By Gary M. White, MD
Multiple colors including dark black, an irregular edge, and diameter > 6 mm.
Melanoma is a potentially fatal neoplasm of the skin originating from melanocytes. It is the most deadly of the common skin cancers and its incidence is on the rise. However, in countries with aggressive sunscreen use (e.g., Australia), rates may be leveling off.
Various melanoma variants occur including:
The term familial atypical multiple mole melanoma syndrome describes those patients with a personal and/or family history of melanoma and multiple clinically atypical nevi. Rarely, vitiligo-like lesions may accompany the diagnosis of melanoma.
The average lifetime risk of a person born in the US today to develop a melanoma is as follows:
|Non-Hispanic Caucasian male||1 in 41|
|Non-Hispanic Caucasian female||1 in 61|
|Hispanic||1 in 200|
|Asian and Black||1 in 1000|
The following table tries to quantify the risk for various factors [much of the data from J of Cancer Treatment and Research 2016;4;1]. A relative risk (RR) of 2 means double the risk. An RR of 1.5 means a 50% elevated risk.
|Personal history of and a parent with melanoma||30|
|Personal history of melanoma||9|
|Two or more first degree relatives with melanoma||5.5|
|Over 100 moles||5|
|Red hair (compared with dark hair)||3|
|Always burns, never tans||2.3|
|One first degree relative with melanoma||2.24|
|Prior use of Viagra (for men)||2.2|
|The presence of 2 large (dysplastic) nevi||2|
|Airline pilot or crew||2|
|History of BCC or SCC||2|
|History of 10 or more severe sunburns||2|
|Usually burns, tans some||2|
|Blonde hair (compared with dark hair)||2|
Other factors that increase risk include:
In a study of melanoma in the US from 1975-2006 [Cancer Epidemiol Biomarkers Prev. 2010;19:2401], the specific body site distribution was as follows:
In another study of patients at high risk for melanoma [JAMA Derm 2017;153;23], those with many nevi were more likely to have melanoma on the trunk, those with a family history of melanoma were more likely to have melanoma on the limbs and those with a personal history were more likely to have melanoma on the head and neck.
Most melanomas have some darkly pigmented area--black or dark brown. This is not always true however, as some melanomas are amelanotic. Still, the typical dark black, brown, or two-toned nevus, usually flat, and > 6 mm is most suspect. When doing a complete skin exam, look for the lesion that is larger, darker, and more irregularly shaped than all the other moles--the so-called ugly duckling sign. Rarely, a melanoma may develop a halo (see halo melanoma).
Every health care practitioner should be well-versed in the ABCDE's of melanoma. S/he should be able to recognize a suspicious lesion and either provide appropriate initial care or quickly refer the patient. Any lesion that satisfies two of the following should be biopsied:
A Asymmetric shape B Border, irregular C Colors, multiple or dark black D Diameter, 7 mm. or greater E Evolving
Any lesion with 2 or more should be removed [JAAD 2015;72;717]. See also abcde criteria.
A slightly simplified ABCDE criteria has been designed for patients and used in a structured skin self-examination study [JAMA Derm 2016;152;979]:
|Border||Smooth||Jagged pointed projection(s)|
|Color||1-2 colors, uniformly distributed||More than 3 colors, non-uniform distribution|
|Diameter||4 mm. or less||6 mm or greater|
Patients were told to seek medical attention for any mole that was abnormal in all 3 features or that changed from normal to abnormal in any of the features. Note: in one study, no melanomas with a diameter of less than 5 mm recurred or metastasized [Ann Surg 1970;172;902].
Approximately 30% of melanomas are associated with a nevus. One study showed that association with a preexisting nevus has no prognostic implication for sentinel lymph node status or overall survival [JAAD 2015;72;54]. However, another study [J Natl Cancer Inst 2016;108(10)] found that de novo melanomas were more often thicker, ulcerated and associated with shorter overall survival.
For issues with regard to total body skin examination, see here. Total body photography (TBP) is sometimes indicated, especially in a patient with a large number of nevi. However, TBP, as of this writing, has not been shown in clinical trials to reduce mortality. In terms of screening the population at large, education of all clinicians, nurses, and patients themselves is beneficial.
Complete excision is most likely to give an accurate diagnosis. Shave biopsy is second best and punch biopsy is most likely to result in misdiagnosis [Arch Dermatol. 2010 Mar;146(3):234-9]. Deep shave (scoop) biopsies are appropriate for some locations and have the advantage of being able to be done the same day. The depth of the biopsy should be sufficient to get all the pigment. Although it is preferable to remove a clinically atypical pigmented lesion in its entirety, at times a partial biopsy may need to be made when the lesion is large, e.g., >= 2 cm and in a cosmetically sensitive area, e.g., the face. Remember though that a partial biopsy may miss the melanoma. If the biopsy comes back benign and clinical suspicion is high, rebiopsy is indicated.
A recent review concluded that the original Breslow's depth of transected melanomas without residual tumor on re-excision accurately predicts survival and prognosis [Dermatol Surg. 2013 Apr;39(4):605-15].
If a solitary lesion is biopsied and there is a melanoma in the dermis without an epidermal component, consider the following:
See melanoma treatment pathway.
Melanomas on the ear.
Melanoma arising from a preexisting mole (lighter brown color).
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