Use of peripheral blood blasts vs bone marrow blasts for diagnosis of acute leukemia

Acute leukemia can be diagnosed when blasts constitute 30% or more of the n ucleated cells in a patient's peripheral blood (PB) sample. To determine wh ether in such cases bone marrow (BM) aspirates are still necessary, we comp ared the results of diagnostic studies performed on PB samples with blast c ounts of 30% or more with those performed on the same patients' BM samples. We found no differences in morphologic features, cytochemistry, or immunop henotype between the blasts in PB and BM samples in any of 30 cases studied However in 10 (23%) of 44 cases in which cytogenetic analysis was performe d, PB but not BM samples were insufficient for analysis. The converse never occurred Five of the 10 cases had acute lymphoblastic leukemia and 5 had a cute myeloid leukemia (41% of the patients with acute lymphoblastic leukemi a and 17% of the patients with acute myeloid leukemia). In cases with adequ ate metaphases, there was strong correlation between the cytogenetic result s for PB and BM samples. Some PB samples with blast counts of 30% or more a re adequate for diagnosis of acute leukemia, especially when therapy can be delayed until it is known that an adequate number of analyzable metaphases are recovered from the PB samples.