Persistent malignant stem cells in del(5q) myelodysplasia in remission.
BACKGROUND: The in vivo clinical significance of malignant stem cells remains unclear. METHODS: Patients who have the 5q deletion (del[5q]) myelodysplastic syndrome (interstitial deletions involving the long arm of chromosome 5) have complete clinical and cytogenetic remissions in response to lenalidomide treatment, but they often have relapse. To determine whether the persistence of rare but dist