Pseudo-Gaucher cells in multiple myeloma.

A bone biopsy specimen from a patient with multiple myeloma showed numerous Gaucher-like cells scattered throughout a homogeneous background of plasma cells. Further studies using histochemical stains, immunofluorescence, and light and electron microscopy were carried out to further define these cells. Light microscopy of Wright-stained and hematoxylin and eosin-stained marrow preparations showed large, round cells with fibrillar appearing cytoplasm and eccentric, pyknotic nuclei. These cells were periodic acid-Schiff positive, resistant to diastase digestion. Electron microscopy demonstrated plasma cells containing crystals in membrane-bound vesicles. Also, large macrophages among these plasma cells contained similar crystals surrounded by a single limiting membrane. Immunofluorescence staining of thin sections of marrow with fluorescein-labelled specific antiserums showed fluorescence of these large cells. Strong immunofluorescence was seen with polyvalent kappa and gamma antiserums but not with anti-albumin or serums with anti-lambda, mu or alpha specificity. It appears that these large cells have the light microscopic and histochemical characteristics of true Gaucher cells but, when studied with immunofluorescence and electron microscopy, it appears that the pseudo-Gaucher cells of multiple myeloma are bone marrow macrophages engorged with immunoglobulin.