Successful treatment of a patient with hairy cell leukemia and pentostatin-induced autoimmune thrombocytopenia with rituximab.
The treatment of choice for hairy cell leukemia (HCL) are the purine analogs pentostatin and cladribine. They induced complete remissions in up to 85% of patients. Purine analogs are known to induce autoimmune phenomena, but there are no reports of autoimmune thrombocytopenia after treatment with pentostatin. This case report describes the very rare association of pentostatin-treated hairy cell leukemia and autoimmune thrombocytopenia. Encouraged by first reports of promising activity of the anti-CD20 monoclonal antibody rituximab in patients with autoimmune disorders, we decided to treat our patient with rituximab in the conventional dose of 375 mg/m(2) i.v. weekly for 4 cycles. One week after the first administration, the peripheral blood count has recovered with a normal platelet count. 22 weeks after completion of therapy, the patient is still in complete hematologic remission without further medication. In conclusion, rituximab seems to be a new, promising drug in the treatment of refractory autoimmune thrombocytopenia even in patients with underlying lymphoproliferative disorders.