DNA ANEUPLOIDY, INCREASED PROLIFERATION AND NUCLEAR-AREA OF PLASMA-CELLS IN MONOCLONAL GAMMOPATHY OF UNDETERMINED SIGNIFICANCE AND MULTIPLE-MYELOMA

DNA cytometric and morphometric parameters of plasma cells were determ ined in 73 multiple myelomas (MMs), 31 monoclonal gammopathies of unde termined significance (MGUS), 11 reactive plasmacytoses (RPs) and 33 c ases of normal bone marrow (NBM) using a TV-based static cytometer com bined with a computerized relocation stage. Neoplastic transformation was defined by either an aneuploid DNA profile, an increased prolifera tive fraction or an increased mean nuclear area of plasma cells. Using threshold values defined by mean values and variations of NBM and RP, 67/73 MMs were correctly classified as malignant (sensitivity, 92%), whereas all NBMs and RPs were classified as benign (specificity, 100%) . In MGUS, cytometric parameters of malignancy were detected in 19/31 cases (61%). Six 4.9 these cases developed MM after a median time of 4 .9 years (mean follow-up, 9.3 years). Another three cases with MGUS de veloped MMs without previous cytometric plasma cell aberrations. Cytom etric data from repeated measurements in MGUS progressing to to MM exh ibited perfect consistency over time concerning the presence or absenc e of cytometrically detected neoplastic transformation. Cytometric abe rrations seem to be frequently associated with neoplastic growth in mo noclonal plasma cell proliferations but do not predict clinically mali gnant behavior.