The ABCDs of Melanoma

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ABCD Defined

Mole on skin
BSIP/UIG/Getty Images

Melanoma is the most deadly of all skin cancers. An estimated 46,000 Americans will develop melanoma every year, and 7,700 Americans will die from it every year.

Skin Self-Examination

It's important to know how to recognize the early warning signs of melanoma. You should examine your skin frequently to get used to the appearance of your moles. Follow the ABCD's below to identify any abnormal moles.

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Asymmetry - Normal Mole

A normal mole is symmetrical - one-half of the mole matches the other half in size, shape, color, and thickness. In this picture, you can see that any way you cut this mole in half, both sides will have the same characteristics.

Other normal characteristics of this mole include:

  • Border - The border of this lesion is distinct and not scalloped or notched.
  • Color - This lesion is flesh colored and does have some red in it. However, the redness is consistent throughout the lesion.

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Asymmetry - Melanoma

Asymmetry is one sign that a mole is not normal. A lesion is asymmetric if half of the mole does not match the other in size, shape, color, or thickness. In this picture of melanoma, you can see that the left side of the lesion is much thicker than the right side.

Other atypical features of this mole include:

  • Border - Even though the border is distinct throughout the lesion, the border on the top half is scalloped and notched.
  • Color - The color is inconsistent. The left side is black and the right side is brown.

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Border - Normal Mole

A normal mole has well-defined, regular borders. In this picture, even though the mole is a darker color, the border between mole and normal skin is distinct and consistent -- not ragged or scalloped.

Other normal features of this mole include:

  • Symmetry - If you cut this mole in half, each halve would have the same color, shape, and thickness.
  • Color - This mole is a consistent brown throughout.

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Border - Melanoma

The border of melanoma can be ragged, scalloped, blurred, or poorly defined. In this picture of melanoma, you can see that the border is scalloped or notched throughout.

Other abnormal features seen in this picture include:

  • Asymmetry - If you cut this lesion in half, the halves would not match in thickness, color, or shape.
  • Color - This lesion has areas that are red and other areas that are back. The color is inconsistent throughout the lesion.

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Color - Normal Mole

Normal mole color should be the same throughout and not have shades of tan, brown, black, red, white or blue. Many benign lesions do not meet this criteria, but that determination is best left to your dermatologist. In this picture, you can see that the mole is consistently brown. It does have some reddish features, but they are consistent throughout the lesion.

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Color - Melanoma

The color of melanoma is not consistent throughout the lesion and can be shades of tan, brown, black, red, white, or blue. In this picture, you can see that the color is definitely not consistent throughout. The right side of the lesion is dark black and the left side is tannish-red.

Other abnormal features seen in this picture include:

  • Asymmetry - If you cut this lesion in half, the halves would not match in thickness, color, or shape.
  • Border - This is also a good example of indistinct borders -- especially on the top of the lesion. It also has scalloped edges and notching on the bottom left.

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Diameter - Normal Mole

A normal mole can be any size but typically lesions less than 6 mm are less concerning for melanoma. This is a small mole that has other features of normal moles:

  • Symmetry - If you cut this lesion in half, both sides would match in color, thickness, and shape.
  • Border - The borders of this lesion are very distinct and not scalloped or notched.
  • Color - The color is consistent throughout the mole.

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Diameter - Melanoma

The diameter of melanomas is usually greater than 6 mm. You can see in this picture that this lesion on the cheek is definitely larger than 6 mm.

Other abnormal features of this lesion include:

  • Asymmetry - If you cut this lesion in half, the halves would not look the same in color, size, and thickness.
  • Border - The border of this lesion is wavy and scalloped especially on the left. The border on the right side of the lesion is indistinct.

Sources

Barnhill, Raymond and Keith Llewellyn. "Benign Melanocytic Neoplasms." Dermatology. Ed. Jean L Bolognia, MD, et al. London: Mosby, 2003. 1768-70.

Habif, Thomas. "Nevi and Malignant Melanoma." Clinical Dermatology, 3rd ed. St. Louis: Mosby, 1996. 688-692.

"How to Perform a Self-Examination." American Academy of Dermatology. 2006. American Academy of Dermatology. 4 May 2007.

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