Nevus refers to benign skin/mucous membrane malformations (pigment mark, often called “mole” or “birthmark” in common parlance). The following forms can be distinguished:
Dermal melanocytic nevi (ICD-10 D22.9).
- Mongolian spot – indistinct gray-blue discoloration of the skin in the buttock/back area; regresses by puberty; usually seen in Mongolians.
- Nevus coeruleus (blue nevus) – coarse blue-black nodules that appear mainly on the back of the hand or arm.
- Naevus fusco-coeruleus – blurred flat blue-black pigmentation in the area of the face (naevus Ota; synonym: oculodermal melanocytosis)/shoulder (naevus Ito); possibly with hypertrichosis (increased body and facial hair; without a male distribution pattern); occurs in Mongolians and Japanese.
Epidermal melanocytic nevi – refers to marks characterized by a sharply demarcated brown patch (ICD-10 D22.9)
- Café-au-lait spot (nevus pigmentosus).
- Ephelides (freckles)
- Lentigines (lentigo simplex)
- Melanosis naeviformis (Becker’s nevus) – extensive brown colored skin area, which occurs in combination with hypertrichosis increased body and facial hair; without a male distribution pattern).
- Nevus spilus – combination of café-au-lait spots and small-spotted pigment cell nests.
Nevus cell nevus (NZN) – Marks that go through the following stages:
- Junctional nevus – sharply demarcated spot/dot-shaped marks that are homogeneously brown(-black) in color.
- Compound nevus – sharply demarcated, usually nodular brown(-black) marks, often with a fissured surface; hypertrichosis may accompany; usually form from junctional nevi
- Dermal nevi – papular brown marks with hair trimming.
Special forms of nevus cell nevi
- Benign juvenile melanoma (spindle cell nevus; Spitz tumor) – circumscribed benign nodular marks occurring in children/adolescents.
- Dysplastic nevus (atypical nevus, active nevus) – acquired nevus cell nevus with outgrowths, irregular pigmentation/color changes, increase in size, signs of inflammation.
- Halo nevus (Sutton nevus) – harmless marks characterized by a white halo.
- Nevus pigmentosus et pilosus (giant pigmented nevus) – often appearing as bathing trunks nevus in the context of neurocutaneous melanosis.
Vascular nevi, hemangiomas (blood sponges or strawberry spot).
- Nevus flammeus (ICD-10 Q82.5; port-wine stain; nevus teleangiectaticus; planar hemangioma) – sharply circumscribed light to blue-red spots.
- Medial nevus flammeus – common on neck, forehead; often regress; newborns sometimes have a pale port-wine stain on neck, popularly known as “stork bite”; this occurs in virtually every baby
- Lateral nevus flammeus – often localized on the face; rarely regress; may occur as part of complex malformations
- Nevus araneus (synonyms: Nevus stellatus; spider nevus, star nevus, or vascular spider or Eppinger’s star, spider nevus, spider nevi) – change occurring in children or in advanced liver disease, in which a central papule is surrounded by star-shaped venules.
- Teleangictasia hereditaria haemorrhagica (Osler-Rendu disease) – dilatation of end-stromal vessels caused by an autosomal dominant hereditary disease.
- Hemangioma (ICD-10 D18.0) – pale to blackish-blue vascular growths that occur in early childhood or are congenital
- Granuloma pyogenicum (ICD-10 L98.0; granuloma teleangiectaticum, botryomycoma) – benign spherical soft neoplasms that occur after an infected injury
Epidermal nevi
- Common, usually congenital, usually striated thickening of the epidermis (cuticle).
Sebaceous nevi (nevus sebaceus).
- Sharply circumscribed often spherical marks arranged in a cobblestone to papillomatous pattern; occurs more frequently in childhood/adolescence
Other nevi
- Apocrine/ecrine sweat gland nevi
- Connective tissue nevi
- Elastica nevi
- Hair nevi
- Comedone nevi
- Nevus lipomatosus superficialis – it is a circumscribed fat tissue nevus with development of fat tissue lobules throughout the dermis (skin).
The most common nevi are nevus cell nevus (may be present at birth or develop during life, see below ) and lentigo simplex (may be present at birth or, more commonly, develop in early childhood). The risk of melanoma increases almost linearly with the number of melanocytic nevi (MN). Peak incidence: the majority of melanocytic nevi (MN) develop in the first 20-30 years of life. The maximum incidence of sebaceous nevus is in childhood and puberty.Epidermal nevi occur predominantly in childhood. The prevalence (disease frequency) for dysplastic nevi is 5% of white-skinned adults (in Germany). A white-skinned adult has on average about 20 acquired nevus cell nevi.The prevalence for epidermal nevi is 0.1% of all children.Congenital nevi (KMN; resp. melanocytic nevi) are found in about 1% of newborns.Hemangiomas are found in 8-12% of all babies, especially in girls and premature infants. Progression and prognosis: An assignment of a person’s pigmented nevi and the associated assessment of melanoma risk (risk of skin cancer) should be made by a dermatologist. The risk of developing melanoma correlates with the total number of neus cell nevi. Ephelides (freckles), café au lait spots (from French. Café au lait = “milk coffee“; light brown, uniform skin spots of varying size) and the small-spotted lentigenes (lentigo simplex, lentigo solaris; age spots) do not pose a risk for the development of melanoma.Sebaceous nevi are usually congenital and may regress spontaneously (by themselves) in adulthood. In 10-30% of cases, a sebaceous nevi may develop into a basal cell carcinoma or other malignant (malignant) tumor.
