Cytokeratin expression in lichen amyloidosus and macular amyloidosis

Aim To understand the role of epidermal cells in the pathogenesis of lichen amyloidosus (LA) and macular amyloidosis (MA). Methods We carried out immunohistochemical investigations on cytokeratins (CKs) in amyloid deposits in formalin-fixed and paraffin-embedded tissue specimens from eight persons with LA and 12 with MA. The primary antibodies of CK1-8 (AE3), CK10 (DEK-10), CK14 (LL002), CK17 (E3), CK18 (DC10), CK19 (KS19.1), CK5/6/18 (LP34) and CK8/18 (5D3) were used in the study. Results In amyloid deposits, immunoreactivity with only two monoclonal antibodies (CK1-8 and CK5/6/ 18) was observed in 14 cases (eight LA and six MA), confirming the hypothesis that epidermal cells participate in amyloid formation of LA and MA. Comments All of the CKs detected in amyloid deposits were basic type (type II). It seems plausible either that acidic CKs might be degraded faster than basic types in amyloidogenesis or that paraffin-embedded tissue specimens are less sensitive than frozen tissue sections. The results of our study suggest that when paraffinembedded specimens are investigated by immunohistochemical methods, CK5 antibody is useful in the diagnosis of LA and MA.