Cytogenetic evidence that the malignant event in multiple XXXX occurs in a precursor lymphocyte.

@entity1582 @entity1 @entity9865 @entity66
@entity1582 is traditionally thought of as a disease of plasma cells. Evidence from studies using antiodiotype antibodies, however, suggests that malignant events may take place in a precursor lymphocyte perhaps as early as the pre-B cell. In this study, we present cytogenetic evidence to support the latter view. Peripheral blood was obtained from a @entity1 with @entity9865 and @entity66 . Karyotypic analysis, using Giemsa banding techniques, showed an abnormal karyotype: 44,XY,-6,-8,-13,-16,-22,+mar1,+ mar2,+mar3,del(1)(p22,p32),11p+,13q+,14q+. A suspension culture was established and a plasma cell line was grown. It was characterized by transmission electron microscopy as having an eccentric nucleus, abundant cytoplasm, and extensive endoplasmic reticulum. A subculture of this line was subsequently grown that was characterized by transmission electron microscopy as a lymphoid cell with diminished quantity of cytoplasm without extensive endoplasmic reticulum. Karyotypic analysis of the smaller cell demonstrated a modal number of 88 chromosomes and was a tetraploid derivative of the first. Our study provides cytogenetic evidence that cells with a lymphocytic phenotype show karyotypic abnormalities seen in the malignant plasma cell of the same @entity1 , and thus, can be considered as evidence favoring the initiating cell of plasma cell @entity1582 as being an early B lymphocyte.
