Multiple myeloma with hypogammaglobulinemia. Electron microscopic and chromosome studies

A case of multiple myeloma with hypogammaglobulinemia and absence of detectable light chain fragments in serum or urine was studied. Electron microscopy of myeloma cells in marrow revealed hypertrophied endoplasmic reticulum consistent with increased protein formation. Enzymatic dysfunction may have operated to inhibit completion of this process. Chromosome abnormalities in myeloma cells and peripheral leukocyte culture were consistent with neoplasia.