Skin - Melanocytic tumor
Melanoma
Lentigo maligna melanoma

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: Lentigo maligna melanoma

Cite this page: Lentigo maligna melanoma. PathologyOutlines.com website. http://pathologyoutlines.com/topic/skintumormelanocyticlentigomaligna.html. Accessed August 21st, 2017.
Definition / general
  • Atypical melanocytes in basal layer, individually and in nests (theques), associated with sun damage (eMedicine)
Terminology
  • Also called melanoma arising in Hutchinson freckle, actinic melanosis, melanoma on sun damaged skin and solar melanoma
  • Note: lentigo maligna (a subtype of melanoma in situ), by definition, does NOT infiltrate into dermis but lentigo maligna melanoma has at least single cell infiltration into papillary dermis
Clinical features
  • Flat, tan to black with irregular hyperpigmentation, > 2 cm
  • 5 - 15% of (invasive) melanoma; increasing prevalence, particularly among men age 65+ years (J Invest Dermatol 2005;125:685)
  • Slow growing lesion of sun exposed skin of elderly whites, often cheek; partial regression is common
  • Similar behavior to other melanoma subtypes when depth of invasion is considered but unusual to die of disease
  • Possible origin from progenitor stem cell (strongly CD133+ and CD34+) in outer root sheath of mid lower hair follicles (Dermatol Ther 2008;21:S1)
Case reports
Treatment
Dermoscopy
  • Annular granular pattern (Br J Dermatol 2012;167:280), asymmetric pigmented follicular openings, dark rhomboidal structures and homogeneous areas
Dermoscopy Images

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Annular granular pattern

With slate gray dots

Typical dermoscopy features

Clinical images

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Various Images

Microscopic (histologic) description
  • Contiguous growth of atypical melanocytes in basal layer, individually and in nests (theques)
  • Cells may be spindled, pleomorphic and have cytoplasmic retraction
  • Dermis shows solar elastosis
  • Also epidermal atrophy, actinic damage and basilar keratinocyte hyperpigmentation
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Angel Fernandez-Flores, M.D., Ph.D., Hospital El Bierzo and Clinica Ponferrada, Spain:

Various images



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Atypical melanocytes

Molecular / cytogenetics description
  • p.R163Q variant of MC1R gene is associated with lentigo maligna melanoma in Mediterranean populations (Br J Dermatol 2013;169:804)
Differential diagnosis