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Table of Contents
Definition / general | Terminology | Clinical features | Case reports | Treatment | Dermoscopy | Dermoscopy Images | Clinical images | Microscopic (histologic) description | Microscopic (histologic) images | Molecular / cytogenetics description | Differential diagnosisCite this page: Lentigo maligna melanoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skintumormelanocyticlentigomaligna.html. Accessed June 25th, 2018.
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
- 51 year old woman with Fitzpatrick skin type III (Dermatology 2008;217:66)
- Collision tumors: 79 year old man with coexisting Merkel cell carcinoma (J Cutan Pathol 2008;35:203), 82 year old woman with coexisting basal cell carcinoma (Am J Dermatopathol 2005;27:319), with coexisting gastrointestinal stromal tumor (Am J Clin Dermatol 2012;13:64)
Treatment
- Excision with careful margin control (J Am Acad Dermatol 2008;58:142)
- Staged excision for peripheral margin control using permanent sections is required because frozen sections are unreliable (Plast Reconstr Surg 2007;120:1249)
- Possibly radiation (Surg Clin North Am 2003;83:323)
- Possibly imiquimod without (Ann Plast Surg 2008;61:419) or with surgery (Dermatol Surg 2008;34:147)
- Possibly cryotherapy
Dermoscopy
- Annular granular pattern (Br J Dermatol 2012;167:280), asymmetric pigmented follicular openings, dark rhomboidal structures and homogeneous areas
Dermoscopy Images
Images hosted on other servers:
Annular granular pattern
With slate gray dots
Typical dermoscopy features
Clinical images
Images hosted on other servers:
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
Images hosted on other servers:
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
- Desmoplastic melanoma: may arise secondary to lentigo maligna
- Lentiginous nevi
- Lentigo maligna in situ melanoma
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