[Development of polycythemia vera during chronic idiopathic myelofibrosis]

A case of typical idiopathic myelofibrosis turning into polycythaemia vera 6 years after diagnosis is reported. This transformation occurred after treatment with busulphan. The present case is added to similar previous observations to give further support to the contention that the transition of chronic idiopathic myelofibrosis to polycythaemia vera may be a consequence, though rare, of therapy rather than a spontaneous event occurring during the course of the disease.