Karyotypic patterns in chronic myeloproliferative disorders: report on 74 cases and review of the literature.

During the 15 year period 1975-1989, 74 cases of chronic myeloproliferative disorder (CMPD) were cytogenetically analyzed in our department. Thirty patients had polycythemia vera (PV), 23 had idiopathic myelofibrosis (MFS), 15 had idiopathic thrombocythemia (IT), and six had unclassifiable CMPD (UCMPD). The overall frequency of clonal chromosome aberrations was 36% (50% in PV, 30% in MFS, 27% in IT, and 17% in UCMPD). The frequency was markedly higher (53%) in the subset of patients who had received myelosuppressive therapy and/or had developed acute leukemia prior to the initial cytogenetic analysis. The pattern of the chromosome rearrangements in our series is in agreement with the karyotypic findings in the 411 previously reported cases of CMPD. Trisomy 8 and 9 and del(20q) dominate in PV. The picture in MFS is more heterogenous with several aberrations, dup(1q), -5, del(5q), -7, del(7q), +8, +9, del(13q), del(20q), and +21, found equally frequently. No pathognomonic chromosome aberration has been detected in IT, but t(9;22) occurs more often than other changes. Thus, although a non-random cytogenetic pattern is discernible in CMPD, there is considerable overlap both with other myeloid malignancies and among the different CMPD subtypes.