts of the wall were nearly normal in thickness, but both ventricular cavities were dilated. Microscopically, the myocardium of both ventricles consisted of mainly abnormally thinned, elongated, and loosely arranged myocardial fibers lacking immunoreactivity to anti-dystrophin antibody. Myocardial disarray was not found except for where it normally existed. The abnormal changes of the myocardial fibers were considered to be primary. Common cardiomyopathy associated with Noonan's syndrome is a hypertrophic type. Various types of cardiovascular abnormality associated with Noonan's syndrome, including dilated cardiomyopathy, might be disclosed by further investigation and precise diagnosis of Noonan's syndrome.