Cardiomyopathy - Histiocytoid

The myocytes in this photograph have taken on an oncocytic appearance. This entity has many synonyms including oncocytic CM, infantile CM, focal lipid CM, congenital CM. As in all oncocytes, these cells show abundant, large mitochondria on EM.

This entity occurs in infants and small children. It is frequently associated with central nervous system anomalies and with oncocytic cells in various glands. The patients are prone to serious, often fatal, arrhythmias.

Hypertrophic cardiomyopathy (myofiber disarray and fibrosis)

This photomicrograph is from the septum in a case of hypertrophic obstructive CM. Note myofiber disarray with bundles running in all directions. Interstitial fibrosis is also present. Unfortunately, disarray is not pathognomic of HOCM.

Hypertrophic cardiomyopathy (HCM) is a relatively rare but deadly syndrome. It can result in sudden death, especially in younger patients. Sudden death is not always preceded by earlier symptoms. The disease has a genetic basis with defects in the genes encoding various sarcomeric proteins. The hallmark is inappropriate myocardial hypertrophy. IHCM can be obstructive or nonobstructive. When left ventricular tract outflow tract obstruction occurs, it is related to asymmetric septal hypertrophy and to anterior systolic motion of the anterior leaflet of the mitral valve. There is also impaired left ventricular filling due to diastolic dysfunction. Hypertrophic cardiomyopathy with similar pathological findings can be seen in the infant of a diabetic mother, in which case it is transient if the infant survives.

Arrhythmogenic cardiomyopathy (ACM)

This trichrome-stained section of the right ventricle is from a teen-aged boy who died suddenly after physical exertion.  He was of Italian extraction but had no family history of sudden death. The myocardium in this area is almost entirely replaced by fat.

There are many synonyms for this entity including arrhythmogenic right ventricular dysplasia, arrhythmogenic ventricular dysplasia, arrhythmogenic right ventricular cardiomyopathy, and arrhythmogenic ventricular cardiomyopathy. The disease is associated with sudden death in youths, particularly during exercise. A century ago, in the time of Osler, there were references to parchment heart, possibly the same entity. Another entity, Uhl’s anomaly, may also be related but is usually found in an infant or young child with congestive heart failure rather than in cases of sudden death. Pathological findings include a thin right ventricular wall which transilluminates well and fibrofatty replacement of myocardium, especially prominent in, but not limited to, the right ventricle. Many cases are familial with peak onset at ages 16-35 years. The pattern of inheritance is autosomal dominant.

Arrhythmogenic cardiomyopathy (ACM)

This trichrome-stained section of the right ventricle is from a teen-aged boy who died suddenly after physical exertion.  He was of Italian extraction but had no family history of sudden death. The myocardium in this area is almost entirely replaced by fat.

 There are many synonyms for this entity including arrhythmogenic right ventricular dysplasia, arrhythmogenic ventricular dysplasia, arrhythmogenic right ventricular cardiomyopathy, and arrhythmogenic ventricular cardiomyopathy. The disease is associated with sudden death in youths, particularly during exercise. A century ago, in the time of Osler, there were references to parchment heart, possibly the same entity. Another entity, Uhl’s anomaly, may also be related but is usually found in an infant or young child with congestive heart failure rather than in cases of sudden death. Pathological findings include a thin right ventricular wall which transilluminates well and fibrofatty replacement of myocardium, especially prominent in, but not limited to, the right ventricle. Many cases are familial with peak onset at ages 16-35 years. The pattern of inheritance is autosomal dominant.

Arrhythmogenic cardiomyopathy (ACM)

This trichrome-stained section from the left ventricle of the patient in the previous slide shows fibrosis. ACM has been called arrhymogenic right ventricular dysplasia, however, fatty or fibrous replacement of the myocardium can often be seen in any portion of the heart. Foci of lymphocytic myocarditis can also be present.

There are many synonyms for this entity including arrhythmogenic right ventricular dysplasia, arrhythmogenic ventricular dysplasia, arrhythmogenic right ventricular cardiomyopathy, and arrhythmogenic ventricular cardiomyopathy. The disease is associated with sudden death in youths, particularly during exercise. A century ago, in the time of Osler, there were references to parchment heart, possibly the same entity. Another entity, Uhl’s anomaly, may also be related but is usually found in an infant or young child with congestive heart failure rather than in cases of sudden death. Pathological findings include a thin right ventricular wall which transilluminates well and fibrofatty replacement of myocardium, especially prominent in, but not limited to, the right ventricle. Many cases are familial with peak onset at ages 16-35 years. The pattern of inheritance is autosomal dominant.