Karyotype in multiple myeloma and plasma cell leukaemia.

Between October 1988 and October 1991, 104 patients with multiple myeloma and 6 with plasma cell leukaemia were studied cytogenetically. Abnormal karyotypes were found in bone marrow cells of 33 patients (30%). Most pathological karyotypes were complex with numerous modal and structural anomalies. Numerical anomalies most frequently involved chromosome 11 and structural aberrations occurred most often in chromosomes 1, 11 and 14. The most consistent structural aberration was a 14q+ chromosome (10 patients) resulting from a t(11;14)(q13;q32) in 4 patients and a t(8;14)(q24;q32) in 1 patient. Sequential cytogenetic studies were performed in 15 patients. In 5 of 8 cases with a normal karyotype at diagnosis, chromosomal anomalies were detected when disease progressed. In concomitant cytogenetic/cytological studies it was found that in the majority of patients with normal karyotype the mitoses originated from contaminating normal bone marrow cells. Pathological karyotypes were detected more frequently in pretreated than in untreated patients, in patients with plasma cell leukaemia than in patients with multiple myeloma, in patients with stage III and dense bone marrow infiltration than in patients with stage I. Patients with abnormal karyotype, irrespective if pretreated or not, had a significantly shorter median survival than those with normal karyotype. These findings suggest that karyotype is an independent prognostic factor in multiple myeloma.