| Lentigo maligna |
| Classification and external resources |
Micrograph of lentigo maligna showing the characteristic atypical epidermal melanocytes and solar damage in the superficial dermis. H&E stain. |
| ICD-10 |
C44, D03 (ILDS D03.L10) |
| ICD-O: |
8742/2 |
| DiseasesDB |
32059 |
| MeSH |
D018327 |
Lentigo maligna (also known as "Lentiginous melanoma on sun-damaged skin") is a melanoma in situ[1] that consists of malignant cells but does not show invasive growth.[2]:695 Lentigo maligna is not the same as lentigo maligna melanoma, and should be discussed separately. It typically progresses very slowly and can remain in a non-invasive form for years. The transition to true melanoma is marked by the appearance of a bumpy surface (itself a marker of vertical growth and invasion), at which point it is called lentigo maligna melanoma. It is normally found in the elderly (peak incidence in the 9th decade), on skin areas with high levels of sun exposure like the face and forearms. Some authors do not consider lentigo maligna to be a melanoma. It is commonly thought of as a melanoma precursor. Incidence of evolution to lentigo maligna melanoma is very low, about 2.2% to 5% in elderly patients.
It is also known as "Hutchinson's melanotic freckle".[3] This is named for Jonathan Hutchinson.[4][5]
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Contents
- 1 Presentation
- 2 Pathology Images
- 3 Diagnosis
- 4 Treatment
- 5 See also
- 6 References
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Presentation
Characteristics include a blue/black stain of skin initially. Skin is thin, about 4-5 cell layers thick, which is often related to aging. Histological features include epidermal atrophy and increased number of melanocytes.
Irregular patch about 10mm square after scrape biopsy which concluded "suspicious of early malignant melanoma". Colour before scrape biopsy was light brown. Post excision pathology was "Lentigo maligna - Melanoma in situ"
Pathology Images
See Wikimedia Commons for Lentigo Maligna images
Diagnosis
First dilemma in diagnosis is recognition. As lentigo malignas often present on severely sun damaged skin, it is frequently found amongst numerous pigmented lesions - thin seborrheic keratoses, lentigo senilis, lentigines. It is difficult to distinguish these lesions with the naked eye alone, and even with some difficulty using dermatoscopy. As the lentigo maligna is often very large, it often merges with, or encompasses other skin tumors - such as lentigines, melanocytic nevi, and seborrheic keratosis.
Second dilemma is the biopsy technique. Even though excisional biopsy (removing the entire lesion) is ideal, and advocated by pathologists; practical reason dictates that this should not be done. These tumors are often large and presenting on the facial area. Excision of such large tumor would be absolutely contraindicated if the lesion's identity is uncertain. The preferred method of diagnosis is by using a punch biopsy, allowing the physician to sample multiple full thickness pieces of the tumor at multiple sites. While one section of the tumor might show benign melanocytic nevus, another section might show features concerning of severe cellular atypia. When cellular atypia is noted, a pathologist might indicate that the entire lesion should be removed. It is at this point that one can comfortable remove the entire lesion, and thus confirming the final diagnosis of lentigo maligna. The size of the punch biopsy can vary from 1 mm to 2 mm, but it is preferred to use a punch 1.5 mm or larger. Representative samples of the most atypical parts of the nevus should be biopsied, often guided by dermatoscopy.
Treatment
Standard excision is still being done by most surgeons. Unfortunately, the recurrence rate is exceedingly high (up to 50%). This is due to the ill defined visible surgical margin, and the facial location of the lesions (often forcing the surgeon to use a narrow surgical margin). The use of dermatoscopy can significantly improve the surgeon's ability to identify the surgical margin. The narrow surgical margin used (smaller than the standard of care of 5 mm), combined with the limitation of the standard bread loafing technique of fixed tissue histology - result in a high "false negative" error rate, and frequent recurrences. Margin controlled (peripheral margins) is necessary to eliminate the false negative errors. If breadloafing is utilized, distances from sections should approach 0.1 mm to assure that the method approaches complete margin control.
Where the lesion is on the face and either large or 5mm margins are possible, a skin flap or skin graft may be indicated/required. Grafts have their own risks of failure and poor cosmetic outcomes. Flaps can require extensive incision resulting in long scars and may be better done by plastic surgeons (and possibly better again by those with extensive LM or "suspicious of early malignant melanoma" experience.
Scar 13 days after excision of coloured patch about 10mm square with 5mm margins from 1cm to right of base of nose. Length of incision required for skin flap to cover excision site. Scar should lighten and become finer for up to further 6 months if protected from sun.
Mohs surgery has been done with cure rate reported to be 77%.[6] The "double scalpel" peripheral margin controlled excision method approximates the Mohs method in margin control, but requires a pathologist intimately familiar with the complexity of managing the vertical margin on the thin peripheral sections and staining methods.[7]
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This section does not cite any references or sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (January 2009) |
Some melanocytic nevi, and melanoma-in-situ (lentigo maligna) have resolved with an experimental treatment, imiquimod (Aldara) topical cream, an immune enhancing agent. In view of the very poor cure rate with standard excision, some surgeons combine the two methods: surgical excision of the lesion, then three months treatment of the area with Imiquimod cream.
Studies seem to conflict about the level of certainty associated with using Imiquimod. Compare studies by Lena Li et al. [8] and A. M. Powell et al. [9]
Another treatment to be considered where standard margins cannot be achieved or cosmetics are a major consideration is ultra-soft x-ray/grenz-ray radiation.[10]
In the very elderly or those with otherwise limited life expectancy, the impact of major day surgery for excision with 5mm margins and large skin flap could be worse than the outcome of watchful waiting or the possibiity of failed treatments with Imiquimod or Grenz ray.
Some cities have specialist melanoma institutes such as the Melanoma Institute of Australia's Poche Centre in North Sydney, Australia.
See also
- Melanoma
- List of cutaneous conditions
References
- ^ McKenna JK, Florell SR, Goldman GD, Bowen GM (April 2006). "Lentigo maligna/lentigo maligna melanoma: current state of diagnosis and treatment". Dermatol Surg 32 (4): 493–504. doi:10.1111/j.1524-4725.2006.32102.x. PMID 16681656. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1076-0512&date=2006&volume=32&issue=4&spage=493.
- ^ James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0.
- ^ Green A, Little JH, Weedon D (January 1983). "The diagnosis of Hutchinson's melanotic freckle (lentigo maligna) in Queensland". Pathology 15 (1): 33–5. doi:10.3109/00313028309061399. PMID 6856341.
- ^ synd/1439 at Who Named It?
- ^ J. Hutchinson. Senile freckle with deep staining - a superficial epithelioma of the cheek. Archives of Surgery, London, 1892, 3: 159.
- ^ Mikhail, G. Mohs Micrographic Surgery. 1991, Saunders, pp. 13-14
- ^ Usefulness of the Staged Excision for Lentigo Maligna and Lentigo Maligna Melanoma: The 'Square' Procedure" (J Am Acad Dermatol 1997;37:758-63)
- ^ Li, Lena. "Efficacy of Imiquimod Cream, 5%, for Lentigo Maligna After Complete Excision". Archives of Dermatology. http://archderm.ama-assn.org/cgi/content/abstract/147/10/1191. Retrieved 2 November 2011.
- ^ Powell, A. M.. "Imiquimod and lentigo maligna: a search for prognostic features in a clinicopathological study with long-term follow-up". British Journal of Dermatology. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2133.2009.09032.x/pdf. Retrieved 2 November 2011.
- ^ Hedblad, Mari-Anne. "Grenz ray treatment of lentigo maligna and early lentigo maligna melanoma". Journal of the American Academy of Dermatology. http://www.sciencedirect.com/science/article/pii/S0190962211008371. Retrieved 2 November 2011.
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Tumors: Skin neoplasm, Nevi and melanomas (C43/D22, 172/216, ICD-O 8720-8799)
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| Melanoma |
Mucosal melanoma · Superficial spreading melanoma · Nodular melanoma · lentigo (Lentigo maligna/Lentigo maligna melanoma, Acral lentiginous melanoma)
Amelanotic melanoma · Desmoplastic melanoma · Melanoma with features of a Spitz nevus · Melanoma with small nevus-like cells · Polypoid melanoma · Nevoid melanoma
Melanocytic tumors of uncertain malignant potential
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Nevus/
melanocytic nevus |
Nevus of Ito/Nevus of Ota · Compound nevus · Spitz nevus (Pigmented spindle cell nevus) · Halo nevus · Junctional nevus · Pseudomelanoma
Blue nevus (Blue nevus of Jadassohn–Tièche, Cellular blue nevus, Epithelioid blue nevus, Deep penetrating nevus, Amelanotic blue nevus, Malignant blue nevus)
Congenital melanocytic nevus (Giant pigmented nevus, Medium-sized congenital nevocytic nevus, Small-sized congenital nevocytic nevus)
Balloon cell nevus · Dysplastic nevus/Dysplastic nevus syndrome
Acral nevus · Becker's nevus · Benign melanocytic nevus · Nevus spilus
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noco (i/b/d/q/u/r/p/m/k/v/f)/cong/tumr (n/e/d), sysi/epon
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proc, drug (D2/3/4/5/8/11)
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