Electron microscopic observation of inclusion bodies in plasma cells of multiple myeloma and Waldenström's macroglobulinemia.

Intracellular inclusion bodies in the plasma cells were sought by electron microscopy in 32 cases of multiple myeloma and 3 of Waldenström's macroglobulinemia. In some cases, round shaped intranuclear inclusions and intranuclear fibrillar bundles were observed. In other cases, Russell bodies and crystalline structures were found in the cisternae of rough surfaced endoplasmic reticulum (rER), and dense bodies, myelin-like structures, fibrillar formations, polysome lamellae complexes, crystalline structures, virus-like particles and phagocytosis were observed in the cytoplasm of plasma cells. The detailed ultrastructure of these inclusions was described, and their functional significance, origin and appearance rate were discussed. Finally, the presence of true viral particles in the plasma cells was ruled out.