Nevus melanocytic (overview) D22.-

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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Synonym(s)

Birthmark; common melanocytic nevus; melanocytic nevus; Melanocytic nevus; more junctional nevus; Naevocyte nevus; Nevuscellnaevus; Nevus melanocytic; nevus naevocellularis; nevus pigmentosus; nevus pigmentosus naevocellularis; Pigmentation spot; Pigment mark; Pigment tumour

Definition
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Benign, congenital or acquired melanocytic, brown to brown-black, more rarely reddish or skin-coloured, spotty, nodular, plaque or nodular melanocytic tumours, which mostly occur in plural, but also solitary form. Melanocytic nevi may be restricted to the epidermis (lentigo simplex, junctional melanocytic nevus), located in the epidermis and dermis (compound type of melanocytic nevus) or exclusively in the dermis (dermal melanocytic nevus). This clinical/histological typing describes a sequential developmental process that all melanocytic nevi go through in stages.

Classification
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Classification of congenital and acquired melanocytic nevi according to histological and clinical criteria:

Etiopathogenesis
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It has been postulated that melanocytic nevi are derived from cells that migrate from the neural crest into the epidermis. Probably, melanocytes and "nevus cells" represent identical cell populations, so that the term "nevus cell" in connection with melanocytic nevi (alias nevus cell nevus) can be dispensed with.

Localization
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On the whole integument, also on superficial mucous membranes possible.

Histology
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Histologically 3 forms can be distinguished:
  • Junction type (initial epidermal stage)
  • Compound type (epidermo-dermal)
  • Dermal type: Dermal melanocytic nevus.
Melanocytic nevi show intraepidermal and/or dermal accumulations of melanocytes. The melanocytes within the junctional zone have a round, oval or spindly appearance and lie in contiguous nests. In the superficial dermis, the cells generally have an epithelioid cell character with medium-sized, usually centrally located nuclei and a distinct cytoplasmic border. The degree of pigmentation varies, either finely granular or cloggy distributed over the cytoplasm. The nuclei show a uniform distribution of chromatin with a slightly clumped texture. Deeper in the dermis the melanocytes are arranged in strands. Often the cells show a reduced cytoplasm content. They resemble lymphocytes and are often arranged in linear strands but also diffusely. The skin appendages are covered by the dermal melanocytes, but always remain intact.

Literature
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  1. Sheaf C (1992) Sun and malignant melanoma. dermatologist 43: 251-257
  2. Hesse G et al (1994) Microfilm documentation in the follow-up of melanocytic tumors. dermatologist 45: 532-535
  3. Maitra A et al (2002) Loss of heterozygosity analysis of cutaneous melanoma and benign melanocytic nevi: laser capture microdissection demonstrates clonal genetic changes in acquired nevocellular nevi. Hum Pathol 33: 191-197
  4. Ruiter DJ et al (2003) Current diagnostic problems in melanoma pathology. Seminar Cutan Med Surg 22: 33-41
  5. Schulz H (1992) Reflected light microscopic score for the differential diagnosis of dysplastic nevi. dermatologist 43: 487-490
  6. Schulz H (1994) Reflected light microscopic criteria of benign melanocytic pigment moles of the skin. Nude Dermatol 20: 2-6
  7. Synnerstad I et al (2004) Fewer melanozcytic nevi found in children with active atopic dermatitis than in children without dermatitis. Arch Dermatol 140:1471-1475
  8. Tomita K et al (1998) A nevocellular nevus consisting mostly of nevic corpuscles. J Dermatol 25: 134-135

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Please ask your physician for a reliable diagnosis. This website is only meant as a reference.

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Last updated on: 29.10.2020