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Year : 2018  |  Volume : 4  |  Issue : 1  |  Page : 55-58

Hamartoma of mature cardiac myocytes: Report of a rare case with review of literature

1 Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
2 Department of Cardiovascular Radiology and Endovascular Intervention, All India Institute of Medical Sciences, New Delhi, India
3 Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences, New Delhi, India

Date of Web Publication4-May-2018

Correspondence Address:
Dr. Sudheer Arava
Department of Pathology, All India Institute of Medical Sciences, New Delhi - 110 029
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jpcs.jpcs_15_18

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Hamartoma of mature cardiac myocyte is a benign tumor of the heart. They are characterized by haphazardly arranged hypertrophic cardiac myocytes with variable amounts of intervening fibrosis, mature adipose tissue along with irregularly distributed variable-sized vascular channels. The case presented here had a hyperechoic mass in the left ventricle arising from the midinferior and posterior interventricular septum, infiltrating into the adjacent myocardium. The MRI , histopathology findings and the clinical outcome is presented.

Keywords: Hamartoma of mature cardiac myocytes, sudden cardiac death, tumor-like lesion

How to cite this article:
Kumari K, Arava S, Kumar S, Bansal A, Bisoi AK, Ray R. Hamartoma of mature cardiac myocytes: Report of a rare case with review of literature. J Pract Cardiovasc Sci 2018;4:55-8

How to cite this URL:
Kumari K, Arava S, Kumar S, Bansal A, Bisoi AK, Ray R. Hamartoma of mature cardiac myocytes: Report of a rare case with review of literature. J Pract Cardiovasc Sci [serial online] 2018 [cited 2023 May 31];4:55-8. Available from: https://www.j-pcs.org/text.asp?2018/4/1/55/231929

  Introduction Top

Hamartoma of mature cardiac myocyte (HMCM) is a recently recognized entity classified under benign tumor and tumor-like lesions of the heart (WHO 2015 classification). It was first described by Tanimura et al. in 1988.[1] Till now, approximately 25 cases have been reported in the literature. These lesions are usually solitary and commonly arise from the ventricular-free wall followed by interventricular septum and rarely in the atrial musculature. Occasional cases arising from the atrioventricular valves have also been reported.[2],[3] Exact incidence and precise etiology of these lesions are not known due to its rarity. As these lesions are slow growing, affected individuals present with variable and nonspecific clinical features. Tiny lesions if present are incidental and clinically asymptomatic,[3] but on rare occasions, they may present with tumor-like nodule and may cause sudden cardiac death. Radiologically, HMCM presents as a localized, slow-growing, and intramural mass-like lesion with variable radiological differentials such as rhabdomyoma, hypertrophic cardiomyopathy (HCM), fibroma, and hemangioma.[4],[5] Definitive diagnosis of these lesions is made only on histological examination of the excised specimen. Microscopically, they are characterized by haphazardly arranged hypertrophic cardiac myocytes with variable amounts of intervening fibrosis, mature adipose tissue along with irregularly distributed variable-sized vascular channels.[6] The present case has been highlighted due to its rarity, large infiltrative tumor-like presentation on radiology, and variable histopathological features. Knowledge regarding this entity and its close histopathological mimics is important for the proper identification and definitive treatment.

  Case Report Top

A 43-year-old male presented to the cardiology outpatient with complaints of intermittent chest pain, orthopnea, and palpitation for 3 months' duration which aggravated on moderate exertional activities. Echocardiography (ECHO) revealed hyperechoic mass in the left ventricle arising from the midinferior and posterior interventricular septum, infiltrating into the adjacent myocardium. Cardiac magnetic resonance imaging (MRI) and computed tomography revealed an irregular sessile heterogeneous mass-like lesion measuring 8 cm × 6 cm present in the inferoseptal wall of the left ventricular cavity with involvement of the posteromedial papillary muscle. The lesion was isointense on T1-weighted images and mildly hyperintense on T2-weighted images [Figure 1]a-c].Late gadolinium enhancement (LGE) showed relatively homogeneous enhancement [Figure 1]d. The tumor was replacing the entire thickness of the ventricular wall without any evidence of calcification, fatty infiltration, or necrosis. Rest of the cardiac chambers along with the left ventricular function and coronaries were normal. Based on imaging findings, the possibilities considered were rhabdomyoma and hemangioma, and the patient was admitted for surgical excision of the mass. With proper preanesthetic evaluation, the patient underwent median sternotomy and vertical pericardiotomy. Aortic bicaval cannulation and debulking of the tumor were done. Papillary muscle was spared to retain the proper functioning of the mitral valve. Ventriculotomy site was closed with soft felt on both sides. The excised specimen was fixed in 10%-buffered formalin and was sent for histopathological confirmation. Grossly, the excised specimen measured 5 cm × 4 cm × 3 cm. Cut section was firm, homogeneous, and greyish brown in color. Degenerative areas such as cystic change, calcification, hemorrhage, or necrosis were not identified. Microscopic examination from the different areas of the lesion revealed an unencapsulated, poorly circumscribed lesion [Figure 2] primarily composed of haphazardly arranged hypertrophied cardiac myocytes [Figure 3]e with variable admixture of blood vessels, mature adipocytes, and interstitial fibrosis. Predominant component of the lesion was haphazardly arranged; hypertrophied cardiac myocytes displaying nucleomegaly with variable nuclear size. Second predominant component was variable-sized capillaries, thick and thin walled blood vessels displaying irregular medial hypertrophy [Figure 2] and [Figure 3]a. At places, in the vicinity of thick-walled dilated vessels, network of numerous capillary-sized vessels was also identified. Third component was composed of lobules of mature adipocytes occupying approximately 15%–20% of the total lesional area [Figure 2]. Masson trichrome stain revealed prominent interstitial fibrosis [Figure 3]b and [Figure 3]c. Significant inflammation, dystrophic calcification, hypertrophied nerve bundles, mitosis, and necrosis were not identified. An immunohistochemical panel done revealed CD31 positivity in the vascular endothelium [Figure 3]d, smooth muscle actin positivity the vascular media [Figure 3]f, and S100 immunostain positivity in the mature adipocyte nucleus. However, immunohistochemistry for human melanoma black (HMB)-45, CD117, and Melan-A were negative. The proliferative index of the tumor (MIB-1 labeling index) was <1%. Based on the above histomorphological and immunohistochemical findings, a final diagnosis of HMCMs was made. A thorough clinicoradiological examination did not reveal any evidence of similar lesion elsewhere in the body. The postoperative period was clinically uneventful; however, postoperative ECHO and radiology showed a small residual lesion with minimal mitral regurgitation with normal left ventricular functions.
Figure 1: Photomicrograph showing magnetic resonance imaging images (4-chamber view) of heart showing relatively well-defined mass lesion in the left ventricle midcavity region with no clear demarcation with the ventricular wall. T1-weighted image shows an isointense mass (a). T2-weighted image is showing a mildly hyper intense mass (b). Contrast-enhanced computed tomography image of heart (4-chamber view) depicts a well-defined heterogeneous mass in the left ventricular cavity attached to inferoseptal wall. Calcification or fatty infiltration was absent (c). Late gadolinium enhancement images revealed homogeneous enhancement (d). Left atrium (*); Right atrium (#); Right ventricle (+); Left ventricle (); DTA: Descending thoracic aorta

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Figure 2: Photomicrograph depicting an unencapsulated poorly circumscribed lesion (a, H and E, ×200). It composed of haphazardly arranged cardiomyocytes admixed with malformed thick-walled venules, thin-walled capillaries, and mature adipose tissue (b and c, ×200). Vessels showing irregular medial hypertrophy (d and e, ×200). Intervening network of capillary-sized vessels confined to the vicinity of thick-walled vessels (f and g, ×200). Myocytes showing hypertrophic changes (h, ×200). Interstitial thick and large anastomosing muscle bundles (i, ×200)

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Figure 3: Photomicrograph shows absence of internal elastic lamina in the vessel wall (a, Verhoeff–van Gieson, ×200). Masson trichrome stain highlights the prominent fibrosis in the interstitium and the venular wall (b and c, ×200). CD31 immunostain is decorating the endothelial cells (d, ×200). Myocytes are immunopositive for desmin (e, ×200). Smooth muscle in the venular wall is positive for smooth muscle actin (f, ×200)

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  Discussion Top

HMCM is an extremely rare tumor-like lesion of the heart with approximately 25 reported cases in the literature. It is mainly sporadic without any known genetic association. Majority of these lesions were discovered incidentally in autopsy with unrelated cause of death. Thorough literature review showed that the mean age of presentation is 35 years; however, few cases have also been reported in infants, preadolescent, and adolescent with age ranging from 6 months to 74 years.[7],[8],[9] Most of the patients were clinically asymptomatic, and the lesion was identified as an incidental finding.[3] In few cases, clinical presentation was nonspecific which included chest pain, dyspnea, dizziness, syncope, and rarely sudden cardiac death. The clinical symptoms largely depend on the size, location, and infiltration of the lesion into the adjacent myocardium. The electrocardiographic findings will be nonspecific in all the cases. The average size range of the HMCM reported varies from 1 to 91 mm.[6] HMCM are usually solitary; however, a single case in Fealy et al.'sreport showed multiple hamartomatous ventricular and atrial lesions in a 9-year-old boy with a history of sudden cardiac death.[6] Radiologically, HMCM mimics various tumor and tumor-like lesions of the heart which include rhabdomyoma, myxoma, hemangioma, fibroma, and arteriovenous malformations. Cardiac MRI usually shows mildly hypointense to hyperintense signal on T2-weighted images, intermediate signal on T1-weighted images, and avid enhancement reported on early and delayed postcontrast images.[4],[5] Histopathological examination of the excised specimen is the only way for the definitive diagnosis of this lesion. Histological differentials that should be considered in the evaluation are vascular malformation, hemangioma, hypertrophied cardiomyopathy, and fibroma. The absence of nerve bundles and absence of internal elastic lamina in thick-walled vascular channels on special stain rule out vascular malformations. Hemangiomas commonly show predominant lobular proliferation of capillary-sized vessels or cavernous-sized dilated and congested blood vessels with variable admixture of inflammatory cells. Haphazardly arranged hypertrophic cardiac myocytes and admixture of mature adipocytes are usually not seen. Cardiac fibromas are firm in consistency, and on microscopy, they show varying degree of fibrosis with proliferation of fibroblasts and myofibroblasts in a collagenous background.[10] Haphazardly arranged hypertrophic cardiac myocytes, adipose tissue, and blood vessels are not seen, and radiologically, these lesions show characteristic LGE. HCM is an important differential that should be considered, especially when the lesion is septal in location. Important histological findings such as crisscross arrangement of cardiac myocytes with plexiform fibrosis which are characteristic of HCM will not be present in these lesions. In addition, variable-sized big thick-walled vascular channels and lobules of mature adipose tissue will not be seen in HCM.[8] As the lesion contained adipose tissue and vascular component, to exclude the remote possibility of angiomyolipoma, we carried out HMB-45, CD117, and Melan A immunohistochemical stains, but all were negative.

Surgical indications in clinically symptomatic cases are mainly due to the lesion causing intracavitary obstruction, rhythmic disturbances, and for altered myocardial contractility. Complete surgical resection is the mainstay of treatment with no or minimal recurrence rates, and it carries a very good prognosis. However, at times, complete resection of the lesion is rather difficult due to the infiltrative margins and lack of clear circumscription. Because of this, all patients should be kept on long follow-up to see any evidence of recurrence. The present case after 2 years of follow-up revealed a residual lesion without any significant progression and clinical symptoms.

  Conclusion Top

HMCM is a rare nonneoplastic tumor and tumor-like lesion of the heart that can mimic various cardiac lesions and tumors. Clinical symptoms and radiological features are nondiagnostic as they render various differentials. Histopathological examination is the only way for a definitive diagnosis. Complete surgical excision with clear margins is the treatment of choice with an excellent prognosis and minimal recurrence rates.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Tanimura A, Kato M, Morimatsu M. Cardiac hamartoma. A case report. Acta Pathol Jpn 1988;38:1481-4.  Back to cited text no. 1
Raffa GM, Malvindi PG, Settepani F, Melotti F, Monti L, Spaggiari P, et al. Hamartoma of mature cardiac myocytes in adults and young: Case report and literature review. Int J Cardiol 2013;163:e28-30.  Back to cited text no. 2
Fazio G, Grassedonio E, Cracolici E, Novo G, Sutera L, Pipitone S, et al. Cardiovascular magnetic resonance characterization of a hamartoma in an asymptomatic child. Int J Cardiol 2009;132:e102-4.  Back to cited text no. 3
Raikhlina A, Torresb FS, Nguyenc ET. Cardiac hamartoma: Magnetic resonance and computed tomographic imaging. Eur J Radiol Extra 2011;78:85-8.  Back to cited text no. 4
Abuzaid AS, Gakhal M, Montgomery E, LaPoint R, Horn R, Banbury MK. Cardiac hamartoma: A diagnostic challenge. Cardiovasc Imaging Case Rep 2017;1:2.  Back to cited text no. 5
Fealey ME, Edwards WD, Miller DV, Menon SC, Dearani JA. Hamartomas of mature cardiac myocytes: Report of 7 new cases and review of literature. Hum Pathol 2008;39:1064-71.  Back to cited text no. 6
Dell'Amore A, Lanzanova G, Silenzi A, Lamarra M. Hamartoma of mature cardiac myocytes: Case report and review of the literature. Heart Lung Circ 2011;20:336-40.  Back to cited text no. 7
Gilman G, Wright RS, Glockner JF, Starrett RS, Hansen WH, Sinak LJ, et al. Ventricular septal hamartoma mimicking hypertrophic cardiomyopathy in a 41-year-old woman presenting with paroxysmal supraventricular tachycardia. J Am Soc Echocardiogr 2005;18:272-4.  Back to cited text no. 8
Shetty V, Kumar PH, Raj V, Ramaiah S, Madhuprakash SC. Right atrial hamartoma: A rare entity. Ind J Thorac Cardiovasc Surg 2017;33:241-3.  Back to cited text no. 9
Mustafa EM, Reibiero Ferreira VR, Sabino SB, Braile-Sternieri MC, Sestito RS, Leal JC, et al. Rare case of hamartoma mimicking fibroma and correlations with literature. J Clin Exp Cardiol 2017;8:1.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3]

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