Brain-restricted amyloidoma of immunoglobulin lambda-light chain origin clinically resembling multiple sclerosis

Cerebral amyloid deposits restricted to the white matter and associated with intracerebral lymphoma were biochemically identified. The patient died at 58 years of age after 37 years of illness with progressive neurological symptoms clinically indicative of multiple sclerosis. Pathomorphologically, spongiform alteration and demyelinization of the white matter in the vicinity of the amyloid deposits was detected and systemic amyloidosis excluded. Immunohistochemically, the amyloid was found to be of immunoglobulin lambda-light chain origin. To establish the nature of this amyloid, its fibrils were extracted and the amyloid fibril proteins isolated by size exclusion chromatography. Immunochemically, the purified amyloid fibril proteins were shown to be of immunoglobulin lambda-light chain origin. This finding was substantiated chemically. Since the N-terminal amino acid was blocked, tryptic peptides were isolated by reversed phase HPLC. The amino-acid sequence of two major peptides revealed homology with the variable region of the immunoglobulin lambda-light chain. This report defines a novel local A lambda-amyloid disease restricted to the white matter of the brain.