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Hamartoma of mature cardiac myocytes
A P Burke1, J K Ribe, A K Bajaj
1Department of Cardiovascular Pathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000, USA.
Insights
Cardiac myocyte hamartomas, a novel tumor, present features similar to hypertrophic cardiomyopathy. These distinct, unencapsulated masses are a newly identified cardiac entity.
Area of Science:
- Cardiovascular Pathology
- Cardiac Oncology
- Tumor Biology
Background:
- Hypertrophic cardiomyopathy (HCM) is characterized by cardiac hypertrophy, myofiber disarray, and intramural coronary thickening.
- Localized cardiac tumors are rare, with no prior reports of hamartomas composed of mature cardiac myocytes outside the typical HCM locations.
- Understanding rare cardiac tumors is crucial for accurate diagnosis and patient management.
Observation:
- Three patients (ages 9, 22, 28) presented with localized hamartomas of mature cardiac myocytes.
- Clinical presentations varied, including cardiac arrhythmias, sudden death, Wolff-Parkinson-White syndrome, and asymptomatic cases.
- Pathological examination revealed discrete, unencapsulated nodules of hypertrophied myocytes with disorganization, scarring, and thickened intramural arteries.
Findings:
- The hamartomas were distinct from hypertrophic cardiomyopathy and cardiac rhabdomyoma, lacking septal asymmetry and myocyte vacuolization.
- Histology showed marked myocyte hypertrophy, disorganization, focal scarring, and thickened intramural arteries.
- Ultrastructural analysis revealed abundant, disorganized myofilaments with normal intercellular junctions.
Implications:
- Cardiac myocyte hamartoma is a newly described cardiac tumor.
- This entity shares features with hypertrophic cardiomyopathy and rhabdomyoma but is considered separate.
- Further research is needed to elucidate the pathogenesis and clinical significance of cardiac myocyte hamartomas.
Abstract:
The clinical and pathological findings of three patients with hamartomas of mature cardiac myocytes resembling localized hypertrophic cardiomyopathy are presented. Hypertrophic cardiomyopathy is manifest by a poorly demarcated area of cardiac hypertrophy, microscopically demonstrating myofiber disarray and intramural coronary thickening. Localized, nonencapsulated masses of hypertrophied cardiac myocytes in locations other than the left ventricle or ventricular septum have not been reported. The clinical and pathological data of three patients with localized hamartomas were retrospectively retrieved. The patients were 9, 22, and 28 years old, respectively; none had a known family history of heart disease or cardiomyopathy. Two patients had cardiac arrhythmias: one patient died suddenly, and one patient had the Wolff-Parkinson-White syndrome. The third patient was asymptomatic. Two patients treated surgically had single masses in the right atrium and right ventricle, respectively. The patient who died suddenly had multiple discrete masses throughout the atrial and ventricular myocardium, including the left ventricular free wall. None of the three patients had septal asymmetry suggestive of hypertrophic cardiomyopathy. Histologically, there were discrete but unencapsulated nodules of marked myocyte hypertrophy with disorganization, focal scarring, and thickened intramural arteries. There was no myocyte vacuolization suggestive of cardiac rhabdomyoma. Ultrastructurally, the myocytes showed abundant and disorganized myofilaments and normal intercellular junctions. Hamartoma of mature cardiac myocytes is a previously undescribed cardiac tumor that shares some features of hypertrophic cardiomyopathy and rhabdomyoma, but is currently best considered a separate entity.