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One of every 57 Americans will be afflicted with melanoma (or one in 33, if noninvasive melanoma in situ is included), with one person per hour dying of the disease.1 Melanoma in men is increasing more rapidly than any other malignancy, and in women it is the second most rapidly increasing malignancy, after lung cancer. 2 Even these estimates may be low because melanomas treated in the private outpatient setting are often not reported.3
Melanoma incidence has increased significantly over the past several decades. Predictions forecast a doubling of melanoma rates every 10 to 20 years, making melanoma the most rapidly increasing cancer in white populations.4
So, who needs to be screened? The answer is: everyone. It is widely believed that the total risk factor for melanoma is determined by the interplay between genetic factors and environmental factors, such as exposure to ultraviolet (UV) light.4
Studies suggest that a sunburn during childhood may be a more important risk factor for melanoma than is sunburn as an adult.5 This is an important point for family practice, pediatrics, and obstetrics/gynecology clinicians, who can educate parents on the dangers that sunburns during our youth can pose to long-term health.
Pigmentation and skin reaction to sun also are risk factors for melanoma.6 In addition, the World Health Organization’s International Agency for Research on Cancer categorized tanning beds as “a human carcinogen.” 4
Melanoma risk factors
The following factors put a person at particularly high risk for melanoma and merit more frequent skin examinations by the provider and by the patients themselves, consideration for referral to a dermatologist for skin surveillance, and direct patient education using smart sun-protection methods:
- Family history of melanoma especially for patients who have a first-degree relative with melanoma
- Lightly pigmented skin
- Tendency to burn/inability to tan
- Intense intermittent sun exposure, regardless of whether sunburns are incurred during that exposure
- Chronic sun exposure
- Tanning bed use, especially before age 35 years
- Multiple moles (greater than 60)
- Atypical or dysplastic nevi
- Presence of lentigos (a sign of prior overexposure to UV light)
- History of melanoma
- History of nonmelanoma skin cancer, such as basal cell or squamous cell skin cancer.7
The skin examination
As a general rule, patients should undergo a baseline skin examination with a dermatology provider, and then ask that provider how frequently future screening should be done as determined by the patient’s skin type, family history, lifestyle, and findings during that initial examination.
Yearly is a conservative schedule for someone who is fair, has a family history of skin cancer, or has a history of actinic damage. Someone lacking any risk factors could need a clinical examination as infrequently as once every three years.
When conducting a skin examination, providers should look for much the same signs they should advise patients to note when performing a skin self-examination. Clinicians can cover the patient-education piece while performing the clinical skin examination. Showing the patient an example of a finding or nonfinding on the patient’s own skin will further drive home the information.
The ABCDEs of skin cancer screening are as follows:
Asymmetry. An asymmetric lesion raises the index of concern. Does an imaginary line drawn down the center of the lesion create a mirror image of the two sides? If not, then the lesion is asymmetric.
Border. A scalloped, irregular, paisley-like, or vague border should raise the index of concern.
Color. The lesion should be the same color throughout. The clinician should not see different shades of brown and certainly no black, red, or blue.
Diameter. As a general rule, melanomas usually are larger than 6 mm. (Explain to patients that 6 mm is approximately the size of the eraser end of a Number 2 pencil.) In reality, many melanomas are much smaller than 6 mm, particularly when the lesion is detected early in its development.
Evolution. At one time, the ABCD mnemonic had no “E.” But a new or changing lesion should raise an immediate concern for a skin cancer risk. Change (or evolution) in size, shape, elevation, or color of a mole should be evaluated immediately.
Early detection of melanoma also can be aided by both the practitioner’s and the patient’s attention to the so-called ugly duckling syndrome — one lesion that clearly stands out from the rest raises the index of concern.
For example, one particular lesion on the skin may be much darker or bigger than the rest. During a first glance at a particular part of the body, one lesion may instantly jump out at the clinician as being atypical.
One dermatologist reports a practice in which he routinely quickly glances at a patient’s skin before turning away, then asking himself whether there was a spot that stood out during that brief initial look. A skin lesion that is clearly an outlier is significant cause for concern.
Start the clinical examination by evaluating any lesion brought to the provider’s attention by the patient, so that the patient’s concern does not get lost in the end-of-appointment rush. The clinician should then perform a full skin examination, following his or her own pattern or sequence of body areas to examine. This pattern should become habit so that the provider never misses an area of the patient’s body, from the scalp to between the toes and the bottom of the feet.
Many dermatology providers, including this author, use a dermatoscope to aid the skin examination. These instruments light up and magnify pigmented lesions and help illuminate benign lesions such as seborrheic keratosis and hemangioma.
Lesions of concern
If a lesion of concern is discovered, it should be measured and documented. Photographing it can also help both the practitioner and the patient monitor the lesion for growth or other changes. Electronic medical records may provide a relatively easy location for storing such images.
Providers who feel that biopsy is in order should use a lab that has a dermatopathologist rather than a general pathologist available to read the slide. Pigmented lesions and skin biopsies in general are difficult specimens to evaluate histologically.
If the index of concern for a melanoma is high, a punch or excisional biopsy is ideal for measuring depth and allowing for evaluation of the entire lesion. If the lesion is too large to biopsy in that fashion, then a wide, deep, “scoop biopsy,” also known as a tangential biopsy or a saucerization, should be done for the entire lesion. A biopsy performed on only one small portion of a large lesion may not be representative of the entire histology or future of the lesion.
Melanoma types and staging
The various types of melanomas include superficial spreading malignant melanoma, lentigo maligna melanoma, nodular malignant melanoma, acral lentiginous melanoma, ocular melanoma and malignant melanoma on mucous membranes.
Superficial spreading melanoma is the most common in ethnically white individuals, occurring most frequently on the trunk in men and on the legs in women. Superficial spreading melanomas follow the most typical pattern of failing the ABCDE guidelines.
Nodular melanoma is the second most common type of melanoma. These lesions are found in white patients, most commonly those in their sixth decade of life. Nodular melanomas are thick and have the potential to progress and metastasize rapidly. These lesions can be nonpigmented (amelanotic).
This fact highlights the point that any fast-growing new lesion, even one without pigment, should be evaluated and at least monitored, if not biopsied. Ulceration and bleeding of the amelanotic lesions can be clues to the diagnosis.1
Lentigo maligna melanoma tends to occur on chronically sun-exposed skin such as the head, neck, and arms. Acral lentiginous melanoma appears on the palms, soles, and nail beds, and is more commonly seen among non-white persons than among whites. This is also true for melanoma under the nail bed, a rare disease that appears as brown or black linear pigmentation. Involvement of the proximal nail fold or nail bed, called the Hutchinson sign, is a hallmark for subungual melanoma.
Various rare melanoma subtypes exist and include melanomas that develop in the eye or other internal locations.
A pathology report will include different measurements in the staging of a melanoma. The stage determines the treatment and is a prognostic factor.
A good pathology report on a melanoma should provide at least the following information: diagnosis, tumor site, histologic subtype, Clark level, growth phase, greatest thickness, presence of ulceration or regression, mitotic rate, presence of blood vessel/lymphatic invasion, margins, and presence of any microscopic satellite lesions, plus a description of what was seen under the microscope.