Successful treatment of essential thrombocythemia evolving into agnogenic myeloid metaplasia with interferon-α

Purpose: Essential thrombocythemia and agnogenic myeloid metaplasia as one form of idiopathic myelofibrosis are myeloproliferative disorders and are quite rare in children. A patient with essential thrombocythemia that transformed to "adult-type" agnogenic myeloid metaplasia is described. Patients and Methods: A routine examination of an 8-year-old girl with bronchial asthma showed thrombocytosis. Essential thrombocythemia was diagnosed 2 years later. During a 3-year follow-up without treatment, transition of the essential thrombocythemia to agnogenic myeloid metaplasia was noticed. The patient had an excellent response to interferon (IFN)-alpha therapy. Conclusion: This case is unique because of the availability of premorbid hematologic data and the natural progression of essential thrombocythemia to agnogenic myeloid metaplasia. Whether IFN-alpha therapy can prevent the progression of idiopathic myelofibrosis to leukemia has not yet been determined.