Mast cell disease followed by leukemia with clonal evolution.

A 29-yr old woman developed urticaria pigmentosa which subsequently progressed through systemic mastocytosis to Philadelphia chromosome negative (Ph neg) chronic myelogenous leukemia (CML) with t(8;17). Further cytogenetic evolution occurred at the time of transformation to the aggressive phase of the disease. Unlike Ph-positive CML, chromosome number 9 was not involved, nor was the breakpoint cluster region located at band 22q11. This clearly separates this case from other Ph-negative CML patients who do have involvement of 9q34 or the breakpoint cluster region. Since this is the first case of its type to be reported with cytogenetic abnormalities, the clinical relevance of the unique chromosomal rearrangement t(8;17)(p11;q25) in the setting of systemic mastocytosis is unclear. Additional cases need to be reported to determine if this genetic rearrangement is a nonrandom marker of leukemia evolving in a setting of malignant mast cell disease.