Prolonged preleukemic phase of chronic myelogenous leukemia.

We report the detailed features of a unique case of a 33-year-old male in whom a large percentage of marrow (68%) and blood (31%) cells carried the Philadelphia chromosome by cytogenetics and FISH, as well as the p210 BCR-ABL transcript by RT-PCR, for 15 months prior to development of chronic myelogenous leukemia. The patient was closely followed throughout the preleukemic period with repeat blood and bone marrow analysis with no hematologic or pathologic evidence of leukemia, despite harboring a large number (65%) of Ph+ marrow cells. we report the detailed history of a 33-year-old male who carried a large number of BCR-ABL-positive cells in the marrow and blood for more than 15 months before finally presenting with classic chronic myelogenous leukemia. This study is unique in that it provides the most detailed documentation of the hematologic, pathologic, and cytogenetic features of the preleukemic phase of chronic myelogenous leukemia ever reported.