Benign lesions tend to maintain a uniform appearance, while malignant melanomas tend to be asymmetric, have irregular borders, and often are associated with changes in color. This has been taught to medical students as the ABCs of melanoma. They occur more commonly in light skin individuals and darken with sun exposure. These lesions reflect melanocyte overactivity, not proliferation. They usually appear in childhood, are unaffected by sun exposure, and are associated with Peutz-Jeghers syndrome.
Lesions usually have irregular borders and slowly increase in size.
It most commonly occurs on the sides of the face, the forehead, the upper lip, the chin, and the sides of the neck. Frequently, melasma is associated with pregnancy or the use of oral contraceptives, but melasma can occur in men. Most pregnancy-associated cases fade away following delivery, eventually clearing within a few months. Lesions typically present in childhood as small, flat tan macules that increase in size. They are elevated slightly and pigmented.