- : A pigmented spot on the skin, such as a mole. The plural of nevus is nevi.
* * *1. A circumscribed malformation of the skin, especially if colored by hyperpigmentation or increased vascularity; a n. may be predominantly epidermal, adnexal, melanocytic, vascular, or mesodermal, or a compound overgrowth of these tissues. 2. A benign localized overgrowth of melanin-forming cells of the skin present at birth or appearing early in life. SYN: mole (1). [L. naevus, mole, birthmark]- acquired n. a melanocytic n. that is not visible at birth, but appears in childhood or adult life.- n. anemicus a functional developmental defect in vascular filling characterized by pale, round or oval, flat lesions, indistinguishable from surrounding normal skin on diascopy.- n. araneus SYN: spider angioma.- basal cell n. [MIM*109400] a hereditary disease noted in infancy or adolescence, characterized by lesions of the eyelids, nose, cheeks, neck, and axillae, appearing as uneroded flesh-colored papules, some becoming pedunculated, and histologically indistinguishable from basal cell epithelioma; also noted are punctate keratotic lesions of the palms and soles; the lesions usually remain benign, but in some cases ulceration and invasion occur and are evidence of malignant change; autosomal dominant inheritance; caused by mutation in the human PTCH, the homolog of the “patched gene” of Drosophila. PTCH is found on chromosome 9q22.- bathing trunk n. a large hairy congenital pigmented n. with a predilection for the entire lower trunk; malignant melanoma may develop in childhood. SYN: giant pigmented n..- Becker n. a n. first seen as an irregular pigmentation of the shoulders, upper chest, or scapular area, gradually enlarging irregularly and becoming thickened and hairy. SYN: pigmented hair epidermal n..- blue n. a dark blue or blue-black n. covered by smooth skin and formed by heavily pigmented spindle-shaped or dendritic melanocytes in the reticular dermis.- blue rubber-bleb nevi a syndrome characterized by erectile, easily compressible, thin-walled hemangiomatous nodules, present at birth, widely distributed in the skin and the alimentary canal and sometimes in other tissues; lesions in the gut may perforate or cause hemorrhage, and the patient may be anemic from continual bleeding.- n. cavernosus SYN: cavernous angioma.- cellular blue n. a large, acquired blue n. in which melanocytes are often clear and large, alternating with pigmented spindle cells and which may expand deeply into the subcutis; malignant change is very rare.- n. comedonicus congenital or childhood linear keratinous cystic invaginations of the epidermis, with failure of development of normal pilosebaceous follicles.- compound n. a n. in which there are nests of melanocytes in the epidermal-dermal junction and in the dermis.- congenital n. a melanocytic n. that is visible at birth, is often larger than an acquired n., and more frequently involves deeper structures. Congenital n. larger than 20.0 cm in diameter, termed giant congenital nevi, have a 6–12% lifetime risk of developing melanoma. SEE ALSO: bathing trunk n..- dysplastic n. a n. exceeding 5 mm in diameter, with irregular, indistinct, or notched borders and mixed tan-to-black and pink-to-red color. Microscopically these are basally nested and scattered intraepidermal melanocytes with hyperchromatic nuclei larger than those of basal keratinocytes. If multiple and associated with a family history of melanoma, these nevi have a high risk of malignant change, but isolated dysplastic nevi in the absence of a family history of melanoma are less frequently premalignant. SEE ALSO: malignant mole syndrome. See dysplastic n. syndrome.- faun tail n. a circumscribed growth of hair of the lumbosacral area, associated with diastematomyelia.- n. flammeus, flame n. a large congenital vascular malformation n. having a purplish color; it is usually found on the head and neck and persists throughout life. SEE ALSO: Sturge-Weber syndrome. SYN: port-wine stain.- halo n. a benign, sometimes multiple, melanocytic n. in which involution occurs with a central brown mole surrounded by a uniformly depigmented zone or halo. SYN: leukoderma acquisitum centrifugum, Sutton n..- inflammatory linear verrucous epidermal n. rare pruritic confluent scaly erythematous papules in linear array, usually appearing in early childhood on a limb and resolving before adulthood.- intradermal n. a n. 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.- Ito n. pigmentation of skin innervated by lateral branches of the supraclavicular nerve and the lateral cutaneous nerve of the arm, due to scattered, heavily pigmented, dendritic melanocytes in the dermis.- junction n. a n. consisting of nests of melanocytes in the basal cell zone, at the junction of the epidermis and dermis, appearing as a slightly raised, small, flat, nonhairy pigmented (brown or black) tumor.- Ota n. SYN: oculodermal melanosis.- n. papillomatosus a prominent wartlike mole.- n. pigmentosus a benign pigmented melanocytic proliferation; raised or level with the skin, present at birth or arising early in life. SYN: mole (2).- n. sebaceus congenital papillary acanthosis of the epidermis, with hyperplasia of sebaceous glands developing at puberty and presence of apocrine glands in nonapocrine areas of the skin (commonly the scalp). A variety of epithelial tumors may arise from a n. sebaceus in adult life, most commonly basal cell carcinoma. SYN: Jadassohn n..- Spitz n. a benign, slightly pigmented or red superficial small skin tumor composed of spindle-shaped, epithelioid, and multinucleated cells that may appear atypical; most common in children, but also appearing in adults. SYN: benign juvenile melanoma, epithelioid cell n., spindle cell n..- strawberry n. a small n. vascularis (capillary hemangioma) resembling a strawberry in size, shape, and color; it usually disappears spontaneously in early childhood. See capillary hemangioma. SYN: strawberry birthmark.- n. unius lateris a congenital systematized linear n. limited to one side of the body or to portions of the extremities on one side; lesions are often extensive, forming wave-like bands on the trunk and spiraling streaks on the extremities. SYN: linear epidermal n..- Unna n. capillary stain on nape of neck; persistent form of n. flammeus nuchae. SYN: erythema nuchae.- n. vascularis, n. vasculosus SYN: capillary hemangioma.- n. venosus a n. formed of a patch of dilated venules.- verrucous n. a skin-colored or darker wartlike, often linear lesion appearing at birth or early in childhood and occurring in various sizes and locations, single or multiple.- white sponge n. [MIM*193900] an autosomal dominant condition of the oral cavity characterized by soft, white or opalescent, thickened, and corrugated folds of mucous membrane; other mucosal sites are occasionally involved simultaneously; caused by mutation in either the mucosal keratin gene K4 on chromosome 12 or keratin-13 gene on 17. SYN: familial white folded dysplasia, oral epithelial n..- woolly hair n. [MIM*194300] a circumscribed patch of fine, curly hair in an otherwise normal scalp appearing during childhood and enlarging for a period of 2–3 years; autosomal dominant inheritance. There is another, mostly sporadic form that may be autosomal recessive [MIM*278150].
* * *ne·vus or chiefly Brit nae·vus 'nē-vəs n, pl ne·vi or chiefly Brit nae·vi -.vī a congenital or acquired usu. highly pigmented area on the skin that is either flat or raised: MOLE see BLUE NEVUS, junctional nevus, spider nevus
* * *ne·vus (neґvəs) pl. neґvi [L. naevus] 1. any congenital lesion of the skin; see also birthmark. 2. a type of hamartoma representing a circumscribed stable malformation of the skin or occasionally the oral mucosa, which is not due to external causes and therefore presumed to be of hereditary origin. The excess (or deficiency) of tissue may involve epidermal, connective tissue, adnexal, nervous, or vascular elements.
Medical dictionary. 2011.