Multiple myeloma after treatment of essential thrombocythemia

An 83-year-old black woman with previously diagnosed essential thrombocythemia was treated with thiotepa to control the excessive number of platelets. Approximately 10 years later, multiple myeloma developed. This appears to be the first case of multiple myeloma occurring after alkylating agent therapy for essential thrombocythemia. Although the mechanism of the development of multiple myeloma has yet to be defined, continuing progress in cell biology may prove a strong association between multiple myeloma and other hematologic malignancies.