What is a Mole? A mole, whose medical name is a melanocytic nevus, is an common benign growth of the color cells of the skin called melanocytes.

Moles normally appear in the first year of life and peak in number in the second or third decade, when the average number is 25. The total number of moles on the skin increases with significant sun exposure and in particular with sunburns before the age of 12. Some moles may disappear in the seventh to ninth decade.

The number of moles on your body is the strongest indicator for the risk of developing a malignant melanoma. There is also a direct relationship between the number of innocent moles on the skin and the chance of developing an abnormal or changing mole.

The number of moles on the arms is the greatest predictor of the number of moles present elsewhere on the body. Chronically sun exposed body sites have a higher density of moles, in particular small ones less than 5 mm in diameter. Larger moles are most prevalent on intermittently sun exposed areas, like the back and chest. Moles may increase in size, particularly before the age of 20. Normal moles are unlikely to enlarge as people get older. However, enlargement alone is not an indicator of malignancy or abnormality in a mole.

Here are two examples of patients with multiple atypical nevi:
Click on the thumbnail photo for a much larger image.

1. This patient has had malignant melanoma. His moles demonstrate the variation, size and appearance and color that are seen in patients who have multiple moles, and are at increased risk of developing malignant melanoma. These moles range in size from 1 mm to more than 1.5 cm. Some are irregular in color, and vary from light pink to dark brown. Most demonstrate symmetry.



2. This patient shows multiple large nevi, which have features of atypia. There is a large number of large nevi, with variation in appearance, which is a hallmark of patients at risk of melanoma.