NEVI A generally accepted definition has not been achieved. The most common abnormalities in development of the skin, and apparently serve no function. The excess (or deficiency) of tissue or cells, which may involve epidermal, connective tissue, adnexal, nervous, or vascular elements. Lesions with a circumscribed alteration in the arrangement or quantitative composition of otherwise normal cutaneous elements.

NEVI  Nevi (moles) presenting at birth are referred to as congenital nevi (hereditary or non-hereditary).  Some nevi may develop later in life (acquired nevi).  Nevi don´t grow other than to keep pace with the patients growth ( X except melanocytic nevi).  Nevi usually don´t show malignant tranformation ( X with exception of large melanocytic nevi).

NEVI  Diagnosis: clinical features, dermatoskopy, histological examination  Therapy: ▪ nevi are usually permanent, in some cases can partially regress during childhood (nevus flammeus) or even disappear (melanocytic nevi) ▪ surgical treatment, elektrosurgery, laserotherapy

Tissue and Organoid Nevi  Epidermal Nevus  Melanocytic Nevus  Nevus Elasticus  Nevus Lipomatosus Superficialis  Nevus Flammeus (Port-Wine Stain, stork-bite nevus, nevus teleangiectaticus)  Nevus Anemicus  Nevus Sebaceus  Nevus Comedonicus  Ecrinne Nevus  Hair Follicle Nevus ٭ underlined = the most frequent

Epidermal (verrucosus, hyperkeratoticus) N.  E.nevi are formed by excessive proliferation of the epidermal cells (the component may be sebaceous, apocrine, eccrine, follicular, or keratinocytic).  Most of the lesions are present at birth = congenital (embryonal ectodermal origin), but some lesions may appear later in life also..

Epidermal (verrucosus, hyperkeratoticus) N.  They occur in form of hyperkeratotic, verrucose plaques or nodules which appear in a localized area or may be arranged either in a linear fashion, zosteriform, or in irregular bizarre shapes, and may cover most of the body (billateraly).  E.n. are usually asymptomatic, with the exception of „inflammatory linear verrucous epidermal nevus“ →

Inflammatory Linear Verrucous Epidermal Nevus = Epidermal Nevus Syndrome  ILVEN is a linear, persistent, pruritic plaque, usually first noted on a limb (or face, the trunk) in early childhood (or later - to age 40 years).  It is uncommon, has a female predominance, with a female-to-male ratio of 4:1.  An estimated one third of individuals have involvement of other organ systems (congenital ectodermal defects in the skin, brain, eyes, and/or skeleton) = ENSyndrome.

Naevus Elasticus (N.Collagenicus)  „Collagenomas“ and „elastomas“ generally present during the postpubertal period.  Multiple, indurated papulonodules that vary in size, in a zosteriform pattern or solitary, are localized in the lumbosacral area or over the upper two thirds of the back.  Shagreen patch (shark´s skin) is a collagenoma variant associated with tuberous sclerosis (a disease inherited in an autosomal dominant pattern).

Nevus (cutaneous) Lipomatosus Superficialis  N.l. is an uncommon benign hamartomatous condition characterized by the presence of mature ectopic adiopocytes in the dermis.  Usually multiple, soft, yellowish or skin-colored papules, nodules, or plaques, mostly involving the pelvic or gluteal region.  Sometimes it presents as a solitary dome-shaped sessile papule.

 Naevus Flammeus Medialis Nuchae ( colloquially stork-bite nevus) - is very common type of nevus flammeus is present at birth in the location where the „stork“ would carry the baby.  Haemangioma capillare, cavernosum  Nevus Flammeus (Port-Wine Stain, nevus teleangiectatius) - a benign proliferation of blood vessels in the dermis. - its clinical appearance depends on the number, size, and depth of the proliferative vessels. - usually it´s located on the face & persists to adulthood.

 Naevus Anaemicus  Very rare cutaneous condition, it is the example of a „pharmacologic“ nevus (X no reduced number of blood vessels).  The vessels in a given area are sensitive to catecholamines and remain constricted.

Nevus Sebaceus ( of Jadassohn)  Congenital (presenting at birth) variant: hairless yelowish plaque that typically occurs on the face or scalp, affecting males and females of all races equally. Larger s.n. can give rise to sebaceous carcinoma.  N.s. occuring during adult life (very common variant) is benign overgrowth of sebaceous glands in the area.

Eccrine and Apocrine Nevi  Extremely rare benign lesions.  An eccrine nevus is characterized by an increase in number and size of normal eccrine secretory coils.  An apocrine nevus is composed of hyperplastic mature apocrine glands. Usually is situated on upper chest and in axilla.  Histologically consists of numerous apocrine glands extending from the reticular layer of the dermis to the subcutaneous tissue.

Nevus comedonicus (n.follicularis keratosus, n.acneiformis unilateralis, n.zoniformis )  Histopathological exam reveal multiple atrophic cystically dilated hair follicles containing abundant keratinous debris and small projections of epithelial cells extending from the wall of the cyst into the surrounding dermis.  Very rare congenital „hamartoma“ of the pilosebaceous unit.  It looks like confluent clusters of open comedones (plugged pores) and scars, sometimes in a linear (or zonal) distribution.

Melanocytic (pigmented) Nevi  Pigmented melanocytic nevi (from nevus cells) are considered a normal skin finding.  They are congenital or acquired.  Most nevi are acquired after 6 months of age and before age 40.  Sun exposure as well as family tendency (heredity) play a role in the development of moles.

Melanocytic (pigmented) Nevi Congenital  They are present at birth (or in the first two years of life).  One in every people is born with a small mole.  Therapy: the profylactic removal is not usually required, only when nevus has changed in color or shape.

Melanocytic (pigmented) Nevi Congenital  „Giant“ nevi can cover a very large part of the body, so-called the „bathing-suit“ or „garment-like“ nevi (are found in every race, and strike genders equally).  They are rare but have a significant potential for developing of malignant melanoma! (6% to 12%)  Therapy: multiple excisional surgical procedures with the use of serial skin expanders.

Melanocytic (pigmented) Nevi Congenital Becker's nevus (also known as "Becker's melanosis,“ Nevoid melanosis," and "Pigmented hairy epidermal nevus”) is a skin disorder predominantly affecting males. The nevus first appears as an irregular hyperpigmentation usually on the trunk or upper arm and gradually enlarges irregularly, becoming thickened and often hairy.

Common Melanocytic (pigmented) Nevi („commonly acquired during life“)  Darkening in color, itching, growth, or development of new nevi during adolescence or pregnancy is common.  Nevi (moles) may sometimes become inflamed or irritated by friction from rubbing (by contact with rough clothing) or other types of injury.  After they stop growing (stabilize), they may persist or they may become smaller (regress) later in life.

 These nevi develop later in life, often during puberty or young adulthood. The typical adult has on the average 20 melanoc. nevi.  Nevi may grow or also regress in later adult life.  They are described as: - junctional (nests of nevus cells between epidermis and dermis) - compound (nests of nevus cells at the epidermal-dermal junction AND in the dermis) - dermal (nests of nevus cells in the dermis) Dg.: clinical findings, dermatoskopy, histology Melanocytic Nevi - commonly acquired

JUNCTIONAL nevus: a flat dark brown spot, usually several mm in diameter, with regular well-fined border and smooth surface Diff.dg.: lentigo simplex (incresed numbers of melanocytes), dysplastic nevus, melanoma in situ

Melanocytic Nevi - commonly acquired COMPOUND nevus: a slightly elevated lesion, brown - sometimes with irregular pigmented network (brown and flesh-colored), with smooth or uneven surface

Melanocytic Nevi - commonly acquired (INTRA)DERMAL nevus: an elevated, verrucous, sessile lesion, brown or flesh-colored, smooth or rough surface, sometimes with hair

Melanocytic Dysplastic Nevi (atypical moles)  Dysplastic nevus: an irregular shape and color, sharply bordered, 5mm in size (less or more)…but more often small dark brown or black flat spot, a few mm in diameter & specific histological features  Dysplastic nevi can be MM precursors and markers for MM susceptibility!  Therapy: excision, follow-up of individuals with DN at 6 to 12-month intervals (with measurement of lesions or dermatoskopic examinaton)

Halo nevus (Sutton nevus)  Halo nevi are common benign skin lesions that represent melanocytic nevi in which an inflammatory infiltrate develops, resulting in a zone of depigmentation surrounding the nevus.  They are entirely benign lesions and of only cosmetic significance.

Blue Nevus  These benign lesions are elevated, smooth-surfaced papules or plaques that are gray-blue to bluish black in color. Lesions are usually solitary, on the buttocks, the sacral region, and occasionally on the dorsal aspects of the hands and the feet.  Blue nevi propably represent dermal arrest in embryonal migration of neural crest melanocytes that fail to reach the epidermis.

Spitz Nevus (benign juvenile melanoma, spindle cell nevus)  Benign melanocytic tumor, primarily seen in children.  The typical Spitz nevus is a red-brown, dome- shaped nodule seen most often on the face of a child. Usually less than 1 cm in diameter and may have appeared over weeks to months.  A Spitz nevus can arise de novo or in association with an existing melanocytic nevus.  Melanocytes from a Spitz nevus may seed the regional lymph nodes, but this is not metastases.

Reed´s Nevus  A small, black, well-circumscribed, barely elevated papule.  It imitates malignant melanoma  Dg.: dermatoskopy (so called „starburst“), histology