Amylase-producing multiple myeloma. Cytochemical, immunohistochemical and immunoelectron microscopic studies.

The first autopsy case of amylase-producing IgA-lambda-type multiple myeloma is described. Immunohistochemically, amylase and alpha and lambda chains of immunoglobulin were demonstrated in the cytoplasm of the myeloma cells. Secretion of amylase by cultured myeloma cells obtained from the patient's pleural effusion was clearly demonstrated by the starch film method. Immunoelectron microscopically, positive reaction products for amylase and the alpha chain of immunoglobulin were observed in the well developed endoplasmic reticulum. Since no secretory granules were observed, we postulated that the secretory process of amylase was not via the zymogen granules but via a mechanism similar to that for immunoglobulin.