Lichen Planus: An inflammatory, pruritic disease of the skin and mucous membranes, which can be either generalized or localized. It is characterized by distinctive purplish, flat-topped papules having a predilection for the trunk and flexor surfaces. The lesions may be discrete or coalesce to form plaques. Histologically, there is a "saw-tooth" pattern of epidermal hyperplasia and vacuolar alteration of the basal layer of the epidermis along with an intense upper dermal inflammatory infiltrate composed predominantly of T-cells. Etiology is unknown.Lichen Planus, Oral: Oral lesions accompanying cutaneous lichen planus or often occurring alone. The buccal mucosa, lips, gingivae, floor of the mouth, and palate are usually affected (in a descending order of frequency). Typically, oral lesions consist of radiating white or gray, velvety, threadlike lines, arranged in a reticular pattern, at the intersection of which there may be minute, white, elevated dots or streaks (Wickham's striae). (Jablonski, Illustrated Dictionary of Dentistry)Lichens: Any of a group of plants formed by a symbiotic combination of a fungus with an algae or CYANOBACTERIA, and sometimes both. The fungal component makes up the bulk of the lichen and forms the basis for its name.Lichenoid Eruptions: Conditions in which there is histological damage to the lower epidermis along with a grouped chronic inflammatory infiltrate in the papillary dermis disturbing the interface between the epidermis and dermis. LICHEN PLANUS is the prototype of all lichenoid eruptions. (From Rook et al., Textbook of Dermatology, 4th ed, p398)Acitretin: An oral retinoid effective in the treatment of psoriasis. It is the major metabolite of ETRETINATE with the advantage of a much shorter half-life when compared with etretinate.Vulvar Lichen Sclerosus: Atrophy and shriveling of the SKIN of the VULVA that is characterized by the whitish LICHEN SCLEROSUS appearance, inflammation, and PRURITUS.Mouth Mucosa: Lining of the ORAL CAVITY, including mucosa on the GUMS; the PALATE; the LIP; the CHEEK; floor of the mouth; and other structures. The mucosa is generally a nonkeratinized stratified squamous EPITHELIUM covering muscle, bone, or glands but can show varying degree of keratinization at specific locations.Lichen Sclerosus et Atrophicus: A chronic inflammatory mucocutaneous disease usually affecting the female genitalia (VULVAR LICHEN SCLEROSUS) and BALANITIS XEROTICA OBLITERANS in males. It is also called white spot disease and Csillag's disease.Keratolytic Agents: Agents that soften, separate, and cause desquamation of the cornified epithelium or horny layer of skin. They are used to expose mycelia of infecting fungi or to treat corns, warts, and certain other skin diseases.Tongue DiseasesHyperpigmentation: Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance.Clobetasol: A derivative of PREDNISOLONE with high glucocorticoid activity and low mineralocorticoid activity. Absorbed through the skin faster than FLUOCINONIDE, it is used topically in treatment of PSORIASIS but may cause marked adrenocortical suppression.Leukoplakia, Oral: A white patch seen on the oral mucosa. It is considered a premalignant condition and is often tobacco-induced. When evidence of Epstein-Barr virus is present, the condition is called hairy leukoplakia (LEUKOPLAKIA, HAIRY).Tolonium Chloride: A phenothiazine that has been used as a hemostatic, a biological stain, and a dye for wool and silk. Tolonium chloride has also been used as a diagnostic aid for oral and gastric neoplasms and in the identification of the parathyroid gland in thyroid surgery.Mouth DiseasesKeratosis: Any horny growth such as a wart or callus.Fluocortolone: A glucocorticoid with anti-inflammatory activity used topically for various skin disorders.Vulvar Diseases: Pathological processes of the VULVA.Mouth Neoplasms: Tumors or cancer of the MOUTH.Gingivitis, Necrotizing Ulcerative: An acute or chronic GINGIVITIS characterized by redness and swelling, NECROSIS extending from the interdental papillae along the gingival margins, PAIN; HEMORRHAGE, necrotic odor, and often a pseudomembrane. The condition may extend to the ORAL MUCOSA; TONGUE; PALATE; or PHARYNX. The etiology is somewhat unclear, but may involve a complex of FUSOBACTERIUM NUCLEATUM along with spirochetes BORRELIA or TREPONEMA.Lip DiseasesLichen Nitidus: A chronic inflammatory disease characterized by shiny, flat-topped, usually flesh-colored micropapules no larger than the head of a pin. Lesions are localized in the early stages, found chiefly on the lower abdomen, penis, and inner surface of the thighs. Distribution may become generalized as the disease progresses.Hand DermatosesStomatitis, Aphthous: A recurrent disease of the oral mucosa of unknown etiology. It is characterized by small white ulcerative lesions, single or multiple, round or oval. Two to eight crops of lesions occur per year, lasting for 7 to 14 days and then heal without scarring. (From Jablonski's Dictionary of Dentistry, 1992, p742)PUVA Therapy: Photochemotherapy using PSORALENS as the photosensitizing agent and ultraviolet light type A (UVA).Hematoxylin: A dye obtained from the heartwood of logwood (Haematoxylon campechianum Linn., Leguminosae) used as a stain in microscopy and in the manufacture of ink.Neurodermatitis: An extremely variable eczematous skin disease that is presumed to be a response to prolonged vigorous scratching, rubbing, or pinching to relieve intense pruritus. It varies in intensity, severity, course, and morphologic expression in different individuals. Neurodermatitis is believed by some to be psychogenic. The circumscribed or localized form is often referred to as lichen simplex chronicus.Gingival DiseasesMelanosis: Disorders of increased melanin pigmentation that develop without preceding inflammatory disease.Phototherapy: Treatment of disease by exposure to light, especially by variously concentrated light rays or specific wavelengths.Leukoplakia: A white patch lesion found on a MUCOUS MEMBRANE that cannot be scraped off. Leukoplakia is generally considered a precancerous condition, however its appearance may also result from a variety of HEREDITARY DISEASES.Skin DiseasesDermatitis: Any inflammation of the skin.Eosine Yellowish-(YS): A versatile red dye used in cosmetics, pharmaceuticals, textiles, etc., and as tissue stain, vital stain, and counterstain with HEMATOXYLIN. It is also used in special culture media.Anetoderma: Benign DERMATOSIS caused by a loss of dermal ELASTIC TISSUE resulting in localized sac-like areas of flaccid skin. It can be either primary (idiopathic) or secondary to other skin conditions, PENICILLAMINE use, or premature birth.Precancerous Conditions: Pathological processes that tend eventually to become malignant. (From Dorland, 27th ed)Burning Mouth Syndrome: A group of painful oral symptoms associated with a burning or similar sensation. There is usually a significant organic component with a degree of functional overlay; it is not limited to the psychophysiologic group of disorders.Administration, Topical: The application of drug preparations to the surfaces of the body, especially the skin (ADMINISTRATION, CUTANEOUS) or mucous membranes. This method of treatment is used to avoid systemic side effects when high doses are required at a localized area or as an alternative systemic administration route, to avoid hepatic processing for example.Photosensitivity Disorders: Abnormal responses to sunlight or artificial light due to extreme reactivity of light-absorbing molecules in tissues. It refers almost exclusively to skin photosensitivity, including sunburn, reactions due to repeated prolonged exposure in the absence of photosensitizing factors, and reactions requiring photosensitizing factors such as photosensitizing agents and certain diseases. With restricted reference to skin tissue, it does not include photosensitivity of the eye to light, as in photophobia or photosensitive epilepsy.Periodic Acid-Schiff Reaction: A histochemical technique for staining carbohydrates. It is based on PERIODIC ACID oxidation of a substance containing adjacent hydroxyl groups. The resulting aldehydes react with Schiff reagent to form a colored product.Foot Dermatoses: Skin diseases of the foot, general or unspecified.Stomatitis: INFLAMMATION of the soft tissues of the MOUTH, such as MUCOSA; PALATE; GINGIVA; and LIP.Hair Removal: Methods used to remove unwanted facial and body hair.Flatfoot: A condition in which one or more of the arches of the foot have flattened out.