[Acute mitral regurgitation caused by malignant lymphoma of the posterior mediastinum].

An 82-year-old man was admitted to our hospital in September 1996 due to dysphagia and cardiomegaly. Physical examination detected the fourth heart sound and a Levine III/VI systolic murmur in the cardiac apex. Surface lymph nodes were not palpable. LDH 662 IU/I was detected by laboratory examinations, and ultrasound cardiography showed grade 3 mitral regurgitation. Computed tomography revealed a huge mass in the posterior mediastinum, pressing the heart from the posterior direction. Thereafter, a left pleural effusion developed and aspiration was performed. Cytological examination of the fluid showed clusters of lymphoid cells with a positive immunophenotype for CD10, CD19 and HLA-DR. Chromosome analysis revealed complex abnormal karyotypes including t(8;14) (q24;32). A diagnosis of B cell lymphoma was made, and combination chemotherapy consisting of cyclophosphamide, THP-adriamycin, vincristine, and prednisolone was initiated. The patient's mass disappeared promptly, and his mitral reguration subsided. We reported this case because malignant lymphoma of the posterior mediastinum is rare, and because we are unaware of any previous reports of malignant lymphoma causing acute mitral regurgitation.