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Agminated nevus - Skin
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Agminated nevus - Skin

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Contributors: Chris G. Adigun MD, Jeffrey D. Bernhard MD, Sarah Stein MD, Karen Wiss MD, Sheila Galbraith MD, Craig N. Burkhart MD, Dean Morrell MD, Lynn Garfunkel MD, Nancy Esterly MD
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Synopsis

An agminated nevus consists of a cluster of nevi confined to a localized area of the body. The term agminated is derived from the Latin word agmen, meaning aggregation. Typically, an agminated nevus presents as a group of multiple nevi in a circumscribed area of skin, usually smaller than 10 cm in diameter. The intervening skin between lesions is not discolored or hyperpigmented but may show a speckled pigmentation.

Agminated nevi may consist of benign melanocytic nevi, atypical or dysplastic nevi, blue nevi, or Spitz nevi. Agminated nevi may be acquired or congenital. Agminated common melanocytic and dysplastic nevi are invariably acquired. If the lesion is acquired, it typically develops during puberty and may continue to evolve in early adolescence.

The main lesion that must be differentiated from an agminated nevus is the nevus spilus. A nevus spilus consists of a tan lentiginous background patch upon which are distributed numerous deeply pigmented macules and papules. Histologically, the pigmented background resembles a simple lentigo, and the darker lesions appear as junctional or compound nevi.

Agminated nevi are thought to arise as a result of loss of heterozygosity (LOH) occurring in a somatic cell during embryogenesis. This results in an area of skin populated by cells that are homozygous or hemizygous for the major gene responsible for the development of melanocytic nevi.

Agminated common and dysplastic nevi appear to be associated with the presence of multiple disseminated clinically atypical melanocytic nevi (the dysplastic nevus syndrome phenotype [DNS]).

There is some evidence to suggest that a genetic association exists between agminated nevi and DNS phenotypes. In this context, agminated nevi are thought to arise as a consequence of postzygotic LOH, thus representing a type 2 segmental manifestation of the atypical mole syndrome phenotype. However, microdissection techniques to analyze an LOH pattern have not confirmed this theory.

Although the risk for malignant change of agminated melanocytic nevi has not yet been defined, melanoma arising from agminated melanocytic nevi has been described. These patients should thus be considered at higher risk for subsequent melanoma development.

Codes

ICD10CM:
Q82.5 – Congenital non-neoplastic nevus

SNOMEDCT:
402555001 – Multiple benign melanocytic nevi

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Last Updated: 10/15/2013
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Agminated nevus - Skin
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Agminated nevus : Brown color, Grouped configuration, Hyperpigmented patch, Irregular configuration, Hyperpigmented macules
Clinical image of Agminated nevus
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