Asian Cardiovasc Thorac Ann 2008;16:e47-e48
© 2008 Asia Publishing EXchange Ltd
Mature Cardiac Myocyte Hamartoma in the Right Atrium
Namvar Movahedi, MD,
Mohammad Ali Boroumand, MD1,
Maryam Sotoudeh Anvari, MD1,
Parin Yazdanifard, MD2
Cardiothoracic Surgery Department
1 Clinical and Surgical Department of Pathology
2 Clinical Research Department, Tehran Heart Center, Medical Sciences University of Tehran, Tehran, Iran
For reprint information contact: Maryam Sotoudeh Anvari, MD Tel: 98 2188029256 Fax: 98 2188029256 email: maryamsotoudeh2006{at}yahoo.com, Tehran Heart Center, Medical Sciences University of Tehran, North Kargar Street, Tehran, Iran, 1411713138.
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ABSTRACT
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During coronary artery bypass grafting in a 58-year-old man, a mass was discovered incidentally in the right atrium, measuring 1.5 x 1 x 0.5 cm. It was composed of disorganized hypertrophic mature cardiac myocytes, and associated with focal fibrosis, mature adipocytes, and mild lymphocytic infiltration in peripheral areas, indicative of cardiac hamartoma. This type of hamartoma has been rarely reported as an isolated mass in the right atrium.
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INTRODUCTION
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Primary cardiac tumors are rare and usually benign. Hamartoma is a benign overgrowth of mature differentiated cells of the organ in which it is found. The mass results from anomalous development of embryonic cells.1 It grows noninvasively in line with the rate of the surrounding tissue, and ceases when the affected organ reaches maturity. In the heart, hamartomas with the characteristic histological appearance of mature cardiac myocytes are rare, especially as an isolated mass in the right atrium.2
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CASE REPORT
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A 58-year-old man presented with progressively worsening chest pain for 1 month. He had history of hyperlipidemia and smoking. There was no significant past medical history or family history of arrhythmia or other cardiac disease. An electrocardiogram showed normal sinus rhythm. Echocardiography revealed trivial mitral regurgitation, mild aortic valve thickening, mild tricuspid regurgitation, mild hypertrophy of the interventricular septal wall, and no evidence of a mass. Coronary angiography showed significant stenosis in the left anterior descending coronary artery (100%), right coronary artery (100%), circumflex artery (70%–90%), and obtuse marginal (50%–70%), and an ejection fraction of 45%. Coronary artery bypass grafting was undertaken. On right atrial cannulation, multiple clot-like fragments entered the cannula. The material was sent for histopathological examination. Coronary artery bypass grafting was performed, and the patient has remained asymptomatic for 2 months postoperatively.
Macroscopically, the specimen consisted of multiple fragments of dark brown clot-like tissue, measuring 1.5 x 1 x 0.5 cm. A small creamy-gray mass with irregular shape, measuring 1.1 x 0.4 x 0.4 cm was present. Microscopically, sections revealed a demarcated mass consisting of enlarged mature myocytes with disorganization, some of the cells were vacuolized with focal fibrosis, malformed blood vessels, and nests of mature adipocytes (like epicardium). Spider-like cells were not seen. Focal mature adipocytes were noted with mild lymphocytic infiltration in the peripheral area (Figure 1
). A fragment of fibrinous blood clot was seen adjacent to the mass. Periodic acid-Schiff staining with and without diastasis was negative (Figure 2).
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Figure 1. Microscopy of the right atrial mass; (A) At low magnification, the tumor was composed of disorganized hypertrophied myocytes (original magnification x4), (B) At higher magnification, enlarged myocytes with clear cytoplasm in disarray were visible (original magnification x40).
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Figure 2. Negative periodic acid-Schiff staining was helpful to rule out cardiac rhabdomyoma.;(A) Original magnification x10, (B) Original magnification x40.
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DISCUSSION
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In the heart, hamartomas of mature cardiac myocytes are rare.2 They consist of unencapsulated nodules of enlarged hypertrophied mature myocytes with a variable amount of collagen and fat.1,3 Isolated hamartomas in the right atrium have seldom been described perviously. Burke and colleagues1 reported hamartomas of mature cardiac myocytes in 3 patients, of whom only one had a mass in the right atrium. In 2002, Machida and colleagues4 reported a case of cardiac hamartoma in the right atrium of an 8-year-old dog.
The mass in the right atrium of our patient was found incidentally, and it confirms that the clinical presentation of cardiac hamartoma, similar to other localized cardiac masses, varies according to its location in the heart.
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REFERENCES
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- Martinez Quesada M, Trujillo Berraquero F, Almendro Delia M, Hidalgo Urbano R, Cruz Fernandez JM. Cardiac hamartoma. Case report and literature review. Rev Esp Cardiol 2005; 58:450–2.[Medline]
- Burke AP, Ribe JK, Bajaj AK, Edwards WD, Farb A, Virmani R. Hamartoma of mature cardiac myocytes. Hum Pathol 1998; 29:904–9.[Medline]
- Sturtz CL, Abt AB, Leuenberger UA, Damiano R. Hamartoma of mature cardiac myocytes: a case report. Mod Pathol 1998; 11:496–9.[Medline]
- Machida N, Katsuda S, Yamamura H, Kashida Y, Mitsumori K. Myocardial hamartoma of the right atrium in a dog. J Comp Path 2002; 127:297–300.[Medline]
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ABSTRACT
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