Amyloid neuropathy: relationship between amyloid fibrils and macrophages.

A case of amyloid neuropathy associated with a multiple myeloma IgG light chain is reported. Under light microscopy the peripheral nerve exhibited several amyloid deposits. Electron microscopy revealed numerous amyloid deposits; at their periphery, macrophagic histiocytes were observed, containing a few tufts of parallel fibrils in their cytoplasm. A few plasma cells were scattered in the endoneurium and did not exhibit such a relationship. These findings resemble those recently observed in stem-cell cultures of IgG lambda chain human myeloma.