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Primary cardiac lymphoma mimicking left atrial myxoma in an immunocompetent patient.

A 52-year-old obese Hispanic woman presented in March 2005 with a 1-week history of dizziness, leg swelling, orthopnea, exertional dyspnea, and nonradiating pain in the upper back. In the prior 2 months she also had paroxysmal cough and a 7-kg weight loss, but no fever, chills, or night sweats. She had type 2 diabetes, hypertension, and was status postangioplasty for renal artery aneurysm. She had bilateral jugular venous pulsation and basilar crackles, irregularly irregular rate and rhythm, 2 of 6 intensity systolic ejection murmur at the left sternal border, and trace edema of lower extremities. Notable laboratory values included hemoglobin of 9.3/dL, creatinine of 1.3 mg/dL, and erythrocyte sedimentation rate of 117 mm/h. Normal results included those for cardiac enzymes and HIV serology. Outside transthoracic echocardiography, confirmed after referral for resection, showed a left atrial mass of 7 3 cm that prolapsed intermittently through the mitral valve causing mitral regurgitation (Fig 1). Left ventricular systolic function was adequate. Chest x-ray showed cardiomegaly and mild pulmonary edema. ECG showed atrial fibrillation and lateral lead ST depression. Cardiac catheterization showed coronary artery stenoses up to 90% (of left anterior descending artery) and tumor blood supply from an atrial branch of the circumflex artery. Preoperative diagnosis was left atrial myxoma. Intraoperatively, the tumor was found friable, widely attached to the atrial septum and to the roof of the left atrium laterally to the superior vena cava juncture. A smaller tumor was between trabeculae and in the right lower pulmonary vein. Both were resected, preceded by two-vessel coronary artery bypass graft. The resected mass consisted of several fragments of soft tanbrown tissue (the largest one was 7 6 3.5 cm), together measuring up to 8 cm (Fig 2). On microscopy, fringes of tumor infiltrated adjacent cardiac muscle and other portions were necrotic. Tumor cells were intermediate to large transformed (noncleaved) lymphocytes, many exhibiting a plasmacytoid morphology with round nuclei and eosinophilic cytoplasm; other cells had nuclei with folded or irregular borders (Fig 2). On paraffin immunoperoxidase stains, tumor cells were CD20 coexpressing CD5, BCL-6, BCL-2, and up to 90% MIB-1 (Ki67). They were negative for CD10, EBER, CD23, cyclin D1, HHV8, CD43, CD2, CD138, CD56, immunoglobulin G (IgG), IgA, IgM, and light chains. The final diagnosis was diffuse large B-cell lymphoma. The postoperative course was complicated by cardiac and renal failure requiring transient ventilatory support, and hemodialysis. Obtundation and divergent gaze on day 13 was explained by magnetic resonance imaging, showing multiple small embolic infarctions. CSF cell count was normal and cytology was negative for malignancy. The patient received anticoagulants, recovered neurologically, and spontaneously converted to sinus rhythm on postoperative day 39. Computed tomography imaging showed lymph nodes of up to 1.5 cm in the aortocaval, right iliac, and left inguinal area. Bilateral bone marrow biopsies and aspirate were negative, including cytogenetic and flow cytometry immunophenotyping studies. On day 30 after surgery, cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab chemotherapy was started. After five cycles, it was terminated because of symptoms of undue fatigue. Work-up revealed occlusion of the internal mammary bypass graft to the left anterior descending artery. Transthoracic echocardiography was negative. Computed tomography restaging showed remission of subdiaphragmal lymphadenopathy. Reimaging in March 2007 confirmed complete remission. The patient is currently well 26 months after resection, and 23 months after last chemotherapy. Primary tumors of the heart are rare and 75% are benign. About half of these are solitary myxomas, usually involving the left atrium. Disseminated cancers and lymphomas rarely involve the heart, and usually have no cardiac symptoms. In contrast, primary cardiac non-Hodgkin’s lymphomas (PCLs) involve heart and/or