Primary Cardiac Malignancy Masquerading as Mitral Valve Stenosis
A60-year-old white woman presented with a history of exertional shortness of breath rapidly progressing to orthopnea and episodes of paroxysmal nocturnal dyspnea over a period of 4 weeks. Her past medical history included hypertension; sick sinus syndrome, for which she had received a pacemaker; and a left carotid endarterectomy. Physical examination revealed normal vital signs, jugular venous distension of 5 cm, bibasilar rales, and a II/VI middiastolic murmur heard at the apex of the heart without an opening snap.
A transthoracic echocardiogram revealed a markedly thickened anterior leaflet of the mitral valve with limited diastolic excursion (Figure 1A⇓). A possible mass hugging the atrial side of the anterior leaflet could not be excluded. The posterior leaflet had preserved motion. Doppler echocardiography across the mitral valve obtained a mean gradient of 20 mm Hg, with a peak gradient of 47 mm Hg and a calculated valve area of 1.57 cm2 by the pressure half-time method (Figure 1B⇓). The transesophageal echocardiogram delineated a mass involving the anterior leaflet of the mitral valve and extending to the interatrial septum, with consequent obstruction of the valve (Figure 1C⇓ and 1D⇓). The left atrium was otherwise normal.
The patient was treated symptomatically for pulmonary edema, and after a coronary angiogram, which revealed single-vessel disease, she underwent exploratory cardiac surgery. During surgery, a large, multilobar, myxomatous mass 4 cm in diameter was seen on the anterior leaflet of the mitral valve. The mass had no distinct stalk, and it extended into the posterior commissure and the interatrial septum (Figure 2A⇓). In addition, islands of fibrinous, gelatinous material that were histologically similar to the mass were also visualized in the left atrium. The patient underwent excision of the mass, mitral valve replacement with a 27-mm St Jude’s valve, and a right coronary artery bypass graft.
Histologically, the mass consisted of a malignant proliferation of spindle cells arranged in storiform pattern with focal myxoid changes. The cells displayed marked nuclear pleomorphism with occasional bizarre cells and frequent mitotic figures, including abnormal forms (Figure 2B⇓ and 2C⇓). Immunohistochemistry revealed negative staining for desmin and smooth muscle actin. Tumor cells were strongly immunoreactive for CD-68 (Figure 2D⇓) and focally with desmin. Electron microscopy demonstrated features consistent with a fibrohistocytic differentiation (Figure 2E⇓). The diagnosis was primary endocardiac malignant fibrous histiocytoma. The patient underwent adjuvant chemotherapy and is alive and well 1 year after surgery.
Reprint requests to R. Sheahan, MD, Division of Cardiology, University of Texas Medical Branch at Galveston, 301 University Blvd, Galveston, TX 77555.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
Circulation encourages readers to submit cardiovascular images to Dr Hugh A. McAllister, Jr, St Luke’s Episcopal Hospital and Texas Heart Institute, 6720 Bertner Ave, MC1-267, Houston, TX 77030.
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