Skin melanocytic tumor
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Giant congenital nevus


Topic Completed: 1 November 2012

Minor changes: 3 November 2020

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PubMed Search: Giant congenital nevus

Christopher S. Hale, M.D.
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Cite this page: Hale CS. Giant congenital nevus. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumormelanocyticgiantcongenitalnevus.html. Accessed March 5th, 2021.
Definition / general
Terminology
  • Also called giant pigmented nevus or giant hairy nevus
Epidemiology
  • 1 in 500,000 live births (Br J Dermatol 1981;104:307)
  • ~2.5% risk of malignant transformation, usually before adolescence (Br J Dermatol 2006;155:1); may give rise to cutaneous or CNS melanoma or related neuroectodermal tumors (malignant peripheral nerve sheath tumor, cutaneous malignant melanotic neurocristic tumor, rhabdomyosarcoma, liposarcoma)
  • May contain pseudotumoral proliferative nodules that ulcerate (J Cutan Pathol 2010;37:764)
  • May have satellite nevi, including within mucosal membranes
  • Truncal nevi may develop symptomatic neurocutaneous melanosis (meningeal or cerebral melanosis), lethal in 1/3 (J Am Acad Dermatol 2006;54:767)
Sites
  • Dermatomal, "bathing suit" or "garment" configuration; may involve entire scalp, extremity, most of trunk or placenta
  • Scalp lesions are often in thickened folds of skin resembling cerebrum, may involute in first 2 years of life (J Am Acad Dermatol 2008;58:508)
Case reports
Treatment
Clinical images

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Newborn with giant hairy congenital nevus

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Ulcerated nodule within scalp

Microscopic (histologic) description
  • Similar to congenital nevus
  • Deeper nevus cells may be E-cadherin negative, contributing to their motility (J Dermatol Sci 2008;52:21)
Microscopic (histologic) images

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Proliferation of melanocytes along hair follicle

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Melanocytes are uniform in large ulcerated nodule

Molecular / cytogenetics description
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