European Journal of Echocardiography Advance Access published online on June 20, 2008
European Journal of Echocardiography, doi:10.1093/ejechocard/jen182
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2008. For permissions please email: journals.permissions@oxfordjournals.org
Hamartomas of mature cardiac myocytes
Shaji C. Menon1,*,
Dylan V. Miller2,
Allison K. Cabalka1 and
Donald J. Hagler1
1 Pediatric Cardiology, Mayo Clinic, 200 First Street SW, Gonda 6, Rochester, MN 55905, USA
2 Division of Anatomic Pathology, Mayo Clinic, Rochester, MN, USA
Received 1 March 2008; accepted after revision 25 May 2008.
* Corresponding author. Tel: +1 507 284 3297; fax: +1 507 284 3968. E-mail address: menon.shaji{at}mayo.edu
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Abstract
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We present two paediatric cases of a very rare, pathologically
benign, and primary cardiac tumour composed of mature cardiac
myocytes with disorganized cytoarchitecture called hamartoma
of mature cardiac myocyte. The patients are usually asymptomatic,
may have non-specific electrocardiogram findings, and rarely
have associated sudden death. The clinical presentation and
pathological and imaging findings of this rare tumour are discussed.
Cardiac magnetic resonance imaging may help differentiate this
tumour from other common differential diagnosis like cardiac
fibroma and hypertrophic cardiomyopathy.
Keywords: Cardiac hamartoma; Paediatric; Imaging
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Introduction
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Paediatric primary cardiac tumours are rare and are usually
considered benign, although they may locally infiltrate the
myocardium.
1 Hamartomas of mature cardiac myocyte are extremely
rare; only a handful of such tumours have been reported in the
literature.
1–7 Differentiating this rare tumour from other
tumours, such as fibroma, rhabdomyoma, and angiosarcoma, or
rarely from hypertrophic cardiomyopathy may pose considerable
difficulty.
4,5 We describe the clinical presentation, diagnostic
dilemmas, and imaging findings in two paediatric patients with
this rare tumour.
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Case 1
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A 16-year-old-female lost 25 pounds over 6 months. During evaluation
for possible associated eating disorder, she underwent a routine
electrocardiogram. The electrocardiogram revealed right axis
deviation, right ventricular hypertrophy, and inverted T waves
in II, III, AVF, and chest leads (
Figure 1A). She had no
history of cardiac symptoms, including chest pain, palpitation,
breathlessness on exertion, presyncope, or syncope. An echocardiogram
was performed at an outside institution and revealed a large
(8
x 7
x 3 cm) homogenous mass. She was referred to our institution
for further evaluation. Her echocardiogram revealed the mass,
extending along the posteroinferior free wall of the right ventricle
from right atrioventricular groove to the right ventricular
apex (
Figure 2) (see
Supplementary material online, Videos 1–3).
Medially, the mass also involved the lower aspect of interventricular
septum. The echodensity of the mass was similar to the remainder
of the myocardium; there was no clear line of demarcation between
the mass and rest of the myocardium. A small pericardial effusion
was also noted. Overall systolic function was normal, and there
was no notable valvular pathology. However, the tumour itself
was non-contractile with severely reduced tissue Doppler velocities.
A 24 h Holter study did not reveal any significant ectopy or
arrhythmia. To further delineate the mass, a cardiac magnetic
resonance imaging (CMR) scan was performed. Cardiac magnetic
resonance imaging clearly delineated the size and extent of
tumour (
Figure 3) (see
Supplementary material online, Videos 4 and 5).
There was markedly increased T2 signal intensity (
Figure 4),
rapid intense enhancement (first pass) after gadolinium contrast
(see
Supplementary material online, Video 6), and persistent
delayed enhancement (
Figure 5). All these features suggested
increased vascularity of the tumour.
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Figure 1 (A) Resting electrocardiogram of case 1 showing right axis deviation, right ventricular hypertrophy, and inverted T waves in II, III, AVF, and chest leads. (B) Resting electrocardiogram of case 2 showing left axis deviation and widespread ST-T wave changes in limb and lateral chest leads.
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Figure 2 (A) Apical-long-axis view, angled posteriorly showing the extent of tumour. (B) Subcostal coronal view showing the tumour and small pericardial effusion. (C) Parasternal short axis view showing the septal involvement and lack of line of demarcation between normal myocardium and tumour. LA, left atrium; LV, left ventricle; RV, right ventricle.
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In view of the extensive cardiac involvement, with history of
weight loss, suggested high vascularity of the tumour, and the
associated small pericardial effusion, the possibility of a
malignant tumour, such as angiosarcoma, was considered. The
patient underwent a right ventricular endomyocardial biopsy.
Histopathological examination revealed areas of hypertrophied,
disorganized, mature myocytes, variably interspersed among fibroblasts
and collagen (
Figure 6). In addition, there was myocyte
vacuolization, dilated venules, and thick-walled arteries. All
these findings confirmed the histological diagnosis of a hamartoma
of mature cardiac myocytes. On 4 month follow-up, she continues
to remain asymptomatic without change in echocardiographic appearance
or the occurrence of arrhythmias. Behavioural therapy and counselling
for her eating disorder has resulted in weight gain.
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Figure 6 Histopathology from case 1 (A) and case 2 (B) showing hypertrophied, disorganized, mature myocytes, variably interspersed among fibroblasts and collagen. A also shows dilated venules and thick-walled arteries.
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Case 2
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A 10-year-old Italian male was referred to our institution for
resection of a possible left ventricular fibroma. This tumour
was diagnosed on screening echocardiography following a routine
pre-sports electrocardiogram that showed left axis deviation
and widespread ST-T wave changes in limb and lateral chest leads
(
Figure 1B). He had no history of cardiovascular complaints,
including palpitations, arrhythmias, chest pain, presyncope,
or syncope. He was an avid soccer player, in excellent physical
condition. It was recommended that he undergo surgical resection
of the tumour in order to continue to participation in competitive
soccer, as the initial diagnosis was presumed fibroma, which
may be associated with ventricular arrhythmias and risk for
sudden death. An echocardiogram at our institution revealed
a mass along the anterosuperior aspect of the left ventricular
free wall, measuring 3
x 2 mm (
Figure 7) (see
Supplementary material online, Videos 7 and 8).
Similar to the previous case, the tumour appeared isointense
with no clear line of demarcation between the tumour and rest
of the myocardium. The echocardiographic features were consistent
with a left ventricular free wall fibroma. A 24 h Holter study
did not show any significant arrhythmia or ectopy. Cardiac magnetic
resonance imaging showed an elliptical tumour, along the anterosuperior,
free wall of the left ventricle (
Figure 8) (see
Supplementary material online, Videos 9 and 10).
On gadolinium contrast, imaging the tumour did not show any
significant early enhancement. The tumour was mildly hyperintense
on T2-weighted image (
Figure 9). However, there was diffuse
delayed enhancement.
At surgery, the mass appeared indistinguishable from rest of
the normal ventricular myocardium. Externally, the left ventricle
free wall mass appeared tumour-like. A fresh frozen section
performed during surgery revealed the diagnosis of a hamartoma
of mature cardiac myocytes with histological findings identical
to the case 1. Resection was abandoned at this stage. The patient
continues to be asymptomatic at 5 month follow-up.
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Discussion
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Hamartoma of mature cardiac myocytes was first described in
1988;
2 since then very few cases have been described. Hamartomas
are defined as tumours consisting of disorganized collections
of tissue components native to the organ in which they occur.
1–8 Although hamartomas of mature cardiac myocytes lack primitive
or aberrant cellular elements, their tissue architecture is
distinctly abnormal, and markedly enlarge myocyte forms can
be seen.
1 Still, hamartomas are benign and slow growing tumours
that usually do not involve surrounding structures. Their origin
is unknown, but congenital anomalous development of embryonic
cells seems most likely.
Hamartoma of mature cardiac myocyte should be distinguished from the more common rhabdomyoma and histiocytoid (oncocytic) cardiomyopathy, both of which have also been referred to as ‘cardiac hamartoma’.9 Rhabdomyomas, often seen in the setting of tuberous sclerosis, may be multiple and can often be detected during foetal or neonatal echocardiographic examination and generally regress over time. Rhabdomyomas are composed of mature cardiac tissue, but show massive vacuolation of the myocytes, giving the appearance of ‘spider cells’ on histology.9 Histocytoid (onocytic) cardiomyopathy is characterized by well-defined collections of myocytes showing pale granular material filling the sarcoplasm, presents in similar age group with presenting symptoms including tachyarrhythmia or sudden death, and tends to regress over time.9
Hypertrophic cardiomyopathy may share some histological findings with a hamartoma of mature cardiac muscle. However, these two disorders can be distinguished by lack of increased vascularity, more diffuse myocardial involvement, and characteristic septal localization of hypertrophic cardiomyopathy.5
Finally, a hamartoma of mature cardiac myocyte may be confused with cardiac fibroma, as described in our second case. Cardiac magnetic resonance imaging may provide valuable clues to help differentiate these entities. Hamartomas of mature cardiac muscle appears to be a vascular tumour with rapid early and persistent delayed enhancement following gadolinium contrast CMR. In the presence of increased vascularity, a hamartoma appears hyperintense on T2-weighted image and first-pass perfusion scan. In contrast, fibromas appear hypointense on first-pass perfusion image due to low tumour vascularity. On delayed myocardial enhancement images, fibromas demonstrate high signal intensity of the mass compared with the nulled normal myocardium.10 On cardiac computed tomogram, large fibromas may also contain areas of calcification.11
The clinical presentations in hamartoma of mature cardiac myocytes range from asymptomatic cases brought to attention secondary to non-specific electrocardiogram changes (as with our 2 cases), to presentation with ventricular and supraventricular tachycardia, and sudden death.3–7 Although, the tumour may be large and alters the ventricular shape, resection of the mass is difficult due to the lack of clear demarcation from the normal myocardium.
These two cases highlight the asymptomatic clinical presentation and imaging findings associated with an extremely rare, pathologically benign, and primary cardiac tumour ‘hamartomas of mature cardiac muscle’ presenting in paediatric age group. Wider clinical recognition of this rare entity may help to further differentiate this tumour from other relatively common causes of cardiac masses by non-invasive means.
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Supplementary data
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Supplementary data is available at European Journal of Echocardiography online.
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References
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- Martinez Quesada M, Trujillo Berraguero F, Almendro Delia M, Hidalgo Urbano R, Cruz Fernandex J. Cardiac hamartoma. Case report and literature review. Rev Esp Cardiol (2005) 58:450–542.[CrossRef][Web of Science][Medline]
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- Yan AT, Coffey DM, Li Y, Chan WS, Shayne AJ, Luu TM, et al. Images in cardiovascular medicine. Myocardial fibroma in gorlin syndrome by cardiac magnetic resonance imaging. Circulation (2006) 114:e376–e379.[Free Full Text]
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Abstract
Introduction
