Nonsecretory myelomatosis without intracellular immunoglobulin. Immunofluorescent and ultramicroscopic studies.

A patient with multiple myeloma is reported with severe hypogammaglobulinaemia but without monoclonal immunoglobulin (M-component) in the serum or Bence Jones protein in the urine. In May-Grünwald-Giemsa stained bone marrow film 45% of the cells resembled plasma cells. Marrow immunofluorescent studies showed no increase of immunoglobulin containing cells. Ultrastructural studies showed a large number of cells with a well developed rough endoplasmic reticulum and other morphological features characteristic for plasma cells.