Drawback of chimerism analysis by XY-fluorescence in situ hybridization: Deception of a relapse

Abstract

Chimerism is monitored by various methods in posttransplant patients. Interphase fluorescence in situ hybridization (FISH) for XY (sex) chromosomes is one of the methods commonly employed. It is a sensitive method in terms of the number of cells analyzed. Chimerism testing is done to detect graft rejection/failure which eventually may be a sign of relapse of the malignancy. The relapse of the disease initially happens in the marrow and then spreads to the peripheral blood. Hence, performing chimerism by XY-FISH in the peripheral blood may miss an early relapse. Here, we present one such case where there was 98% donor chimerism with the evidence of relapse in the bone marrow with all recipient metaphases in the bone marrow by conventional cytogenetics.

Keywords

• chimerism
• posttransplant monitoring
• xy-fluorescence in situ hybridization