Plasmacytoid dendritic cells: an overview of their presence and distribution in different inflammatory skin diseases, with special emphasis on Jessner's lymphocytic infiltrate of the skin and cutaneous lupus erythematosus

Background: Plasmacytoid dendritic cells (PDC) play a pivotal role in the induction of autoimmune diseases and other skin diseases. The present study focuses on the distribution patterns of PDC in patients with cutaneous lupus erythematosus (LE) and Jessner's lymphocytic infiltrate (LI) of the skin and compares them with other skin diseases. The goal was to scrutinize the involvement of PDC in LI, and to show that PDC present a specific pattern of distribution in various cutaneous disorders. Methods: 353 skin biopsies of LE (various subtypes), LI, and other inflammatory skin diseases as well as two halo melanocytic nevi and 10 epithelial tumors were immunohistochemically investigated for the presence of PDC by employing antibodies against CD123 and CD2AP. Results: PDC were constantly detected as distinct perivascular and periadnexal clusters in LE and LI. In other forms of dermatitis, PDC could be found as single cells or scattered throughout the infiltrate or beneath the epidermis. Conclusions: Our data suggest that the distribution of PDC in tumid LE and LI is identical, and this observation suggests that both designations signify one disease. The distinct PDC arrangement in LE represents as useful diagnostic tool in the differential diagnosis with other forms of dermatitis. Tomasini D, Mentzel T, Hantschke M, Cerri A, Paredes B, Rütten A, Schärer L, Kutzner H. Plasmacytoid dendritic cells: an overview of their presence and distribution in different inflammatory skin diseases, with special emphasis on Jessner's lymphocytic infiltrate of the skin and cutaneous lupus erythematosus.