96 - Perforating Diseases

Abstract

The perforating diseases are a group of disorders in which papulonodules develop due to transepidermal elimination of connective tissue or other substances. Two prototypes are reactive perforating collagenosis (RPC), in which collagen is the primary extruded material, and elastosis perforans serpiginosa (EPS), in which elastic tissue is involved. RPC and EPS may be inherited, but are more often acquired and related to an inciting condition. Kyrle disease is a third form of perforating disease and is related to perforation of nonspecific connective tissue; it is closely related to prurigo nodularis. Collectively, acquired perforating dermatosis, regardless of any subclassification as acquired RPC or Kyrle disease, is most often related to diabetes mellitus and/or chronic kidney disease (stages 4–5), with pruritus leading to prurigo lesions and connective tissue perforation through the epidermis. EPS can be related to long-term penicillamine administration as well as a number of genetic disorders, e.g. Marfan syndrome, Ehlers–Danlos syndrome. Keratotic plugs are common to all perforating disorders, both clinically and histologically. Lesions are often arranged in an annular pattern in EPS while a linear pattern due to the Koebner phenomenon is most commonly observed in RPC. Perforating folliculitis is often cited as the fourth major perforating disease, but in reality it is no different than any generic folliculitis in which the hair follicle has ruptured. Perforating disorders are difficult to treat, and various destructive methods are most commonly employed, such as curettage or cryotherapy. When there is extensive disease, phototherapy may be helpful.