Skin melanocytic tumor

Melanocytic tumors on acral skin and nail apparatus

Acral melanoma

Topic Completed: 1 May 2013

Minor changes: 3 November 2020

Copyright: 2002-2022,, Inc.

PubMed Search: Acral melanoma (ALM)

Christopher S. Hale, M.D.
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Cite this page: Hale CS. Acral melanoma. website. Accessed January 18th, 2022.
Definition / general
  • Acral: relating to or affecting the glabrous (nonhair bearing) or volar skin of the soles, palms and digits as well as the nail apparatus
  • Note: all melanomas of acral sites do NOT have histology of acral lentiginous melanoma (Br J Dermatol 2012;166:727)
  • Rare; age adjusted incidence of 1.8 per million person years (Arch Dermatol 2009;145:427)
  • More common in blacks and Asians; ~10% of melanomas in whites
  • Older age than other variants (66 vs. 52 years), associated with other malignancies; less often associated with sunburn
  • Usually palms and soles, subungual, mucocutaneous oral and nasal cavity or anus
Clinical features
Prognostic factors
Case reports
Clinical images

Images hosted on other servers:

Plantar surface

Erosive and macerated lesion

In situ 5 years ago (fig. A)

Invasive ALM (fig. A and B)

  • May have parallel ridge pattern (band-like pigmentation on ridges of skin markings is specific)
Microscopic (histologic) description
  • Confluent single cell melanocytic proliferation
  • Variable cytologic atpyia of melanocytes
  • Prominent acanthosis of epidermis with elongated rete ridges
  • Pagetoid spread
  • Proliferation of melanocytes downward along eccrine ducts
  • Melanocytes may display prominent dendritic proceses
  • Invasive component often composed of spindle cells but epithelioid, small cells and pleomorphic cells are occasionally noted
  • Intraepidermal lentiginous component is similar to lentigo maligna but intraepidermal melanocytes are bizarre, epidermis is markedly hyperplastic and papillary dermis is widened and inflamed
  • Consumption of epidermis present (attenuation of basal / suprabasal layers with rete ridge loss, J Cutan Pathol 2012;39:577)
  • Early lesions may show proliferation of solitary melanocytes in crista profunda intermedia, the epidermal rete ridge underlying the ridge of the skin marking (Am J Dermatopathol 2006;28:21)
  • Nail lesions show confluent stretches of solitary melanocytes, multinucleation, lichenoid inflammatory reaction and florid pagetoid spread (Am J Surg Pathol 2008;32:835)
Microscopic (histologic) images

Contributed by Angel Fernandez-Flores, M.D., Ph.D.

Acral lentiginous melanoma

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In situ (fig. B)

Invasion: nest formation by melanoma cells (fig. C and D)

Molecular / cytogenetics description
Differential diagnosis
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