title: Nonsecretory multiple myeloma. Immunohistologic and ultrastructural observations on two patients.
abstract: Two well documented examples of nonsecretory multiple myeloma were studied by electron microscopic and immunohistologic methods. In one case, repeat studies revealed no intracytoplasmic immunoglobulins, and the cells displayed a "plasmacytoid" appearance with poor development of rough endoplasmic reticulum and Golgi regions. In the other case, most cells contained intracytoplasmic immmunoglobulins of a monoclonal type and the ultrastructural appearance was that of cells actively engaged in protein synthesis. These findings and others in the literature suggest that myelomas without an M component can be separated into nonproducers and true nonsecretors of immunoglobulins. In one case, immunofluorescence of bone marrow smears with double labels demonstrated three different plasma cell populations: those producing either monoclonal immunoglobulins M (IgM) or A (IgA) and those synthesizing simultaneously IgM and IgM. Dual immunoglobulin production, although known to occur in myelomas with paraproteinemia, has not been previously documented in the nonsecretory variety.
mesh_terms: D001853:Bone Marrow / Q000473:pathology; D002467:Cell Nucleus / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000648:ultrastructure; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D010950:Plasma Cells / Q000648:ultrastructure
chemical_list: D007136:Immunoglobulins