Clinical and prognostic features of patients with Philadelphia chromosome-positive chronic myelogenous leukemia and extramedullary disease.

Twenty-four patients who developed extramedullary disease during the course of Philadelphia chromosome-positive chronic myelogenous leukemia are described. The most frequent sites of extramedullary disease were lymph nodes (54%), bone (37%), and skin and soft tissue (29%). The appearance of extramedullary disease was associated with a high incidence of other features of accelerated disease (37%) and with cytogenetic clonal evolution (62.5%). The median time from extramedullary disease to blastic crisis was 4 months, and the median survival was 5 months. At the time of analysis, 23 patients have died, 16 after evolving into blastic crisis, and 7 from progressive disease without satisfying the criteria of medullary blastic crisis. This study confirms the importance of extramedullary disease as a sign of poor prognosis in chronic myelogenous leukemia, and the need for alternate therapies when such an event develops.