Multiple myeloma and amyloidosis of the tongue.

Tongue biopsies of 30 diagnosed cases of multiple myeloma were examined light and electron microscopically and amyloid deposits were identified in 8 patients. Immunochemical typing of amyloid in kappa and lambda subtypes was performed successfully although positive staining of tissue-associated immunoglobulin light chains made reliable identification of amyloid with this technique difficult. Cells of macrophage lineage appear to play a central role in light chain-associated amyloidogenesis. Our findings do not agree with the reported higher amyloidogenic potential of lambda light chains and we were unable to show a positive correlation between the percentage plasma cells in bone marrow aspirates or the presence of urinary light chains and myeloma-associated amyloidosis.