Chronic myelogenous leukemia following repeated radiation therapy for histiocytosis X.

Low dose radiotherapy has been used to treat a variety of benign disorders including Histiocytosis X. Ionizing radiation may be leukemogenic with leukemia developing between 3.5 to 11 years after exposure. Twenty to 30% of these leukemias are chronic myelogenous leukemia (CML). In this report the rare development of PH1 + CML 11 years after radiation therapy for Histiocytosis X is recorded.