M-component with reactivity against actin associated with thrombotic thrombocytopenic purpura.

A patient with a monoclonal B-cell disorder producing an M-component with antiactin activity is described. After more than 3 years of observations, the final diagnosis is not completely established, but a malignant lymphoproliferative process is evidently under evolution. On three occasions, she has presented with symptoms compatible with a thrombotic thrombocytopenic purpura-like syndrome, concomitant with an increase in paraprotein. A relationship between this autoantibody and the patient's symptoms is proposed. Steroids have so far had a beneficial effect on the symptoms.