By Gary M. White, MD
Acquired melanocytic nevi--or moles--are common, benign growths of the skin. It is critical for patients to be aware of their moles and seek attention if any develop signs of melanoma. In addition, many patients seek removal of these lesions for functional or cosmetic reasons.
See also atypical mole syndrome, eclipse, blue, congenital, vulva and halo.
Nevomelanocytic nevi come in all shapes and sizes. Early in their life cycle, they tend to be flat and dark. As the patient ages, the nevi tend to raise up and lose their color. Late in life, nevi may disappear altogether. Nevi are common on the upper back, probably because that area gets significant sun exposure. In one study, nevi were most common on the outer forearms, followed by the outer upper arms, neck and face. Larger nevi were most prevalent on the intermittently exposed skin of the trunk. In studies that count nevi, the peak age for the most number of nevi ranges from 30-40 years of age.
It has been suggested to define more clearly the terms used to describe pigmented lesions, much the way radiologists have unified their terminology [JAMA Derm 2017;153;973].
It seems like further terms describing how raised (or flat) the lesion is would be in order.
All pigmented lesions should be evaluated by the ABCDE criteria and removed if abnormal. Patients should protect themselves from the sun. Any clinically benign nevus removed for cosmetic or functional reasons should be submitted for pathologic examination to exclude malignancy. In a study of such lesions, 2.3% were found to represent a malignancy (melanoma, BCC and SCC) [JAAD 1999;40;567]. In a study of over a thousand nevi, enlargement alone (without signs of atypia) was not a sign of malignancy. For pathology reports that show some amount of histologic atypia, see nevus, atypical.
Any lesion with 2 or more of the following should be removed. See also ABCDE criteria and atypical nevi.
Many patients ask if moles can be removed with laser. Even if laser therapy is able to remove a nevus, such an approach would not provide histologic analysis.
One study found an incidence of 3.5% of genital nevi in children and no increased incidence of melanoma [JAAD 2014;70:429-34].
Intradermal nevi are least likely to result in melanoma as they do not have a junctional component. Although extremely rare, malignant transformation can occur [Dermatology. 1998;196(4):425-6].
Benign Mole on the Palm
Biopsy-proven nevus on the toe.
Moles may occasionally become inflamed. This patient presented with a mole that had suddenly changed--in this case more red and tender. Biopsy showed intradermal nevus with acute folliculitis.
The presence of many moles is a risk factor for melanoma. Such patients should have an annual total body skin examination.
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