Karyotypic evolution in multiple myeloma.

A patient with IgG kappa multiple myeloma was studied cytogenetically prior to therapy and was found to have a clone of 55,XX cells. After treatment leading to a clinical response, the patient relapsed with a clone of 57,XX cells, which were derivatives of the original neoplastic cell line. This is the first case of demonstrated clonal evolution of myeloma in a patient studied prior to chemotherapy.