Intracerebral A lambda amyloidoma diagnosed by stereotactic biopsy.

In a 70-year-old patient with an intracerebral tumor, the very rare diagnosis of an A lambda amyloidoma has been made by stereotactic biopsy using immunohistochemistry with a panel of antibodies directed against amyloid fibril proteins of various origins. The production by an apparent benign monoclonal plasma cell proliferation with secretion of paraproteins into the cerebrospinal fluid is assumed. It is the 4th case in which the amyloid protein was classified as derived from immunoglobulin lambda-light chains and, to our knowledge the first in which an A lambda amyloidoma has been diagnosed intra vitam. The amyloid is restricted to the brain and no systemic involvement has been detected. Therapeutic procedures are discussed.