Cerebral immunoglobulin light chain amyloid angiopathy-related hemorrhages

Cerebral amyloid angiopathy (CAA) is a common cause of intracerebral hemorrhage (ICH) particularly in elderly patients. In CAA-related hemorrhages, amyloid deposits in the brain vessel walls mainly contain amyloid beta-protein (A-beta). Rarely other forms of amyloid substances have been reported in sporadic CAA-related hemorrhages.

We report the case of a 44-year-old patient with recurrent ICH who had surgical evacuation of a large frontal hematoma. Following surgery, samples from the hematoma and adjacent cerebral cortex were obtained for histopathological examination.

Within the recent hemorrhage, a few arteriolar walls were thickened with an amyloid deposit that was immunostained for immunoglobulin (Ig) M and light chain lambda. In the wall of some vessels, around the amyloid deposits, as well as in the adjacent cerebral cortex, there was an infiltration by monotypic lymphocytes and plasma cells expressing IgM and light chain lambda. No amyloid deposition was found outside the hemorrhage. There was no evidence of multiple myeloma, B-cell malignancy, or systemic amyloidosis.

Recurrent ICH may be due to amyloid deposition of IgM lambda produced by monotypic proliferation of lymphocytes and plasma cells purely localized to the brain.