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A 60-year-old man with a history of aortic valve (AV) replacement with a cryopreserved allograft for aortic stenosis presented with signs and symptoms of acute left ventricular failure. Transthoracic echocardiography revealed severe AV regurgitation, and the patient subsequently underwent AV replacement with a mechanical prosthesis for the degenerative insufficiency of his prosthetic allograft. The explanted valve was noted to have vegetation-like lesions (Fig. 1). A histopathologic examination showed extensive involvement of the valvular tissue with a large-cell malignant neoplasm (Fig. 2A). The malignant cells stained strongly for CD20 (Fig. 2B) with an aberrant expression of CD43; they were negative for CD3, which suggested large B-cell lymphoma as the diagnosis. A nuclear Ki 67 positivity of 0.80 to 0.90 also raised the possibility of Burkitt's lymphoma, but the diagnostic criteria were not met. The patient's blood counts were normal, and a bone-marrow biopsy showed no evidence of lymphoma. Positron emission tomography of the head, chest, abdomen, and pelvis also yielded negative results. The patient tested negative on screening for human immunodeficiency virus, but he was not tested for Epstein-Barr virus. Two years later, he died of Staphylococcus aureus tricuspid valve endocarditis and severe pneumonia.
Primary malignant cardiac tumors are rare (0.002%–0.3% in autopsy series),1,2 and cardiac lymphomas comprise 1.5% to 5% of all primary malignant cardiac tumors.2 To the best of our knowledge, this is the 1st report of a patient with diffuse large B-cell lymphoma in a prosthetic AV allograft. Transfer of neoplastic tissue from donor to recipient in our patient is highly unlikely, because the valve had been in place for 10 years before his presentation.
Observation in animals has indicated that surgical polymeric materials are carcinogenic in 7% to 50% of exposures.3 In a MEDLINE® search of English-language articles for prior reports of Dacron-associated cardiac malignancies in human beings, we found only 3 cases, all of which involved prosthetic mitral valve malignancy.2,4,5 We wonder if the Dacron in our patient's graft caused the neoplastic transformation. Given the large number of grafting procedures performed annually, such risk in human beings appears to be negligible.
Address for reprints: Nishith K. Singh, MD, Department of Internal Medicine, Southern Illinois University School of Medicine, 701 N. First St., Springfield, IL 62794–9636