Ann Thorac Surg 1998;66:931-933
© 1998 The Society of Thoracic Surgeons
Case Reports
Interleukin-6 and "complex" cardiac myxoma
Yoshihiko Mochizuki, MDa,
Yoshitaka Okamura, MDa,
Hiroshi Iida, MDa,
Hideaki Mori, MDa,
Kouichiro Shimada, MDa
a Department of Thoracic and Cardiovascular Surgery, Dokkyo University School of Medicine, Tochigi, Japan
Accepted for publication March 16, 1998.
Address reprint requests to Dr Mochizuki, Department of Thoracic and Cardiovascular Surgery, Dokkyo University School of Medicine, 880 Kitakobayashi Mibucho Shimotsugagun, Tochigi, 321-02, Japan
e-mail: (mochi{at}dokkyomed.ac.jp)
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Abstract
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A rare case of "complex" cardiac myxoma is reported. Complex cardiac myxoma manifests with more constitutional signs than the sporadic type. These constitutional signs are known to be associated with the overproduction of interleukin-6 by cardiac myxomas. In our study, immunohistochemical staining of the myxoma for interleukin-6 was strongly positive. The serum interleukin-6 level decreased after surgical removal of the tumor and has remained undetectable for the past 2 years.
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Introduction
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Although cardiac myxomas and in particular the "complex" type often manifest with constitutional signs, the pathogenesis of these signs remains obscure. Recently, serum interleukin-6 (IL-6) levels have been associated with the appearance of constitutional signs in cardiac myxoma patients [1, 2]. Takahara and associates [3] used immunohistochemical staining of sporadic cardiac myxoma to demonstrate that IL-6 is localized within the tumor cells. We describe a rare case of a 14-year-old boy with complex cardiac myxoma. In addition, the relationship between this type of myxoma and IL-6 was examined by following up the changes in serum IL-6 levels and immunohistochemical staining of the excised tumor for IL-6.
A 14-year-old boy presented with a 2-week history of fever and exertional dyspnea. His temperature was 38°C, and a grade 3/6 systolic murmur was most strongly heard at the apex. Skin examination revealed numerous lentigious lesions covering the body, particularly about the face and lips. The erythrocyte sedimentation rate was 70 mm/h, and the white blood cell count was 5,100/µL. The serum C-reactive protein level was 6.7 mg/dL, and the serum IL-6 level was 11.0 pg/mL (IL-6 is usually not detected in the serum of healthy people) (Fig 1). The serum 
-globulin level was normal. No positive familial history for myxoma or lentigo was noted. Two left atrial tumors were revealed by two-dimensional echocardiography, and one of them was seen to move into the left ventricle during diastole. Color-flow Doppler echocardiography showed mitral regurgitation, and cardiac catheterization revealed mild mitral regurgitation.
The patient underwent an open heart operation in which two left atrial myxomas were removed in addition to underlying atrial septal endocardium. Both myxomas were excised with a portion of septum around the pedicle. An atrial septal defect, caused by the tumor excision maneuver, was closed with Dacron fabric. Half of the tumor was rapidly frozen at -196°C, and sections were immunohistochemically stained (with the avidin-biotin peroxidase complex method). The primary antibody was the mouse-monoclonal antibody, anti-human IL-6 clone 8 (Collaborative Biomedical Products Co, Bedford, MA). The remainder of the tumor was fixed in formalin and stained with hematoxylin and eosin. Microscopic examination revealed that IL-6 was localized to the interstitial region in the tumor, in particular around the blood vessels (Fig 2). Tumor histology as determined by hematoxylin and eosin staining was typical of myxoma.
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Fig 2. Photomicrograph of immunohistochemically stained specimen of myxoma. Positive interleukin-6 staining is evident as brown tissue and cells surrounding blood vessel. (Primary antibody: mouse monoclonal anti-human interleukin-6; x66 before 39% reduction.)
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The patient’s postoperative recovery was uneventful. The serum IL-6 level decreased rapidly after the operation and has remained undetectable for the last 2 years (see Fig 1). The constitutional signs permanently disappeared. No recurrence of the myxoma has occurred to date.
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Comment
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Recent studies have indicated that IL-6 production by cardiac myxoma cells may explain the constitutional symptoms [2, 5]. Interleukin-6 causes differentiation of B-cells into antibody forming cells, raises the serum C-reactive protein level, and causes the constitutional signs. In our patient, the serum IL-6 level was high preoperatively and decreased soon after the operation. In addition, immunohistochemical examination localized IL-6 to the myxoma cells. These results appear to confirm that cardiac myxoma cells produce IL-6, which in turn induces constitutional signs.
McCarthy and associates [4] have reported that complex cardiac myxomas often recur (sporadic type recurrence rate, 1% to 3%; complex type recurrence rate, 22%) and have emphasized the necessity for close postoperative follow-up of these patients. In our patient, who was diagnosed as having complex cardiac myxoma, echocardiography and the measurement of the serum IL-6 level was used to monitor recurrence. Although echocardiography is currently the best method for discovering cardiac myxomas, no small myxomas, which would be indicative of recurrence, were found. Furthermore, although the serum IL-6 level appears to be a good parameter for monitoring and identification of recurrence, serum IL-6 levels are often not elevated in patients with cardiac myxoma [2]. Although the serum IL-6 level remains undetectable in our patient and echocardiography shows an absence of tumor tissue in the heart, recurrence is an ever-present possibility. Therefore, to facilitate early detection of recurrence, the serum IL-6 level will be continuously measured in this patient, and echocardiography also will be performed.
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References
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- Hirano T., Taga T., Yasukawa K., et al. Human B-cell differentiation factor defined by an anti-peptide antibody and its possible role in autoantibody production. Proc Natl Acad Sci USA 1987;84:228-231.[Abstract/Free Full Text]
- Jourdan M., Bataille R., Seguin J., Zhang X.G., Chaptal P.A., Klein B. Constitutive production of interleukin-6 and immunologic features in cardiac myxomas. Arthritis Rheum 1990;33:398-402.[Medline]
- Takahara H., Mori A., Tabata R., Watarida S., Onoe M., Okabe H. Left atrial myxoma with production of interleukin-6. Nippon Kyobu Geka Gakkai Zasshi 1992;40:326-329.[Medline]
- McCarthy P.M., Piehler J.M., Schaff H.V., et al. The significance of multiple, recurrent, and "complex" cardiac myxomas. J Thorac Cardiovasc Surg 1986;91:389-396.[Abstract]
- Seguin J.R., Beigbeder J.Y., Hvass U., et al. Interleukin-6 production by cardiac myxomas may explain constitutional symptoms. J Thorac Cardiovasc Surg 1992;103:599-600.[Medline]
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Abstract
Introduction
