Risk groups of myeloma patients by histologic pattern and proliferative activity.

We investigated the histologic pattern and the cell proliferative activity of myeloma cells by the analysis of the nucleolar organizer regions (AgNORs) in bone marrow biopsy specimens from 150 multiple myelomas at diagnosis. The objective was an attempt to define risk groups of myeloma patients. On univariate analysis, the percentage of bone marrow plasma cells (BMPC%), the pattern of infiltration, the degree of plasma cell (PC) atypia, the marrow fibrosis, and the number of AgNOR/PC were correlated with survival time. On multivariate analysis, only AgNOR counts and pattern of infiltration retained independent prognostic significance. At 4-year followup, all patients with BMPC% < or = 20, interstitial pattern of invasion, and well-differentiated (G1) PC plus AgNOR/cell < or = 3.32 were alive, while no patient with BMPC% >50, diffuse pattern of infiltration, and poorly differentiated (G3) PC plus AgNOR/cell >5.15 survived (p < 0.0001). In conclusion, the histologic pattern and proliferative activity of myeloma cells, evaluated by AgNOR counts, are reliable predictors of survival in myeloma. Both parameters can be easily assessed in the same biopsy specimen, are reproducible, and permit identification of a group of patients with favourable outcome at 4-year followup. Thus, bone marrow biopsy should always be included in the diagnostic procedures for myeloma patients.