Skin - Melanocytic tumor
Melanoma
Acral lentiginous melanoma (ALM)

Author: Christopher Hale, M.D. (see Authors page)

Revised: 21 February 2017, last major update May 2013

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Acral lentiginous melanoma (ALM)

Cite this page: Acral lentiginous melanoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skintumormelanocyticacrallentiginous.html. Accessed May 24th, 2017.
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)
Epidemiology
  • 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
Sites
  • 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)

Dermoscopy
  • 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

Images hosted on other servers:

In situ (fig. B)

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

Various images

Molecular / cytogenetics description
Differential diagnosis