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Nevus: A circumscribed stable malformation of the skin and occasionally of the oral mucosa, which is not due to external causes and therefore presumed to be of hereditary origin.Nevus of Ota: A macular lesion on the side of the FACE, involving the CONJUNCTIVA and EYELIDS, as well as the adjacent facial skin, SCLERA; OCULOMOTOR MUSCLES; and PERIOSTEUM. Histological features vary from those of a MONGOLIAN SPOT to those of a BLUE NEVUS.Nevus, Sebaceous of Jadassohn: A syndrome characterized by lesions occurring on the face, scalp, or neck which consist of congenital hypoplastic malformations of cutaneous structures and which over time undergo verrucous hyperplasia. Additionally it is associated with neurological symptoms and skeletal, ophthalmological, urogenital, and cardiovascular abnormalities.Dysplastic Nevus Syndrome: Clinically atypical nevi (usually exceeding 5 mm in diameter and having variable pigmentation and ill defined borders) with an increased risk for development of non-familial cutaneous malignant melanoma. Biopsies show melanocytic dysplasia. Nevi are clinically and histologically identical to the precursor lesions for melanoma in the B-K mole syndrome. (Stedman, 25th ed)Nevus, Intradermal: A nevus in which nests of melanocytes are found in the dermis, but not at the epidermal-dermal junction. Benign pigmented nevi in adults are most commonly intradermal. (Stedman, 25th ed)Synovitis, Pigmented Villonodular: Outgrowths of synovial membrane composed of villi and fibrous nodules characterized histologically by hemosiderin- and lipid-containing macrophages and multinucleated giant cells. It usually occurs in the knee.Nevus, Epithelioid and Spindle Cell: A benign compound nevus occurring most often in children before puberty, composed of spindle and epithelioid cells located mainly in the dermis, sometimes in association with large atypical cells and multinucleate cells, and having a close histopathological resemblance to malignant melanoma. The tumor presents as a smooth to slightly scaly, round to oval, raised, firm papule or nodule, ranging in color from pink-tan to purplish red, often with surface telangiectasia. (Dorland, 27th ed)Nevus, Pigmented: A nevus containing melanin. The term is usually restricted to nevocytic nevi (round or oval collections of melanin-containing nevus cells occurring at the dermoepidermal junction of the skin or in the dermis proper) or moles, but may be applied to other pigmented nevi.Skin Neoplasms: Tumors or cancer of the SKIN.Dermoscopy: A noninvasive technique that enables direct microscopic examination of the surface and architecture of the SKIN.Nevus, Halo: A benign skin lesion characterized by a zone of depigmentation surrounding the nevus.Pigmentation DisordersMelanoma: A malignant neoplasm derived from cells that are capable of forming melanin, which may occur in the skin of any part of the body, in the eye, or, rarely, in the mucous membranes of the genitalia, anus, oral cavity, or other sites. It occurs mostly in adults and may originate de novo or from a pigmented nevus or malignant lentigo. Melanomas frequently metastasize widely, and the regional lymph nodes, liver, lungs, and brain are likely to be involved. The incidence of malignant skin melanomas is rising rapidly in all parts of the world. (Stedman, 25th ed; from Rook et al., Textbook of Dermatology, 4th ed, p2445)Pigmentation: Coloration or discoloration of a part by a pigment.Albinism: General term for a number of inherited defects of amino acid metabolism in which there is a deficiency or absence of pigment in the eyes, skin, or hair.Lentigo: Small circumscribed melanoses resembling, but differing histologically from, freckles. The concept includes senile lentigo ('liver spots') and nevoid lentigo (nevus spilus, lentigo simplex) and may also occur in association with multiple congenital defects or congenital syndromes (e.g., Peutz-Jeghers syndrome).Skin Pigmentation: Coloration of the skin.Basal Cell Nevus Syndrome: Hereditary disorder consisting of multiple basal cell carcinomas, odontogenic keratocysts, and multiple skeletal defects, e.g., frontal and temporoparietal bossing, bifurcated and splayed ribs, kyphoscoliosis, fusion of vertebrae, and cervicothoracic spina bifida. Genetic transmission is autosomal dominant.Facial NeoplasmsMelanins: Insoluble polymers of TYROSINE derivatives found in and causing darkness in skin (SKIN PIGMENTATION), hair, and feathers providing protection against SUNBURN induced by SUNLIGHT. CAROTENES contribute yellow and red coloration.Hair Color: Color of hair or fur.Pigment Epithelium of Eye: The layer of pigment-containing epithelial cells in the RETINA; the CILIARY BODY; and the IRIS in the eye.Iris Neoplasms: Tumors of the iris characterized by increased pigmentation of melanocytes. Iris nevi are composed of proliferated melanocytes and are associated with neurofibromatosis and malignant melanoma of the choroid and ciliary body. Malignant melanoma of the iris often originates from preexisting nevi.Hyperpigmentation: 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.Scalp: The outer covering of the calvaria. It is composed of several layers: SKIN; subcutaneous connective tissue; the occipitofrontal muscle which includes the tendinous galea aponeurotica; loose connective tissue; and the pericranium (the PERIOSTEUM of the SKULL).Choroid Neoplasms: Tumors of the choroid; most common intraocular tumors are malignant melanomas of the choroid. These usually occur after puberty and increase in incidence with advancing age. Most malignant melanomas of the uveal tract develop from benign melanomas (nevi).Eye Color: Color of the iris.Melanocytes: Mammalian pigment cells that produce MELANINS, pigments found mainly in the EPIDERMIS, but also in the eyes and the hair, by a process called melanogenesis. Coloration can be altered by the number of melanocytes or the amount of pigment produced and stored in the organelles called MELANOSOMES. The large non-mammalian melanin-containing cells are called MELANOPHORES.Hamartoma: A focal malformation resembling a neoplasm, composed of an overgrowth of mature cells and tissues that normally occur in the affected area.Ciliary Body: A ring of tissue extending from the scleral spur to the ora serrata of the RETINA. It consists of the uveal portion and the epithelial portion. The ciliary muscle is in the uveal portion and the ciliary processes are in the epithelial portion.Keratosis, Seborrheic: Benign eccrine poromas that present as multiple oval, brown-to-black plaques, located mostly on the chest and back. The age of onset is usually in the fourth or fifth decade.Adrenal Cortex Diseases: Pathological processes of the ADRENAL CORTEX.Pigments, Biological: Any normal or abnormal coloring matter in PLANTS; ANIMALS or micro-organisms.Retinal Pigment Epithelium: The single layer of pigment-containing epithelial cells in the RETINA, situated closely to the tips (outer segments) of the RETINAL PHOTORECEPTOR CELLS. These epithelial cells are macroglia that perform essential functions for the photoreceptor cells, such as in nutrient transport, phagocytosis of the shed photoreceptor membranes, and ensuring retinal attachment.Sunlight: Irradiation directly from the sun.Hutchinson's Melanotic Freckle: A cellular subtype of malignant melanoma. It is a pigmented lesion composed of melanocytes occurring on sun-exposed skin, usually the face and neck. The melanocytes are commonly multinucleated with a "starburst" appearance. It is considered by many to be the in situ phase of lentigo maligna melanoma.Conjunctival Neoplasms: Tumors or cancer of the CONJUNCTIVA.Hemangioma: A vascular anomaly due to proliferation of BLOOD VESSELS that forms a tumor-like mass. The common types involve CAPILLARIES and VEINS. It can occur anywhere in the body but is most frequently noticed in the SKIN and SUBCUTANEOUS TISSUE. (from Stedman, 27th ed, 2000)Porokeratosis: A heritable disorder of faulty keratinization characterized by the proliferation of abnormal clones of KERATINOCYTES and lesions showing varying atrophic patches surrounded by an elevated, keratotic border. These keratotic lesions can progress to overt cutaneous neoplasm. Several clinical variants are recognized, including porokeratosis of Mibelli, linear porokeratosis, disseminated superficial actinic porokeratosis, palmoplantar porokeratosis, and punctate porokeratosis.Skin DiseasesIris Diseases: Diseases, dysfunctions, or disorders of or located in the iris.Carcinoma, Basal Cell: A malignant skin neoplasm that seldom metastasizes but has potentialities for local invasion and destruction. Clinically it is divided into types: nodular, cicatricial, morphaic, and erythematoid (pagetoid). They develop on hair-bearing skin, most commonly on sun-exposed areas. Approximately 85% are found on the head and neck area and the remaining 15% on the trunk and limbs. (From DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1471)Retina: The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.Sunburn: An injury to the skin causing erythema, tenderness, and sometimes blistering and resulting from excessive exposure to the sun. The reaction is produced by the ultraviolet radiation in sunlight.Melanosis: Disorders of increased melanin pigmentation that develop without preceding inflammatory disease.Eccrine Glands: Simple sweat glands that secrete sweat directly onto the SKIN.Neoplasms, Adnexal and Skin Appendage: Neoplasms composed of sebaceous or sweat gland tissue or tissue of other skin appendages. The concept does not refer to neoplasms located in the sebaceous or sweat glands or in the other skin appendages.Iris: The most anterior portion of the uveal layer, separating the anterior chamber from the posterior. It consists of two layers - the stroma and the pigmented epithelium. Color of the iris depends on the amount of melanin in the stroma on reflection from the pigmented epithelium.Syndrome: A characteristic symptom complex.Neoplasms, Multiple Primary: Two or more abnormal growths of tissue occurring simultaneously and presumed to be of separate origin. The neoplasms may be histologically the same or different, and may be found in the same or different sites.Blood-Aqueous Barrier: The selectively permeable barrier, in the EYE, formed by the nonpigmented layer of the EPITHELIUM of the CILIARY BODY, and the ENDOTHELIUM of the BLOOD VESSELS of the IRIS. TIGHT JUNCTIONS joining adjacent cells keep the barrier between cells continuous.Albinism, Ocular: Albinism affecting the eye in which pigment of the hair and skin is normal or only slightly diluted. The classic type is X-linked (Nettleship-Falls), but an autosomal recessive form also exists. Ocular abnormalities may include reduced pigmentation of the iris, nystagmus, photophobia, strabismus, and decreased visual acuity.Nevus, Spindle Cell: A form of pigmented nevus showing intense melanocytic activity around the dermo-epidermal junction. Large numbers of spindle-shaped melanocytes proliferate downward toward the dermis and usually a large amount of pigment is present. It was first described in 1976 and the bulk of patients reported have been young females with the lesions presenting on the thighs. (From Rook et al., Textbook of Dermatology, 4th ed, 1992, p185)Hypertrichosis: Excessive hair growth at inappropriate locations, such as on the extremities, the head, and the back. It is caused by genetic or acquired factors, and is an androgen-independent process. This concept does not include HIRSUTISM which is an androgen-dependent excess hair growth in WOMEN and CHILDREN.Laser Therapy: The use of photothermal effects of LASERS to coagulate, incise, vaporize, resect, dissect, or resurface tissue.Eye Neoplasms: Tumors or cancer of the EYE.Eye: The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.Vitiligo: A disorder consisting of areas of macular depigmentation, commonly on extensor aspects of extremities, on the face or neck, and in skin folds. Age of onset is often in young adulthood and the condition tends to progress gradually with lesions enlarging and extending until a quiescent state is reached.Sturge-Weber Syndrome: A non-inherited congenital condition with vascular and neurological abnormalities. It is characterized by facial vascular nevi (PORT-WINE STAIN), and capillary angiomatosis of intracranial membranes (MENINGES; CHOROID). Neurological features include EPILEPSY; cognitive deficits; GLAUCOMA; and visual defects.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Scleral Diseases: General disorders of the sclera or white of the eye. They may include anatomic, embryologic, degenerative, or pigmentation defects.Monophenol Monooxygenase: An enzyme of the oxidoreductase class that catalyzes the reaction between L-tyrosine, L-dopa, and oxygen to yield L-dopa, dopaquinone, and water. It is a copper protein that acts also on catechols, catalyzing some of the same reactions as CATECHOL OXIDASE. EC 1.14.18.1.Proteus Syndrome: Hamartoneoplastic malformation syndrome of uncertain etiology characterized by partial GIGANTISM of the hands and/or feet, asymmetry of the limbs, plantar hyperplasia, hemangiomas (HEMANGIOMA), lipomas (LIPOMA), lymphangiomas (LYMPHANGIOMA), epidermal NEVI; MACROCEPHALY; cranial HYPEROSTOSIS, and long-bone overgrowth. Joseph Merrick, the so-called "elephant man", apparently suffered from Proteus syndrome and not NEUROFIBROMATOSIS, a disorder with similar characteristics.Bowen's Disease: A persistent progressive non-elevated red scaly or crusted plaque which is due to an intradermal carcinoma and is potentially malignant. Atypical squamous cells proliferate through the whole thickness of the epidermis. The lesions may occur anywhere on the skin surface or on mucosal surfaces. The cause most frequently found is trivalent arsenic compounds. Freezing, cauterization or diathermy coagulation is often effective. (From Rook et al., Textbook of Dermatology, 4th ed, pp2428-9)Keratoacanthoma: A benign, non-neoplastic, usually self-limiting epithelial lesion closely resembling squamous cell carcinoma clinically and histopathologically. It occurs in solitary, multiple, and eruptive forms. The solitary and multiple forms occur on sunlight exposed areas and are identical histologically; they affect primarily white males. The eruptive form usually involves both sexes and appears as a generalized papular eruption.Melanoma-Specific Antigens: Cellular antigens that are specific for MELANOMA cells.Melanosomes: Melanin-containing organelles found in melanocytes and melanophores.Nevus, Blue: Usually a benign tumor, that commonly presents as a solitary blue nodule with spindled MELANOCYTES covered by smooth SKIN. Several variants have been identified, one variant being malignant. The blue color is caused by large, densely packed melanocytes deep in the DERMIS of the nevus. In CHILDREN, they usually occur on the BUTTOCKS and LUMBOSACRAL REGION and are referred to as cellular blue nevi. Malignant blue nevi are more commonly found on the SCALP.Coloboma: Congenital anomaly in which some of the structures of the eye are absent due to incomplete fusion of the fetal intraocular fissure during gestation.Port-Wine Stain: A vascular malformation of developmental origin characterized pathologically by ectasia of superficial dermal capillaries, and clinically by persistent macular erythema. In the past, port wine stains have frequently been termed capillary hemangiomas, which they are not; unfortunately this confusing practice persists: HEMANGIOMA, CAPILLARY is neoplastic, a port-wine stain is non-neoplastic. Port-wine stains vary in color from fairly pale pink to deep red or purple and in size from a few millimeters to many centimeters in diameter. The face is the most frequently affected site and they are most often unilateral. (From Rook et al., Textbook of Dermatology, 5th ed, p483)Microphthalmia-Associated Transcription Factor: A basic helix-loop-helix leucine zipper transcription factor that regulates the CELL DIFFERENTIATION and development of a variety of cell types including MELANOCYTES; OSTEOCLASTS; and RETINAL PIGMENT EPITHELIUM. Mutations in MITF protein have been associated with OSTEOPETROSIS and WAARDENBURG SYNDROME.Uveal Neoplasms: Tumors or cancer of the UVEA.ColoradoHair Diseases: Diseases affecting the orderly growth and persistence of hair.MART-1 Antigen: A melanosome-specific protein that plays a role in the expression, stability, trafficking, and processing of GP100 MELANOMA ANTIGEN, which is critical to the formation of Stage II MELANOSOMES. The protein is used as an antigen marker for MELANOMA cells.Cyclic AMP-Dependent Protein Kinase RIalpha Subunit: A type I cAMP-dependent protein kinase regulatory subunit that plays a role in confering CYCLIC AMP activation of protein kinase activity. It has a lower affinity for cAMP than the CYCLIC-AMP-DEPENDENT PROTEIN KINASE RIBETA SUBUNIT.Mongolian Spot: A bluish-gray to gray-brown benign, melanocytic nevus found usually in the LUMBOSACRAL REGION of dark-skinned people, especially those of East Asian ancestry. It is usually congenital or appears shortly after birth, and disappears in childhood.Choroid: The thin, highly vascular membrane covering most of the posterior of the eye between the RETINA and SCLERA.Leukokeratosis, Hereditary Mucosal: An autosomal dominant disorder that is manifested by thickened spongiform ORAL MUCOSA with a white opalescent tint. Other MUCOSAL TISSUE may also be involved mucosa found in the VAGINA; RECTUM, and NASAL CAVITY may be similarly involved. This form of LEUKOKERATOSIS can be caused by a mutation in the gene for KERATIN 4 and is not considered a PRENEOPLASTIC CONDITION.