Multiple myeloma is a disease with variable natural history, but a clinical fact is that most of the transplanted patients relapse early after transplantation. Minimal residual disease should be one prognostic factor of transplanted patients that could judge if such patients are at risk for early relapse. We diagnosed 50 multiple myeloma cases from 2450 oncohematologic cancer diseases studied between September 1993 and August 2004 (2% of all cases). Until 2000 these cases were studied using a Coulter Flow Cytometer XL-MCL with monoclonal antibodies against CD19, CD38, CD45, CD56, intra-cytoplasmatic and surface kappa and lambda in a Forward Scatter x Side Scatter gate strategy. After 2001 we performed sequential studies using CD138 histogram complexity and monoclonal antibodies anti CD19, CD38, CD56, CD117, intra-cytoplasmatic kappa and lambda. More recently we included in the antibody pool anti-CD45, anti-HLA-DR and anti-CD33. DNA cytometric studies were performed with the Multicycle software in 9 cases, 7 of those with aneuploidy. G band karyotyping was made in 25 cases and the 13 q deletion was checked in 15 cases. Chromosomal alterations were found in 4 cases including two 13 q deletions, confirmed by FISH. Gate choice, cytogenetic studies and cycle kinetics of DNA are all data that permit better identification of anomalous plasma cells and therefore detection of minimal residual disease, that probably correlates with relapse prognosis.
Multiple myeloma; flow cytometry; cytogenetics; minimal residual disease detection
