Peripheral Blood Cytogenetic Studies in Myelofibrosis: Overall Yield and Comparison with Bone Marrow Cytogenetic Studies

Background: Peripheral blood (PB) is sometimes used in place of bone marrow (BM) for cytogenetic studies in either primary (PMF) or post-polycythemia vera/essential thrombocythemia (post-PV/ET MF) myelofibrosis. In a retrospective study, we examined overall yield from PB cytogenetic studies in MF and where possible compared the results with those obtained by BM cytogenetic analysis.

Methods: Standard laboratory techniques were used to perform cytogenetic studies in both the PB and BM. A successful study constituted the acquisition of at least two analyzable metaphases and an abnormal clone required the presence of a specific cytogenetic abnormality in at least two metaphases. Clinical and laboratory correlations were made using variables collected at the time of cytogenetic studies.

Results I: A total of 242 PB cytogenetic studies were reviewed to identify 59 MF cases; 39 were PMF and 20 post-PV/ET MF. Median age was 60 years (range 36–77) and 37 were male patients. The median duration of the disease at the time of PB cytogenetic studies was 3.5 years (range 0.2–35). At least two analyzable metaphases (median 20, range 2–31) were obtained in 49 (81%) of the 59 study patients; in univariate analysis, this was predicted by presence and degree of circulating myeloid progenitor cells (p < 0.0001), higher PB CD34 count (p < 0.0001), higher leukocyte count (p = 0.0008), and absence of myeloid growth factor therapy (p = 0.005). In multivariable analysis, only the presence of circulating myeloid progenitor cells sustained its significance.

Results II: Twenty two cases had concomitant PB and BM cytogenetic studies performed. Of these, 9 patients had abnormal BM cytogenetic findings; the concomitant PB cytogenetic studies were also abnormal in 5 (56%) patients but normal in the other 4. Conversely, PB cytogenetic studies were abnormal in 12 patients; the concomitant BM cytogenetic studies were abnormal in 5 (41%) and normal in the remaining 7. PB cytogenetic studies were not successful in 4 of the 22 total cases; BM studies were successful in 3 of these 4 cases and the results were normal in all.

Conclusion: In the presence of circulating myeloid progenitor cells, PB can be considered as an alternative to BM for cytogenetic studies in MF patients, especially in view of the difficulty getting BM aspirates in this disease. However, considering the prognostic value of specific cytogenetic abnormalities in MF, the non-trivial discordance between the BM and PB cytogenetic findings, observed in the current study, warrants a prospective evaluation for further clarification.