Ultrastructural characteristics of the plasma cells of a patient with nonsecretory myeloma and plasma cell leukemia.

The clinical features and the ultrastructural findings of the bone marrow and peripheral blood plasma cells of a patient with nonsecretory myeloma and acute plasma cell leukemia are described. The internal ultrastructure of the cells was characterized by invaginated nuclei, cytoplasmic filaments and scanty endoplasmic reticulum. Scanning electron microscopy examination revealed the presence of numerous membranal buddings giving the cells a grape-like appearance. The relationship of the morphological findings to the function of the plasma cells is discussed.