Primary localized amyloidosis of the eyelid: two cases of immunoglobulin light chain-derived proteins, subtype lambda V respectively lambda VI.

Primary localized amyloidosis has been described in many different organs in the body. Studies by immunohistochemical techniques have suggested an immunoglobulin light chain origin of the amyloid material. Only in a limited number of cases has the amyloid protein been characterized by amino acid sequence analysis as subtypes of immunoglobulin light chain or heavy chain. In this report, two cases of primary localized amyloidosis of the eyelid are presented. The amyloid substance has been extracted and a major fibril protein subjected to amino acid sequence analysis. Both amyloid proteins were part of the variable region of immunoglobulin light chains, subtype lambda V and subtype lambda VI, respectively. While lambda VI has been shown to be a common subtype in systemic immunoglobulin light chain-amyloidosis, it has never been demonstrated in localized amyloid. Very few lambda V immunoglobulin light chains have been characterized and the subgroup has never been found in amyloid before.