Lichen sclerosus (LS) is a chronic, inflammatory, mucocutaneous disorder of genital and extragenital skin. LS is a debilitating disease, causing itch, pain, dysuria and restriction of micturition, dyspareunia, and significant sexual dysfunction in women and men. Many findings obtained in recent years point more and more towards an autoimmune-induced disease in genetically predisposed patients and further away from an important impact of hormonal factors. Preceding infections may play a provocative part. The role for Borrelia is still controversial. Trauma and an occlusive moist environment may act as precipitating factors. Potent and ultrapotent topical corticosteroids still head the therapeutic armamentarium. Topical calcineurin inhibitors are discussed as alternatives in the treatment of LS in patients who have failed therapy with ultrapotent corticosteroids, or who have a contraindication for the use of corticosteroids. Topical and systemic retinoids may be useful in selected cases. Phototherapy for extragenital LS and photodynamic therapy for genital LS may be therapeutic options in rare cases refractory to the already mentioned treatment. Surgery is restricted to scarring processes leading to functional impairment. In men, circumcision is effective in the majority of cases, but recurrences are well described. Anogenital LS is associated with an increased risk for squamous cell carcinoma of the vulva or penis. This review updates the epidemiology, clinical presentation, histopathology, pathogenesis, and management of LS of the female and male genitals and extragenital LS in adults and children.

Ectodermal dysplasias are a large group of heritable conditions characterized by congenital defects of one or more ectodermal structures and their appendages: hair (hypotrichosis, partial, or total alopecia), nails (dystrophic, hypertrophic, abnormally keratinized), teeth (enamel defect or absent), and sweat glands (hypoplastic or aplastic). The ectodermal dysplasias, as a rule, are not pure "one-layer diseases." Mesodermal and, rarely, endodermal dysplasias coexist. Embryogenesis exhibits distinct tissue organizational fields and specific interactions among the germ layers that may lead to a wide range of ectodermal dysplasias when genes important for development are mutated or otherwise altered in expression. Of the approximately 200 different ectodermal dysplasias, about 30 have been studied at the molecular level with identification of the causative gene. Freire-Maia and Pinheiro used the clinical aspects for their classification, and Priolo integrated molecular genetic and clinical aspects for her scheme. Those two more historical classification schemes have the difficulty that, when applied strictly, several additional groups of diseases should be integrated within the term "ectodermal dysplasias," e.g. keratodermas with skin or hair alterations or the ichthyoses with associated features. Such consequent classification would lead to an endless list of diseases and would be useless for the practical work. Recent evidence implicates a genetic defect in different pathways orchestrating ectodermal organogenesis. Modern molecular genetics will increasingly elucidate the basic defects of the different syndromes and yield more insight into the regulatory mechanisms of embryology. In this way, a reclassification of ectodermal dysplasias will be possible according to the function of their involved mutated genes. Lamartine recently proposed a helpful classification according to the functions of the genes discovered in different types of ectodermal dysplasias. Accordingly, the present overview categorizes the various ectodermal dysplasias into four major functional subgroups: cell-cell communication and signaling, adhesion, transcription regulation, and development.

Skin color is highly individual and the variations are controlled by numerous genes. The different skin colors result from the size and number of melanosomes and do not mirror the amount of melanocytes. Disorders of pigmentation can result from migration abnormalities of melanocytes from the neural crest to the skin during embryogenesis. In addition, impairment of melanosome transfer to the surrounding keratinocytes, an alteration in melanin synthesis and a defective degradation or removal of melanin may lead to abnormal skin pigmentation. Immunologic or toxic mediated destructions of melanocytes can end in pigmentation disorders. Disorders of pigmentation are classified in hypo- or hyperpigmentation which can occur as a genetic or acquired disease. They can manifest locally or diffuse. Congenital hypopigmentation can be restricted to the skin as in piebaldism or they represent a systemic disease as in Menkes disease or phenylketonuria. Localized hypo- or hyperpigmentation in children may serve as markers for systemic diseases. Ash-leaf hypopigmentation are characteristic for tuberous sclerosis and more than 5 café-au-lait spots suggest neurofibromatosis 1 (von Recklinghausen disease). The most common autoimmune-induced depigmentation is vitiligo. Generalized hyperpigmentation only rarely reflects a primary genetic disorder but is most often from acquired diseases as in Addison disease, secondary hemochromatosis or primary biliary cirrhosis. Treatment of pigmentation disorders are based on a diagnosis which sometimes allow a specific intervention. Cosmetically acceptable results are difficult to obtain.

The palmoplantar skin is a highly specialized tissue which is able to resist mechanical trauma and other physical stress. In recent years the more descriptive classification of keratodermas has switched to an exact molecular genetic view where gene functions are considered. Palmoplantar keratodermas can be separated in the following functional subgroups: disturbed gene fuctions in structural proteins (keratins), cornified envelope (loricrin, transglutaminase), cohesion (plakophilin, desmoplakin, desmoglein1), cell-to-cell communication (connexins), and transmembrane signal transduction (cathepsin C). This review intends to emphasize the typical clinical aspects and symptom complexes associated with palmoplantar keratodermas which enable the astute dermatologist to make a clinical diagnosis. In addition the molecular genetic knowledge on the topic is given which is necessary to confirm the clinical diagnosis.

Hair dysplasias are congenital or acquired alterations which often involve the hair shaft. Hair shaft abnormalities are characterized by changes in color, density, length and structure. Hair shaft alterations often result from structural changes within the hair fibers and cuticles which may lead to brittle and uncombable hair. The hair of patients with hair shaft diseases feels dry and looks lusterless. Hair shaft diseases may occur as localized or generalized disorders. Genetic predisposition or exogenous factors produce and maintain hair shaft abnormalities. Hair shaft diseases are separated into those with and those without increased hair fragility. In general, optic microscopy and polarized light microscopy of hair shafts provide important clues to the diagnosis of isolated hair shaft abnormalities or complex syndromes. To establish an exact diagnosis of dysplastic hair shafts, a structured history and physical examination of the whole patient are needed which emphasizes other skin appendages such as the nails, sweat and sebaceous glands. Profound knowledge on hair biology and embryology is necessary to understand the different symptom complexes. Therapy of hair shaft disorders should focus on the cause. In addition, minimizing traumatic influences to hair shafts, such as drying hair with an electric dryer or permanent waves and dyes, is important. A short hairstyle is more suitable for patients with hair shaft disorders.