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Infantile histiocytoid cardiomyopathy: three cases and literature review
V Malhotra1, V J Ferrans, R Virmani
1Department of Cardiovascular Pathology, Armed Forces Institute of Pathology, Washington, DC.
Insights
Histiocytoid cardiomyopathy, a rare infant heart condition, involves abnormal myocytes causing fatal arrhythmias. This review details its clinical and cardiac findings, suggesting prenatal injury as a cause.
Area of Science:
- Cardiology
- Pediatric Pathology
- Mitochondrial Biology
Background:
- Histiocytoid cardiomyopathy is a rare cardiac disorder affecting infants and children.
- It is characterized by severe arrhythmias and distinctive cardiac morphologic findings.
Observation:
- The study reviews 53 patients (50 reported, 3 new) with histiocytoid cardiomyopathy.
- Morphologically, affected myocytes are round, lack intercellular junctions, have few contractile elements, and abundant mitochondria.
- Associated anomalies include nervous system and eye abnormalities, and oncocytic cells in glands.
Findings:
- Histiocytoid cardiomyopathy presents with focal collections of abnormal myocytes, sometimes forming yellowish nodules on cardiac structures.
- These myocytes exhibit features similar to oncocytes, suggesting hamartoma-like aggregations.
- The condition is differentiated from developmental anomalies, tumors, and diffuse mitochondrial cardiomyopathies.
Implications:
- The syndrome is hypothesized to result from prenatal myocardial or systemic injury.
- Surgical excision of histiocytoid cell nodules may lead to clinical remission.
- Understanding the etiology is crucial for diagnosis and potential therapeutic strategies in pediatric cardiology.
Abstract:
A review is presented of the clinical and cardiac morphologic findings in 50 previously reported and 3 new patients with histiocytoid cardiomyopathy. This disorder occurs in infants and small children and is characterized clinically by severe and often fatal arrhythmias and morphologically by focal collections of altered myocytes that are roundshaped and resemble histiocytes. Sixteen patients had yellowish nodules on the endocardium, epicardium, and/or valves; the other 37 had foci of abnormal myocytes throughout the myocardium. These cells were remarkably similar in all patients and had poorly developed or absent intercellular junctions, few or no contractile elements, and markedly increased numbers of mitochondria, which imparted a granular or vacuolated appearance to the cytoplasm. There was a high prevalence of anomalies involving the nervous system and eyes and of oncocytic cells in various glands. Evidence is presented to exclude the possibilities that the disorder represents a developmental anomaly of the atrioventricular conduction system, a multifocal tumor of Purkinje cells, a developmental arrest of cardiac myocytes, and a diffuse type of mitochondrial cardiomyopathy. Histiocytoid cardiomyopathy is considered to be the result of hamartoma-like aggregations of cardiac myocytes with features similar to those of oncocytes. This syndrome is likely caused by prenatal myocardial or systemic (viral?) injury. Surgical excision of nodules of histiocytoid cells can result in clinical remission.