Testicular relapse of acute promyelocytic leukemia after allogeneic BMT.

After treatment of acute leukemia (typically ALL and the monocytic variants of AML), relapse may occur at sites other than the marrow. Isolated extramedullary relapse of acute promyelocytic leukemia (APL) however, is rare. We describe such an event in a man who underwent allogeneic BMT for APL in second relapse and 4 years later presented with testicular relapse. The marrow was morphologically and cytogenetically normal, but RT-PCR analysis revealed the specific PML/RAR chimeric RNA transcript.