Malignant fibrous histiocytoma complicating mitral valve replacement.

A 67 year old woman developed a fatal febrile illness 8 years after mitral valve replacement for rheumatic valvular heart disease. The final disease persisted for 1 year and was characterized clinically by weakness, weight loss, congestive heart failure and multiple embolic events to the central nervous system and abdominal organs. The source of the emboli was a tumor, malignant fibrous histiocytoma of the left atrium, originating from the anulus fibrosus around the covered base of the prosthetic valve. This unique case suggests the possibility that chronic exposure to materials, such as Dacron, covering prosthetic valves may induce local malignant tumors.