Secondary chronic myelogenous leukemia: A diverse pathogenesis?

A patient with myasthenia gravis and a thymoma did not respond to thymectomy. He was submitted to radiotherapy concurrent with steroid therapy followed by an alkylating based chemotherapy. Four years later, he developed an otherwise typical Philadelphia chromosome/BCR-ABL positive chronic myelogenous leukemia (CML) that quickly evolved to a blast crisis. We discuss the possible cause-effect mechanism between the previous treatment and CML, and suggest that a distinct mechanism, albeit unknown, could be involved in the development and progression of secondary CML.