DEVELOPMENT OF ESSENTIAL THROMBOCYTHEMIA IN A PATIENT TREATED WITH INTERFERON-ALPHA AND PENTOSTATIN FOR HAIRY-CELL LEUKEMIA

A patient is reported who developed essential thrombocythemia after su ccessful treatment for hairy cell leukemia. He was initially treated w ith interferon alfa and subsequently relapsed within one year of treat ment. His diagnosis was reconfirmed and then treated with Pentostatin. Six years after treatment he had a progressive increase in the platel et count and was diagnosed as essential thrombocythemia. Second cancer s including various types of hematological malignancy have been report ed in patients with hairy cell leukemia treated with chemotherapy or i nterferon alfa. These malignancies may represent either a new clonal d isorder or a complication of drug treatment. This is the first report of a chronic myeloproliferative disorder following successful treatmen t of hairy cell leukemia.