Nodular localized cutaneous amyloidosis: further demonstration of monoclonality of infiltrating plasma cells in four additional Japanese patients.

Nodular localized cutaneous amyloidosis (NLCA) is a disorder characterized by deposition of amyloid derived from immunoglobulin light chains. We used semi-nested polymerase chain reaction (PCR) to analyse archival paraffin-embedded sections from a previous patient and from four additional, previously reported patients with NLCA to determine whether involvement of monoclonal plasma cells is a universal feature of this condition. The semi-nested PCR analysis revealed one or two amplified bands, around 100-120 bp, for all five cases of NLCA, although the yields varied from case to case. These results suggest that clonal expansion of plasma cells in NLCA may occur locally.