An unusual case of extramedullary blast crisis in chronic myelocytic leukaemia.

A 27-year-old man with chronic myelocytic leukaemia sustained two episodes of extramedullary blast transformation. The first episode was a lymphoblastic transformation in his cervical lymph nodes, which was treated and in remission for 15 months when a second blastic transformation occurred in the meninges. All the while, the bone marrow was free from blastic crisis.