Histiocytoid cardiomyopathy in infancy: a new hypothesis?

Histiocytoid cardiomyopathy and ventricular non-compaction in a case of sudden death in a female infant

A case of sudden infant death with histiocytoid cardiomyopathy and ventricular non-compaction was investigated with immunohistochemical methods. Histiocytoid cardiomyopathy is thought to be a developmental defect of the cardiomyocytes of the conduction system. In contrast to mature cardiomyocytes, the histiocytoid cells showed only weak reactions to desmin and myosin antibodies. They lacked cross-striation but reacted strongly to enolase and myoglobin antibodies. The protein Pax-7, seen only in cells undergoing differentiation, and the proliferation marker Ki-67 were not expressed in the histiocytoid cells. In areas of altered myocardium, clusters of CD4-, CD8-, and CD68-positive inflammatory cells were seen as well an abundance of mast cells. With the TUNEL method, it was found that many of the histiocytoid cells were undergoing apoptosis. Our results confirm that the histiocytoid cells are defective cardiomyocytes. The apoptotic and inflammatory changes point to a degenerative process rather than defective maturation of cardiomyocytes as has been suggested in some earlier studies. Ventricular non-compaction is a developmental defect of the subendocardial tissue with hypertrabeculation and weak development of the papillary muscles. Only one case combined with histiocytoid cardiomyopathy has been described previously. A causal connection between the two conditions cannot be established until more cases have been analyzed.

Orthotopic heart transplantation in a child with histiocytoid cardiomyopathy

We report a case of histiocytoid cardiomyopathy in a 30-month-old child. This rare disorder has been identified in <100 patients worldwide and no previous reports of cardiac transplantation with this condition have been identified. We reviewed the clinical and pathologic findings and compared them to previous studies.

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.

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.

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.

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.

Infantile histiocytoid cardiomyopathy: three cases and literature review

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.

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

Primary myocardial diseases in the pediatric age group encompass a variety of metabolic, infectious, congenital, and acquired disorders, one of which is "histiocytoid cardiomyopathy." We describe clinical and pathologic features in two infants. Autopsy findings in the first case were consistent with sudden cardiac death. The second infant has survived for 2 years on antiarrhythmic therapy with amiodarone. Microscopically, cells with vacuolated to granular cytoplasm were grouped in fascicles, imparting a pseudonodular appearance, but following a distribution reminiscent of conduction fibers. Ultrastructurally, the cells lack a T-tubule system, possess scattered lipid droplets and desmosomes rather than side-to-side junctions, and contain leptomeric fibrils that predominantly marginate to the cell periphery without sarcomeres. Immunostaining of paraffin-embedded tissue reveals perimembranous immunoreactivity for muscle-specific actin, but not for the histiocytic markers CD68 (KP1) and lysozyme. Immunohistochemistry may be a practical alternative when tissue is not saved for electron microscopy. The clinical and pathologic features of this disorder in light of the current literature suggest that it may be hamartoma, possibly of conduction system origin.

Diethylene glycol (DEG)-associated myocardial changes: a pilot investigation of chronic intoxication in guinea-pigs

The myocardium of guinea pigs fed on sublethal doses of diethylene glycol (DEG) over a period of 2-11 days was examined for microscopical and ultrastructural changes. Coagulative myocytolysis and loss of myofibrils, not observed in the controls, was patchily distributed throughout the myocardium. The accompanying ultrastructural features included swelling, pleomorphism and hyperplasia of mitochondria with an associated distension of the interfibrillary spaces and a displacement, distortion and rupture of adjacent myofibrils.

Unexpected infant death attributable to cardiac tumor or cardiomyopathy. Immunohistochemical and electron microscopical findings in three cases

The pathological findings, including immunohistochemical and electron microscopical findings, in three infants who died unexpectedly of cardiac tumor or cardiomyopathy are reported. The first was a 13-month-old boy with tuberous sclerosis and multiple rhabdomyomas of the heart, who presented with a postpartal cardiac murmur and moderate cardiomegaly. The further history was unknown. The rhabdomyoma nodules were composed of spider cells containing small amounts of desmin and myosin as well as isolated myofibrils. Microscopically small glioma nodules contained high amounts of GFAP. The second case, a boy 4 months of age, died of a large benign fibrous histiocytoma of the heart after an uneventful history. Tumor cells contained alpha-1-anti-chymotrypsin and lysozyme. The third case, a girl 2 months of age, died unexpectedly of histiocytoid cardiomyopathy. The affected cells contained fat droplets, glycogen granules, many leptomer myofibrils and small amounts of myosin and desmin.

Incessant ventricular tachycardia in infancy

Two infants with incessant tachycardia uncontrolled by multiple drug treatment were thought initially to have supraventricular tachycardia. Careful examination of the 12-lead electrocardiogram suggested ventricular tachycardia, which was confirmed by electrophysiological studies. Intra-operative mapping showed that the arrhythmia arose from the posterior left ventricular free wall in one infant and at the left ventricular apex in the other. Cryoablation of these foci led to cessation of ventricular tachycardia. Myocardial biopsy showed hamartomatous involvement in the first infant and normal tissue in the other. In the first infant the incessant arrhythmia was cured but in the other it recurred 4 months later. The origin of the recurrent tachycardia was adjacent to the previously cryoablated arrhythmogenic area. This area was also cryoablated, leading to disappearance of the ventricular tachycardia. Both patients are free of arrhythmia 10 months and 3 months after their surgery. Surgically ablatable lesions are common in infants with incessant ventricular tachycardia. Early diagnosis and prompt surgical treatment usually can effect 'cure' of this potentially fatal problem in childhood.

Oncocytic cardiomyopathy of infancy with Wolff-Parkinson-White syndrome and ectopic foci causing tachydysrhythmias in children

Two female infants, ages 6 months and 13 months, were first seen in the newborn period with supraventricular tachycardia associated with Wolff-Parkinson-White syndrome. One infant had echocardiographic and angiographic evidence of diffuse cardiomyopathy and died suddenly at home. The other infant was seen initially at 13 months of age with refractory ventricular tachycardia and died following surgical resection of arrhythmogenic foci on the left and right ventricles. Autopsy showed diffuse patchy oncocytic cardiomyopathy in both instances. Serial histologic sections of the cardiac conduction system showed oncocytic involvement of the atrioventricular (AV) node, His bundle, and bundle branches. Both infants had interruption of the anulus fibrosus by oncocytic cells at several sites, resulting in multiple accessory AV and nodoventricular connections. Additionally, patient No. 1 had an accessory AV connection by oncocytic cells in the fatty fibrous tissue of the left AV sulcus. To our knowledge, this is the first report of multiple accessory AV connections of oncocytic cells seen during histologic study. In addition, both infants had oncocytic involvement of the exocrine and endocrine glands. This report discusses the clinicopathologic correlations in these two patients, the literature on oncocytic cardiomyopathy, and the types of dysrhythmias found in these patients and their management.

Incessant ventricular tachycardia in infants: myocardial hamartomas and surgical cure

Infants with incessant ventricular tachycardia (occurring greater than 10% of the day) have generally been described in pathologic studies. This report describes 21 patients with incessant ventricular tachycardia present greater than 90% of the day and night; the age at diagnosis ranged from birth to 30 months (mean 10.5 months). The most common clinical presentation was cardiac arrest (11 patients, in 5 after digitalis for presumed supraventricular tachycardia); another 6 patients had congestive heart failure and 4 were asymptomatic. Three patients had coexisting Wolff-Parkinson-White syndrome. The rate of incessant ventricular tachycardia ranged from 167 to 440 (mean 260 beats/min) and the QRS duration from 0.06 to 0.11 second. The most common electrocardiographic (ECG) pattern (10 of 21) was right bundle branch block with left axis deviation, but other right and left bundle branch block patterns were observed. Conventional and investigational antiarrhythmic agents (nine patients received amiodarone) failed to eliminate incessant ventricular tachycardia in all. Electrophysiologic studies localized incessant ventricular tachycardia to the left ventricle in 17 (to the apex in 2, the free wall in 9 and the septum in 6) and to the right ventricular septum in 4. No structural abnormalities were found on the echocardiogram or angiocardiogram. All 21 patients had surgery at an age of 3.5 to 31 months (mean 16). In 15 a tumor was found: 13 myocardial hamartomas (9 discrete, 4 diffuse throughout both ventricles) and 2 rhabdomyomas (1 multiple). Myocarditis was found in one patient (the oldest). In four, only myocardial fibrosis was found; results of one biopsy were normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Pathologic features of myocardial hamartomas causing childhood tachyarrhythmias

We have observed in 11 infants, aged 2 years or less, a distinct clinicopathologic lesion responsible for tachyarrhythmias that were fatal in 96% (25/26) of previously reported cases. Nine of the 11 patients, who underwent electrophysiologic mapping and surgical excision of the lesion, have survived, with follow-up periods ranging from 1 month to 6 years. The morphologic findings in these 11 patients and in the 26 cases cited in the literature are reviewed. Pathogenic considerations have included viral-induced lesion, cardiomyopathy, neoplasm, and developmental disorder of Purkinje cells. We believe this lesion to be a myocardial hamartoma. Supportive evidence includes prevalence in infants, tumorlike growth pattern without mitotic figures, and association of other developmental abnormalities. Through electrophysiologic mapping, this myocardial hamartoma is potentially accessible to surgical excision and long-term cure.

Foamy myocardial transformation of infancy: an inherited disease

Five cases of foamy myocardial transformation of infancy, a condition which predominantly affects female children under 2 years of age and which causes cardiac arrhythmia or sudden death, are reported. Of these five cases, four occurred in two sets of siblings, suggesting a possible hereditary basis for the disease. As far as we know, no other familial cases have been reported. The other case was of focal disease of the myocardium, as opposed to the diffuse myocardial changes seen in the four familial cases.

Fatal mitochondrial cardiomyopathy in Kearns-Sayre syndrome

The clinical and postmortem findings in a 26 year old man with Kearns-Sayre syndrome are described. In the last years of his life he suffered from cardiac arrhythmias and a congestive cardiomyopathy, dying of cardiac pump failure. The heart was enlarged, especially the left ventricle which was fibrotic and excessively dilated. Histological and fine structural investigation revealed an excessive loss of myofibrils and an increase of enlarged mitochondria with lamellar and atypically tubular cristae in widespread heart muscle cells. Mitochondrial anomalies were also observed in some cells of the conductive system. This patient thus suffered not only from a mitochondrial myopathy with ragged red fibers but also from a fatal mitochondrial cardiomyopathy. The anomalies observed in the mitochondria of the conductive system cells suggest that the well-known conductive abnormalities in patients with Kearns-Sayre syndrome might be at least partly caused by disturbed function of these mitochondria.

A case of foamy myocardial transformation of infancy

A case of infantile cardiomyopathy in a year and four months old girl, which was clinically characterized by tachycardia resistant to any drugs and marked hyperplasia of mitochondria in their cytoplasms on electron microscopic observation, was presented. In the present case light and electron microscopical proof of the diagnosis was obtained by right endomyocardial biopsy, while most of this condition has not been recognized prior to autopsy. In Japan this newly recognized infantile cardiomyopathy has not been reported, and we proposed that this condition could be designated as mitochondrial cardiomyopathy caused by unknown etiology. The literatures described previously in the world have been reviewed.

Congenital "histiocytoid" cardiomyopathy: evidence suggesting a developmental disorder of the Purkinje cell system of the heart

The so-called "histiocytoid cardiomyopathy" is an unusual cardiac disorder of infancy and childhood, characterized by the presence of numerous foamy, lipid-containing cells between the endocardium and the striated myocardial cells of the left ventricle and the interventricular septum. The disease usually affects females, the clinical picture being dominated by severe disturbances of conduction. The original designations of the disorder stem from the morphological resemblance of the foamy cells to lipid-laden histiocytes. However, subsequent investigations have shown these cells to contain myofibrils interposed with Z lines. It has, therefore, been suspected that the leading cell population might be related to the myocardium. Using a histochemical method for the demonstration of cholinesterase activity in the foamy cells, we present evidence that "histiocytoid" cardiomyopathy may in fact correspond to a maldevelopment of the Purkinje cell system of the heart.

Oncocytic cardiomyopathy in an infant with oncocytosis in exocrine and endocrine glands

An 11 week old female infant with congenitally malformed eyes died from intractable cardiac arrhythmia. The heart showed extensive oncocytic transformation of myocytes, and this distinctive cardiomyopathy affected the conduction system. Oncocytes were found also in endocrine (pituitary, thyroid) and exocrine (submandibular, sublingual, minor salivary) glands. There is morphologic evidence that the lesions were caused early in gestation, possibly by a viral infection such as rubella.