Recurrence of acute leukemia in donor cells after bone marrow transplantation: documentation by in situ DNA hybridization.

Donor cell leukemia after BMT has been documented in a small number of cases mainly by cytogenetic studies. We describe a case of leukemia relapse in a 16-year-old girl 1 year after BMT from her histocompatible brother. Relapse in donor cells was initially suspected on the basis of cytogenetic analysis and confirmed by DNA in situ hybridization in blast cells using a Y chromosome-specific probe.