Seeing spots? Employ the ABCD rule

According to the Centers for Disease Control and Prevention, skin cancer is the most common form of cancer in the United States.

The American Cancer Society reports that most skin cancers can be found early with skin exams. And regular exams by your doctor and checking your own skin frequently can help find cancers early, when they are easier to treat.

The Society offers the following advice for early detection:

The most important warning sign for melanoma is a new spot on the skin or a spot that is changing in size, shape, or color.

Another important sign is a spot that looks different from all of the other spots on your skin (known as the ugly duckling sign). If you have any of these warning signs, have your skin checked by a doctor.

The ABCD rule is another guide to the usual signs of melanoma. Be on the lookout and tell your doctor about spots that have any of the following features:

A is for asymmetry: One half of a mole or birthmark does not match the other.

B is for border: The edges are irregular, ragged, notched, or blurred.

C is for color: The color is not the same all over and may include shades of brown or black, or sometimes with patches of pink, red, white, or blue.

D is for diameter: The spot is larger than 6 millimeters across (about ¼ inch — the size of a pencil eraser), although melanomas can sometimes be smaller than this.

Some melanomas do not fit the rules described above, so it is important to tell your doctor about any changes in skin lesions, new skin lesions, or growths that look different from the rest of your moles.

Other warning signs are:

A sore that does not heal

Spread of pigment from the border of a spot to surrounding skin

Redness or a new swelling beyond the border

Change in sensation — itchiness, tenderness, or pain

Change in the surface of a mole — scaliness, oozing, bleeding or the appearance of a bump or nodule