Alkaptonuria is a rare inherited genetic disease which is caused by a mutation in the HGD gene for the enzyme homogentisate 1,2-dioxygenase ; if a person inherits an abnormal copy from both parents, the body accumulates an intermediate substance called homogentisic acid in the blood and tissues. Homogentisic acid and its oxidized form alkapton are excreted in the urine, giving it an unusually dark color. The accumulating homogentisic acid causes damage to cartilage and heart valves, as well as precipitating as kidney stones and stones in other organs. Symptoms usually develop in people over 30 years old, although the dark discoloration of the urine is present from birth.
Nevus is a nonspecific medical term for a visible, circumscribed, chronic lesion of the skin or mucosa. The term originates from nævus, which is Latin for "birthmark"; however, a nevus can be either congenital or acquired. Common terms, including mole, birthmark, and beauty mark, are used to describe nevi, but these terms do not distinguish specific types of nevi from one another.
Calcinosis cutis is an uncommon condition marked by calcium buildup in the skin and subcutaneous tissues. Calcinosis cutis can range in intensity from little nodules in one area of the body to huge, crippling lesions affecting a vast portion of the body. Five kinds of the condition are typically distinguished: calciphylaxis, idiopathic calcification, iatrogenic calcification, dystrophic calcification, and metastatic calcification.
Hyperpigmentation is the darkening of an area of skin or nails caused by increased melanin.
Periorbital dark circles are dark blemishes around the eyes. There are many cause of this symptom, including heredity and bruising.
Melasma is a tan or dark skin discoloration. Melasma is thought to be caused by sun exposure, genetic predisposition, hormone changes, and skin irritation. Although it can affect anyone, it is particularly common in women, especially pregnant women and those who are taking oral or patch contraceptives or hormone replacement therapy medications.
Hydroquinone, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. It has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid. Substituted derivatives of this parent compound are also referred to as hydroquinones. The name "hydroquinone" was coined by Friedrich Wöhler in 1843.
Azelaic acid (AzA) is an organic compound with the formula HOOC(CH2)7COOH. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a precursor to diverse industrial products including polymers and plasticizers, as well as being a component of a number of hair and skin conditioners. AzA inhibits tyrosinase.
A lentigo is a small pigmented spot on the skin with a clearly defined edge, surrounded by normal-appearing skin. It is a harmless (benign) hyperplasia of melanocytes which is linear in its spread. This means the hyperplasia of melanocytes is restricted to the cell layer directly above the basement membrane of the epidermis where melanocytes normally reside. This is in contrast to the "nests" of multi-layer melanocytes found in moles. Because of this characteristic feature, the adjective "lentiginous" is used to describe other skin lesions that similarly proliferate linearly within the basal cell layer.
Cysteamine is an organosulfur compound with the formula HSCH2CH2NH2. A white, water-soluble solid, it contains both an amine and a thiol functional groups. It is often used as salts of the ammonium derivative [HSCH2CH2NH3]+ including the hydrochloride, phosphocysteamine, and the bitartrate.The intermediate pantetheine is broken down into cysteamine and pantothenic acid.
Skin whitening, also known as skin lightening and skin bleaching, is the practice of using chemical substances in an attempt to lighten the skin or provide an even skin color by reducing the melanin concentration in the skin. Several chemicals have been shown to be effective in skin whitening, while some have proven to be toxic or have questionable safety profiles. This includes mercury compounds which may cause neurological problems and kidney problems.
β-arbutin, also known by its International Nomenclature of Cosmetic Ingredients (INCI) name, arbutin, is a glycosylated derivative of hydroquinone. β-Arbutin is naturally present in the leaves and bark of a variety of plants, notably the bearberry plant, Arctostaphylos uva-ursi. Utilized as a biosynthetic active ingredient in topical treatments for skin lightening, β-arbutin is aimed at addressing hyperpigmentation issues. Its mechanism of action involves inhibiting the activity of tyrosinase, an essential enzyme for melanin synthesis in the human skin, thereby leading to a reduction in hyperpigmentation. It is important to distinguish β-arbutin from its structurally similar stereoisomer, α-arbutin, which exhibits similar effects in clinical applications.
Depigmentation is the lightening of the skin or loss of pigment. Depigmentation of the skin can be caused by a number of local and systemic conditions. The pigment loss can be partial or complete. It can be temporary or permanent.
Esoterica is an over-the-counter topical ointment applied to the skin for the purpose of lightening freckles, age spots, chloasma, melasma, and other skin discolorations due to a benign localized increase in the production of melanin. Esoterica may have other appropriate medical uses as determined by a physician.
Pigmentation disorders are disturbances of human skin color. There may be a loss or reduction, which may be related to loss of melanocytes or the inability of melanocytes to produce melanin or transport melanosomes correctly.
Photorejuvenation is a skin treatment that uses lasers, intense pulsed light, or photodynamic therapy to treat skin conditions and remove effects of photoaging such as wrinkles, spots, and textures. The process induces controlled wounds to the skin. This prompts the skin to heal itself, by creating new cells. This process—to a certain extent—removes the signs of photoaging. The technique was invented by Thomas L Roberts, III using CO2 lasers in the 1990s. Observed complications have included scarring, hyperpigmentation, acne, and herpes.
Kyrle disease is identified as a form of an acquired perforating disease. Other major perforating diseases are elastosis perforans serpiginosa and reactive perforating collagenosis. Recently, however, there is a controversy on categorizing Kyrle disease with perforating dermatosis or a subtype of acquired perforating collagenosis.
Postinflammatory hypopigmentation is a cutaneous condition characterized by decreased pigment in the skin following inflammation of the skin.
Oral pigmentation is asymptomatic and does not usually cause any alteration to the texture or thickness of the affected area. The colour can be uniform or speckled and can appear solitary or as multiple lesions. Depending on the site, depth, and quantity of pigment, the appearance can vary considerably.
α-arbutin, is a glycosylated hydroquinone, and an anomer of the naturally occurring arbutin. α-Arbutin is used in the cosmetic and pharmaceutical industries for its skin lightening effects, treatment of hyperpigmentation, and as a safer alternative to hydroquinone.
