Infantile histiocytoid cardiomyopathy--myocardial or conduction system hamartoma: what is the cell type involved?

Histiocytoid cardiomyopathy presenting as sudden death in an 18-month-old infant

Histiocytoid cardiomyopathy (HC) is an arrhythmogenic disorder, usually involving children under two years of age with a strong Caucasian and female predominance. The disease is fatal in the vast majority and diagnosis is nearly always established at autopsy, but this is only possible with adequate myocardial sampling. Meticulous gross and histological examination of the heart in collaboration with a cardiovascular-trained pathologist maximises the opportunity to make specific diagnoses (and therefore rule out the differentials of SIDS, SUDC and child abuse), guide genetic testing, and inform potentially life-saving medical interventions for blood relations. We present a typical HC case presenting as sudden death, without prodrome, in a previously healthy 18-month-old boy. The disease is characterised histologically by discrete groups of enlarged, polygonal histiocyte-like cells with distinct margins and abundant faintly eosinophilic foamy cytoplasm. Cells often contain coarse granules, microvacuoles and irregular, round nuclei. In our case, dysplastic fascicles were predominantly located immediately deep to the endocardium of the left ventricle. We report our own autopsy findings with histological images, and discuss the expected clinical, morphological and ultrastructural features of the disease.

2019 HRS expert consensus statement on evaluation, risk stratification, and management of arrhythmogenic cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is an arrhythmogenic disorder of the myocardium not secondary to ischemic, hypertensive, or valvular heart disease. ACM incorporates a broad spectrum of genetic, systemic, infectious, and inflammatory disorders. This designation includes, but is not limited to, arrhythmogenic right/left ventricular cardiomyopathy, cardiac amyloidosis, sarcoidosis, Chagas disease, and left ventricular noncompaction. The ACM phenotype overlaps with other cardiomyopathies, particularly dilated cardiomyopathy with arrhythmia presentation that may be associated with ventricular dilatation and/or impaired systolic function. This expert consensus statement provides the clinician with guidance on evaluation and management of ACM and includes clinically relevant information on genetics and disease mechanisms. PICO questions were utilized to evaluate contemporary evidence and provide clinical guidance related to exercise in arrhythmogenic right ventricular cardiomyopathy. Recommendations were developed and approved by an expert writing group, after a systematic literature search with evidence tables, and discussion of their own clinical experience, to present the current knowledge in the field. Each recommendation is presented using the Class of Recommendation and Level of Evidence system formulated by the American College of Cardiology and the American Heart Association and is accompanied by references and explanatory text to provide essential context. The ongoing recognition of the genetic basis of ACM provides the opportunity to examine the diverse triggers and potential common pathway for the development of disease and arrhythmia.

Arrhythmia-Induced Cardiomyopathies: Mechanisms, Recognition, and Management

Arrhythmia-induced cardiomyopathy (AIC) is a potentially reversible condition in which left ventricular dysfunction is induced or mediated by atrial or ventricular arrhythmias. Cellular and extracellular changes in response to the culprit arrhythmia have been identified, but specific pathophysiological mechanisms remain unclear. Early recognition of AIC and prompt treatment of the culprit arrhythmia using pharmacological or ablative techniques result in symptom resolution and recovery of ventricular function. Although cardiomyopathy in response to an arrhythmia may take months to years to develop, recurrent arrhythmia can result in rapid decline in ventricular function with development of heart failure, suggesting residual ultrastructural abnormalities. Reports of sudden death in patients with normalized left ventricular ejection fraction cast doubt on the complete reversibility of this condition. Several aspects of AIC, including specific pathophysiological mechanisms, predisposing factors, optimal therapeutic strategies to prevent ultrastructural changes, and long-term risk of sudden death remain unresolved and need further research.

Exome sequencing of patients with histiocytoid cardiomyopathy reveals a de novo NDUFB11 mutation that plays a role in the pathogenesis of histiocytoid cardiomyopathy

Histiocytoid cardiomyopathy (Histiocytoid CM) is a rare form of cardiomyopathy observed predominantly in newborn females that is fatal unless treated early in life. We have performed whole exome sequencing on five parent-proband trios and identified nuclear-encoded mitochondrial protein mutations in three cases. The molecular genetic basis of Histiocytoid CM remains unknown despite several hypotheses in medical literature. The findings presented in this manuscript may represent components of genetic etiologies for this heterogeneous disease. Two probands had de novo non-sense mutations in the second exon of the X-linked nuclear gene NDUFB11. A third proband was doubly heterozygous for inherited rare variants in additional components of complex I, NDUFAF2 and NDUFB9, confirming that Histiocytoid CM is genetically heterogeneous. In a fourth case, the proband with Histiocytoid CM inherited a mitochondrial mutation from her heteroplasmic mother, as did her brother who presented with cardiac arrhythmia. Strong candidate recessive or compound heterozygous variants were not found for this individual or for the fifth case. Although NDUFB11 has not been implicated before in cardiac pathology, morpholino-mediated knockdown of ndufb11 in zebrafish embryos generated defective cardiac tissue with cardiomegaly, looping defects, and arrhythmia which suggests the role of NDUFB11 in the pathogenesis of this abnormal cardiac pathology. Taken together, the unbiased whole exome sequencing approach confirms the suspected genetic heterogeneity of Histiocytoid CM. Therefore, the novel NDUFB11 mutation may cause a complex 1 deficiency in synergy with additional unknown mtDNA variants.

2011 consensus statement on endomyocardial biopsy from the Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology

The Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology have produced this position paper concerning the current role of endomyocardial biopsy (EMB) for the diagnosis of cardiac diseases and its contribution to patient management, focusing on pathological issues, with these aims: • Determining appropriate EMB use in the context of current diagnostic strategies for cardiac diseases and providing recommendations for its rational utilization • Providing standard criteria and guidance for appropriate tissue triage and pathological analysis • Promoting a team approach to EMB use, integrating the competences of pathologists, clinicians, and imagers.

Histiocytoid cardiomyopathy: a mitochondrial disorder

Histiocytoid cardiomyopathy (HICMP) is a rare, genetic, cardiac disorder of infancy or childhood, predominantly affecting girls, and clinically manifesting as severe cardiac arrhythmias or dilated cardiomyopathy. Pathoanatomically, HICMP is characterized by subendocardial, epicardial, or valvular yellow-tan nodules, which are histologically built up of abnormal Purkinje fibers and multiple, scattered clusters of histiocytoid myocytes, which are filled with an increased number of normal or abnormal mitochondria. Within the myocardium, yellowish areas with irregular outlines are found and are histologically built up of enlarged, polygonal, histiocyte-like cells with foamy granular cytoplasm. Since HICMP is frequently found in patients with mitochondrial deoxyribonucleic acid (DNA) mutations, HICMP cardiomyocytes carry an increased number of normal or abnormal mitochondria, and may show markedly decreased succinate-cytochrome c reductase or NADH-cytochrome c reductase activity; HICMP should be regarded as mitochondrial cardiomyopathy.

Cardiac tumours in children

Cardiac tumours are benign or malignant neoplasms arising primarily in the inner lining, muscle layer, or the surrounding pericardium of the heart. They can be primary or metastatic. Primary cardiac tumours are rare in paediatric practice with a prevalence of 0.0017 to 0.28 in autopsy series. In contrast, the incidence of cardiac tumours during foetal life has been reported to be approximately 0.14%. The vast majority of primary cardiac tumours in children are benign, whilst approximately 10% are malignant. Secondary malignant tumours are 10-20 times more prevalent than primary malignant tumours. Rhabdomyoma is the most common cardiac tumour during foetal life and childhood. It accounts for more than 60% of all primary cardiac tumours. The frequency and type of cardiac tumours in adults differ from those in children with 75% being benign and 25% being malignant. Myxomas are the most common primary tumours in adults constituting 40% of benign tumours. Sarcomas make up 75% of malignant cardiac masses. Echocardiography, Computing Tomography (CT) and Magnetic Resonance Imaging (MRI) of the heart are the main non-invasive diagnostic tools. Cardiac catheterisation is seldom necessary. Tumour biopsy with histological assessment remains the gold standard for confirmation of the diagnosis. Surgical resection of primary cardiac tumours should be considered to relieve symptoms and mechanical obstruction to blood flow. The outcome of surgical resection in symptomatic, non-myxomatous benign cardiac tumours is favourable. Patients with primary cardiac malignancies may benefit from palliative surgery but this approach should not be recommended for patients with metastatic cardiac tumours. Surgery, chemotherapy and radiotherapy may prolong survival. The prognosis for malignant primary cardiac tumours is generally extremely poor.

Tumors associated with sudden infant and childhood death

Tumors are rare causes of sudden death in infancy and early childhood. The goals of this study were to determine the types and frequency of the tumors associated with sudden death occurring in cases between birth and age 3 years. The San Diego Sudden Infant Death Syndrome/sudden unexplained death in childhood (SUDC) Research Project database and the literature were reviewed retrospectively. Sixty-eight cases, with the most (84%) affecting the heart and brain, were identified. Tumors are a rare but significant cause of sudden death in infancy and early childhood, and their diagnosis may have significant genetic implications for planning future pregnancies. The diagnosis of these lesions can be established only after thorough postmortem examination.

Fetal and neonatal cardiac tumors

Primary tumors of the heart are uncommon in the fetus and neonate. Nevertheless, the widespread use of new imaging techniques has contributed significantly to earlier diagnosis, treatment, and thus improved survival. The clinical findings, imaging studies, pathology, and outcome of 224 fetuses and neonates with cardiac tumors collected from the literature are evaluated and discussed. Most tumors are benign, and of these rhabdomyoma is the most common, followed by teratoma, fibroma, oncocytic cardiomyopathy, vascular tumors, and myxoma. Malignant and metastatic tumors are described but are rare. Murmurs, arrhythmias, cyanosis, respiratory distress, and cardiac failure are the main presenting signs of cardiac tumors in the perinatal period. Disturbances in hemodynamic function are correlated with the size and location of the tumor. Cardiac vascular tumors have the best outcome, whereas malignant tumors have the worst. The purpose of this review is to concentrate on the fetus and neonate in an attempt to determine the various ways cardiac tumors differ clinically and morphologically in this age group from those occurring in older children and adults and to show that certain types of tumors have a better prognosis than others.

Demonstration of MyoD1 expression in oncocytic cardiomyopathy: report of two cases and review of the literature

Oncocytic cardiomyopathy is a rare arrhythmogenic disorder usually associated with female sex, difficult-to-control arrhythmias, or sudden death of infants and children. Morphologically, it is characterized by the presence of oncocytic cells, which are diffusely distributed or form the nodular structures within the myocardium, occasionally involving the valves, with a large number of mitochondria in cytoplasms. We present two cases of oncocytic cardiomyopathy. The first case had a fatal clinical outcome, and the other case was surgically treated. The nuclear expression of skeletal muscle transcription factor MyoD1 was demonstrated in the first case, supporting the theory that oncocytic cardiomyopathy is a conduction system developmental disorder. To confirm this hypothesis, it is necessary to further investigate myogenic transcription factor program in human cardiac conduction system cells.

Cardiac pathology in sudden unexpected infant death

OBJECTIVES

To determine the spectrum of cardiac pathology and circumstances of death in infants with sudden unexpected death and to define the impact of sudden cardiac deaths to overall sudden infant death.

STUDY DESIGN

Retrospective analysis of all autopsies of infants with sudden death 7 days to 2 years of age between January 1987 and December 1999 in the province of Québec (Canada).

RESULTS

Eighty-two cases of sudden death with cardiac pathology were found, representing 10% of the total number of sudden infant deaths. A structural malformation was present in the majority of cases (54%); however, cardiac pathology in anatomically normal hearts was also common (46%). Most (64%) anatomic malformations were detected before death compared with 13% of nonstructural heart disease. Although a major proportion of children were found dead during sleep, a significant number were described as being awake at time of death (32%).

CONCLUSIONS

Heart disease is present in a significant percentage of autopsies of infants with sudden death. Structural heart malformations predominate, although nonstructural pathologic features of the heart are common and usually unrecognized before an autopsy is performed. Cardiac pathologic features are frequent when the child is witnessed to be awake at the time of sudden death.

A missense mutation in the mitochondrial cytochrome b gene in a revisited case with histiocytoid cardiomyopathy

We describe a pathogenic mutation in the mitochondrial cytochrome b gene in a patient with a multisystem disorder presenting as histiocytoid cardiomyopathy in whom a defect of ubiquinol cytochrome c oxidoreductase of the electron transport chain had been documented biochemically. The mutation, a G to A transition at nucleotide 15498, results in the substitution of glycine with aspartic acid at amino acid position 251. The mutation, which is heteroplasmic and fulfills all accepted criteria for pathogenicity, is likely to impair the function of the holoenzyme as deduced from its effects on the crystal structure of ubiquinol cytochrome c oxidoreductase. This is the first molecular defect associated with histiocytoid cardiomyopathy.

Histiocytoid cardiomyopathy: three new cases and a review of the literature

Histiocytoid cardiomyopathy (HC), a rare arrhythmogenic disorder, presents as difficult-to-control arrhythmias or sudden death in infants and children, particularly girls. Three cases are described with autopsy findings. In two cases, yellow-tan nodules were grossly visible in the myocardium; in the third case, no gross lesions were identified. Microscopic examination in all three cases revealed multiple, scattered clusters of histiocytoid myocytes which on ultrastructural examination were filled with abnormal mitochondria, scattered lipid droplets, and scanty myofibrils. These pathologic findings are similar to those previously described. The pathogenesis of this entity remains controversial. It was recently proposed that this disorder is X-linked dominant with the associated gene located in the region of Xp22.

Histiocytoid cardiomyopathy: a cause of sudden death in infancy

We report the case of an infant aged of 14 months deceased of sudden death. The diagnosis of histiocytoid cardiomyopathy was made on a necropsic basis. The pathologic examination showed a cardiac hypertrophy characterized by yellowish areas with irregular outlines, disseminated in the myocardium, and made of histiocyte-like cells with foamy or granular cytoplasm. These cells reacted positively with desmin and myoglobin labels, and had rare and disorganised myofibrils in electron microscopy, proving their muscular origin. The illness affects infants and usually causes severe cardiac troubles leading to death without treatment. This case is the fourteenth associated with sudden death.

Unexpected death in two young infants mimics SIDS: autopsies demonstrate tumors of medulla and heart

A total of 423 medicolegal autopsies of infants under the age of 1 year were done during a 15-year period (1980-1994) at the Department of Forensic Medicine in Stockholm. Only two instances with findings of tumors occurred. One was a unilateral oligodendroglioma involving the medullary reticular formation and inferior olivary nucleus with associated myocardial alterations; the other was a fibroma of the left heart ventricle. Both are interesting with regard to their localization--the medulla oblongata and the heart--and by causing death in a way that mimics the sudden infant death syndrome (SIDS). In the heart of the infant with oligodendroglioma, a single fascicle of hamartomatous, immature appearing heart muscle fibers was found, making the interpretation of the cause of death more intricate.

Oncocytic cardiomyopathy: a rare cause of unexpected early childhood death associated with fitting

A 15-month-old girl died unexpectedly in hospital following a five-day history of intermittent cardiac arrhythmias and convulsions preceded by several weeks of occasional vomiting. Autopsy revealed subendocardial nodules in the left ventricle, and tricuspid and mitral valves that were composed of aggregated large cells with foamy, pale pink cytoplasm characteristic of oncocytic cardiomyopathy. Fat stains were positive for neutral lipid and phospholipid and electron microscopic examination revealed numerous irregular mitochondria within affected cells. Examination of the brain revealed no structural or histologic abnormalities, anoxic damage or thromboembolic material. Oncocytic cardiomyopathy, though rare, may cause unexpected death in previously well young children with quite variable preceding clinical symptoms and signs which include fitting. Although the aetiology is unknown there is evidence that mitochondrial dysfunction may be involved.

Histiocytoid cardiomyopathy and sudden death

We present a case of histiocytoid cardiomyopathy resulting in sudden and unexpected death in a 4-month-old infant with Peter's Anomaly and congenital glaucoma. At autopsy, the granular histiocytoid cells that define this entity were found predominantly involving the conduction system, with encasement and partial replacement the His' Bundle. Large aggregates of these cells formed atrioventricular and nodoventricular connections, indicating a possible mechanism for the arrhythmias characteristic of the condition. The striking propensity for involvement of the conduction system in this case lends further support to the view that this disorder represents a developmental anomaly of the Purkinje cell system of the heart.

Histiocytoid cardiomyopathy with hypotonia in an infant

A 15 month old female, who had suffered from ventricular tachycardia from the prenatal period, experienced cardiac arrest at home. Once she had recovered, ventricular tachycardia occurred repeatedly. She died 7 months after admission. At autopsy, the heart showed many yellowish white nodules in the endocardium. Histologically these nodules consisted of granular or foamy histiocyte-like cells, which had spread to all four chambers. Electron micrographs showed mitochondrial hyperplasia in these cells. The cells had some myofibrils in their cytoplasm. These findings were compatible with histiocytoid cardiomyopathy. Interestingly, the present case showed hypotonia. Her muscle biopsy revealed decreased activity of cytochrome c oxidase, suggesting that histiocytoid cardiomyopathy is related to mitochondrial cytopathy.

[Heart and sudden infant death. Anatomopathological study of 100 cases]

BACKGROUND

Post-mortem examination of infants with sudden infant death syndrome (SIDS) is essential for understanding the cause and/or mechanism of death. This study aims to evaluate the contributions of heart in SIDS.

POPULATION AND METHODS

Between 1981 and 1990, the CHU of Nantes carried out autopsies on 162 cases of sudden infant death syndrome. One hundred files were accepted for this retrospective study because a second recent macroscopic and microscopic (11 samples for each heart) examination of heart was possible.

RESULTS

The weight of hearts was not increased, except in one case. Macroscopic examination did not reveal any cardiac abnormalities. Histological examination confirmed the lesions initially observed in 11 cases and probably responsible for their death.

CONCLUSIONS

This study underlines the importance of studying numerous samples of each heart of microscopic examination of many sections.

Female infant with oncocytic cardiomyopathy and microphthalmia with linear skin defects (MLS): a clue to the pathogenesis of oncocytic cardiomyopathy?

A infant girl had red stellate skin lesions on the cheeks and neck, and mildly short palpebral fissures. Her skin abnormality was typical of microphthalmia with linear skin defects (MLS), a newly recognized syndrome consisting of congenital linear skin defects and ocular abnormalities in females monosomic for Xp22. She died suddenly and unexpectedly at age 4 months; the cause of death was ascribed to oncocytic cardiomyopathy. Oncocytic cardiomyopathy occurs only in young children, who present with refractory arrhythmias leading to cardiac arrest. The coexistence of two rare conditions, one of which is mapped to the X chromosome, and an excess of affected females with oncocytic cardiomyopathy, make it likely that oncocytic cardiomyopathy is also X-linked, with Xp22 being a candidate region. Overlapping manifestations in the two conditions (ocular abnormalities in cases of oncocytic cardiomyopathy and arrhythmias in MLS) offer additional support for this hypothesis.