Simultaneous cell type identification and premature chromosome condensation analysis in a case of multiple myeloma.

The technique of premature chromosome condensation was combined with immunocytochemical techniques to determine the karyotype of the plasma cells in a patient with multiple myeloma. Although the patient's myeloma cells had a diploid DNA content, the mean chromosome number was 39. Multiple chromosome rearrangements were documented in the G- and C-banded G1 and G2 prematurely condensed chromosomes, and several of these involved telomeric regions resulting in dicentric chromosomes. That the aberrant karyotype was present in the kappa light chain positive plasma cells was proved by simultaneous chromosome analysis and immunocytochemical examination of the fused cells. Thus the combination of premature chromosome condensation and immunocytochemistry proved a powerful tool for cytogenetic analysis of a slow-growing, heterogeneous cell population.