Chapter 123 : Skin Diseases

Abstract:

The dermis and epidermis have a dense network of adhesion proteins and fibrous structural proteins that provide mechanical strength to the skin. A number of these adhesion molecules are known to become targets of autoantibodies, and antigen-antibody interactions in the skin lead to the clinical manifestations of autoimmune bullous skin diseases. Demonstration of the characteristic autoantibodies in the tissue and circulating in the blood is the critical diagnostic feature of numerous such diseases. In most of these diseases, the circulating autoantibodies have also been shown, by passive transfer in animal models, to directly cause the characteristic tissue injury. For each of these diseases, this chapter describes the expected findings in tissue and serum and outlines immunochemical tests that may be useful in diagnosis. There are four major forms of pemphigus: pemphigus vulgaris (PV), pemphigus foliaceus (PF), paraneoplastic pemphigus (PNP), and IgA pemphigus. All forms are characterized by a loss of normal epidermal cell-to-cell adhesion (acantholysis) and by the presence of pathogenic autoantibodies reacting against desmosomal adhesion molecules. Pemphigus is a potentially lethal disease; to establish the diagnosis with certainty, the presence of both tissue-bound and circulating autoantibodies must be demonstrated.