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
