Skin melanocytic tumor
Nevi
Acral


Topic Completed: 1 January 2017

Minor changes: 15 December 2019

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PubMed Search: skin melanocytic tumor acral

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Richard E. Horowitz, M.D.
Page views in 2019: 4,246
Page views in 2020 to date: 2,240
Cite this page: Horowitz R. Acral. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumormelanocyticnevisitesacral.html. Accessed August 7th, 2020.
Definition / general
  • Usually defined as nevi of palmar or plantar skin including nailbed
  • Some expand to include nevi of dorsal hands / feet or external ear (Mod Pathol 2006;19 Suppl 2:S4)
Epidemiology
  • Present in 4 - 9% of population, usually elderly patients
  • May resemble early acral melanoma, although melanomas are rare at these sites
  • Most common location in Asian patients
Clinical features
  • Circumscribed, light brown, not palpable and flat to side lighting
Dermoscopic description
  • Parallel patterns present (Dermatology 2008;216:205); more prominent pigmentation seen in sulci (furrows) of dermatoglyphs, indicative of benign nature
Clinical images

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Various patterns

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Transition pattern

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Various images

Microscopic (histologic) description
  • Histologic overlap exists with melanoma
  • May be junctional, compound or dermal
  • Lentiginous pattern more common than in nevi of non-acral sites
  • Often (61%) low level pagetoid, single cell migration into stratum spinosum (Am J Surg Pathol 1995;19:792), summarized by “MANIAC” (Melanocytic Acral Nevus with Intraepithelial Ascent of Cells)
  • Pagetoid cells should not be atypical and should not be present beyond center of lesion
  • Possible transepidermal elimination of pigment within stratum corneum
  • Nevus cells mature to lesional base
  • May have architectural disorder (J Cutan Pathol 2008;35:889)
Microscopic (histologic) images

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Contributed by Angel Fernandez-Flores, MD, PhD, Hospital El Bierzo and Clinica Ponferrada, Spain



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Retraction artifact,
cytological atypia and
pagetoid spread
Differential diagnosis
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