Peripheral blood cytogenetic studies in hematological neoplasms: predictors of obtaining metaphases for analysis

Peripheral blood (PB) is sometimes used in place of bone marrow (BM) for cytogenetic studies during the evaluation of hematologic malignancies. A total of 242 PB cytogenetic studies from adult patients were performed: clinical diagnosis was a myeloid neoplasm in 169 patients (70%), lymphoid or plasma cell neoplasm in 50 (21%), and a benign/reactive cytopenia or leukocytosis in 23 (9%). PB cytogenetic studies resulted in at least two analyzable metaphases in 142 of the 242 study cases (59%); in univariate analysis, this was predicted by the specific clinical diagnosis (P < 0.0001), presence and degree of circulating myeloid progenitor cells or blasts of any lineage (P < 0.0001), higher leukocyte count (P < 0.001), lower platelet count (P = 0.003), lower hemoglobin level (P = 0.002), and presence of palpable splenomegaly (P = 0.002). In multivariable analysis, only the presence of circulating myeloid progenitor cells or blasts sustained significance and this was consistent with the high yield rates seen in primary myelofibrosis (PMF) (80%), post-PV/ET PMF (85%), acute myeloid leukemia (76%), and acute lymphoblastic leukemia (80%) in contrast with the low rates seen in ET (0%) and PV (2%). In 104 cases, BM cytogenetic studies were performed within 1 month of the PB cytogenetic studies; an abnormal BM cytogenetic finding was another independent predictor of a successful PB study (P = 0.002). PB cytogenetic studies are most appropriate in diseases of adults characterized by presence of circulating myeloid progenitors or blasts; the yield otherwise is too small to be cost-effective.