Electron microscopic analysis of myeloma cells in relation to drug response and prognosis

Myeloma cells obtained from 33 patients were analyzed by electron microscopy to determine whether there is any correlation among ultrastructural characteristics of myeloma cells, drug response, and prognosis. The median survival time after diagnosis of responders (18 cases) and nonresponders (15 cases) was more than 423 days and 139 days, respectively. Nuclear immaturity and three cytoplasmic abnormalities--scattered pattern of mitochondria, single-sac looplike structures, and numerous intramitochondrial granules--were found to be associated with poor outcome. Although the cytoplasm of almost all the myeloma cells examined was judged to be mature or intermediate, the degree of nuclear immaturity was considered to correspond closely to the grade of nuclear-cytoplasmic asynchrony. Thus the electron microscopic examination of myeloma cells is of use to assess accurately their immaturity and abnormality and might provide clues for the prediction of drug response and prognosis of individual patients.