Diffuse large B-cell lymphoma in an aortic valve allograft.

Abstract

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. Fig. 1 Gross examination of the excised aortic valve showed multiple vegetation-like growths. Fig. 2 A) Light microscopy with routine staining of valve vegetations shows a mildly pleomorphic large-cell neoplasm with a vesicular chromatin pattern and a brisk mitotic rate (H & E, orig. ×40). B) The malignant cells stained strongly ...