The ultrastructure of bone marrow plasma cells obtained from patients with multiple myeloma during the clinical course of the disease.

The ultrastructure of plasma cells from 65 consecutive bone marrow specimens from 13 patients with multiple myeloma is described. Biopsies were taken from 12 of the patients prior to and after initiation of treatment. The study was undertaken with the aim of correlating ultrastructural characteristics of the myeloma cells with biochemical and clinical parameters, including the survival time after treatment of the patients with cytostatics. Intranuclear inclusions were only seen in the cells of four patients, all of whom had rather long survival times. Two of these are still alive and, furthermore, their plasma cells are characterized by a low mean number of mitochondria in each sectioned cell studied, i.e. 7 and 14, respectively. Nuclear bodies were found in about 7 per cent of the plasma cells in biopsies taken before treatment was initiated. During treatment this percentage increased significantly to about 16 (2P = 0.004). A nuclear/cytoplasmic asynchrony was a characteristic feature of the ultrastructure of the myeloma cells. During treatment a significant increase from 34 to 54 per cent (2P = 0.03) was observed in the number of plasma cells with slight asynchrony. No correlation could be established between any ultrastructural features and the values obtained with clinical tests considered of major prognostic significance at the time of diagnosis, e.g. the concentrations of serum creatinine, haemoglobin, serum albumin and serum calcium.