Moles appear during the first 20 years of life, although some may not appear until later in life.
Moles are not stable. They can grow and go through changes of maturation. Flat junctional nevi may be present at birth, but usually appear between 3 and 18 years of age. They vary in size and shape, and may have a fried-egg appearance with darker bulls-eye center. They grow in proportion to body growth during childhood and adolescence. During adolescence and adulthood, they may become raised compound or intradermal nevi. Moles may darken with exposure to sun, birth control pills, and pregnancy. This is a normal occurrence.
The signs of benign nevi are uniform pigmentation, smooth regular border, and unchanging size and color.
The signs of malignant transformation are the ABCDs. A is for asymmetry of 2 halves of the nevus (benign lesions have two halves in any orientation that show symmetry). B is for border - irregular or scalloped border and signs of satellite pigmentation. C is for color changes or variegation in color, especially red, white, gray, or blue. D is for diameter, with diameter of greater than 6 mm more concerning. Other signs include enlarging size or surface changes such as scaling, erosion, oozing, crusting, ulceration, or bleeding.
The "ugly duckling" sign refers to a mole that looks different from the majority of other moles and should be removed to evaluate for melanoma. Clinically atypical nevi are less likely to be melanoma if other nevi on the same patient share similar features. If the patient has one mole different from all others, you might remove it by shaving or excision. But if a mole has "cousins" that look similar, the risk of cancer is low.
- If a mole looks suspicious for melanoma, remove the mole with 2 mm margins. The lesion must be sent to Pathology.
- If the lesion turns out to be a melanoma, not to worry as studies indicate there is no detectable risk of causing melanoma to metastasize by performing a shave or punch biopsy.
- The pathology report may show normal (junctional, compound, or intradermal) nevi, various levels of atypia (slight, moderate, severe), or melanoma. Atypia is a precursor to melanoma, but is not yet melanoma.
- If a mole is normal, no further treatment is needed.
- If a mole shows slight or moderate atypia and margins are clear, no further treatment is needed. Patient should be asked to look for recurrence of pigment.
- If a mole shows slight or moderate atypia and margins are not clear, re-excise or re-shave to get around the lesion.
- If a mole shows marked or severe atypia or any degree of pathologist's concern for melanoma, please refer to Skin Cancer and Dermatology (SCAD) clinic for further evaluation. If pathology states melanoma, refer to Melanoma Clinic in the Cancer Center.
There are so many moles in the world! To preserve appointments for patients who need dermatologic consultations, UM Dermatology does not accept patients for routine "mole checks" or "skin checks". Patients’ personal physicians are the best source for such evaluations.