Flow cytometry shows recurrent aneuploid clone after remission in megakaryocytic leukemia

Flow cytometry using a DNA label can quantitate aneuploid clones in malignant tissue. We illustrated the clinical value of this technique in a 71-year-old woman with acute megakaryocytic leukemia, which was diagnosed by staining of the blasts with factor VIII antigen and their morphologic resemblance to megakaryoblasts. Marrow cells were removed from needle biopsies by vortexing in RPMI medium, centrifuged in Ficoll-Hypaque, stained with a propidium-iodide/NP-40 mixture, and analyzed at 488 nm using an argon laser. During 3 weeks of low-dose cytosine arabinoside (ara-c) infusion therapy, hyperdiploid peak A dropped from 35% (day 0) to 2.3% (day 14) to 0% (day 21), with development of marrow hypoplasia. Similarly, hyperdiploid peak B, went from 7.6% to 9.1% to 3.5%. Subsequently, her marrow recovered normal morphology and lost the aneuploid peaks. Her blood counts recovered to near normal. Four months later, she relapsed and had a return of the day-21, incompletely eradicated peak B. There was no evidence of peak A. Repeated treatment with ara-c resulted in temporary suppression of the disease, but she died 3 months later with progressive hepatosplenomegaly. Analysis of cells from her enlarged liver, heavily infiltrated with blasts, showed a large hyperdiploid peak B. In this patient, ara-c therapy induced a remission with permanent eradication of one clone, but incomplete eradication of a second clone, which ultimately led to her relapse and death.