Needle-shaped inclusions in plasma cells in a patient with hypogammaglobulinemia

A case of a patient with needle-shaped inclusions in plasma cells was reported. Some of the inclusions were positively stained for acid phosphatase and beta-glucuronidase. Ultrastructurally, each inclusion was surrounded by a single limiting membrane without any relation to rough-surfaced endoplasmic reticulum and composed of numerous fine fibrous bundles. By the enzyme-labeled antibody technic, the inclusions were found as "stain defects" in IgG-forming plasma cells, but not in IgM-forming plasma cells. Although the exact nature of the inclusions could not be clarified, they were quite different from both amyloid fibrils and immunoglobulin-derived inclusions, and were thought to be synthesized by a clone of differentiated plasma cells. The patient showed moderate hypogammaglobulinemia but no evidence of a direct correlation between the inclusions and hypogammaglobulinemia was obtained. Though the possibility that the case was non-secretory myeloma could not be ruled out, it was unlikely judged by the findings of various examinations.