Rituximab treatment for thrombotic thrombocytopenic purpura associated with human immunodeficiency virus failing extensive treatment with plasma exchange: a report of two cases.

In an urban area with a 3% prevalence of HIV infection, two women presented in a 1-year period with AIDS and thrombotic thrombocytopenic purpura (TTP). TTP was diagnosed in each patient based on the presence of thrombocytopenia, schistocytes, and markedly elevated lactate dehydrogenase (LDH) activity. Initial treatment with plasma exchange resulted in resolution of these abnormalities. However, the discontinuation of plasma exchange resulted in the prompt recurrence of laboratory abnormalities diagnostic for TTP. Treatment failure was established after observing 6 and 4 such responses requiring 41 and 40 episodes of plasma exchange for each patient, respectively. Patients were subsequently treated with 2-4 doses of weekly rituximab resulting in durable remission. These patients are now 21 and 9 months beyond rituximab treatment. Rituximab appears to be safe and effective in this setting.