Melanoma: Symptoms and Signs

Approved by the Cancer.Net Editorial Board, 12/2021

ON THIS PAGE: You will find out more about changes and other things that can signal a problem that may need medical care. Use the menu to see other pages.

"ABCDE" rule

Changes in the size, shape, color, or feel of a mole are often the first warning signs of melanoma. These changes can occur in an existing mole, or melanoma may appear as a new or unusual-looking mole. The "ABCDE" rule is helpful in remembering the warning signs of melanoma:

  • Asymmetry. The shape of one-half of the mole does not match the other.

  • Border. The edges are ragged, notched, uneven, or blurred.

  • Color. Shades of black, brown, and tan may be present. Areas of white, gray, red, or blue may also be seen.

  • Diameter. The diameter is usually larger than 6 millimeters (mm) or has grown in size. This is about 1/4 inch in diameter, about the size of a pencil eraser. Melanoma may be smaller when it is first detected.

  • Evolving. The mole has been changing in size, shape, color, or appearance, or it is growing in an area of previously normal skin. Also, when melanoma develops in an existing mole, the texture of the mole may change and become hard or lumpy. The skin lesion may feel different and may itch, ooze, or bleed, but a melanoma skin lesion usually does not cause pain.

When to see a doctor

Many melanomas are dark brown or black and are often described as changing, different, unusual, or “ugly looking,” meaning that it looks different from the typical moles a person has. However, any skin abnormality that is growing or changing quickly and does not go away, whether colored or not, should be examined by a doctor. Bleeding may be a sign of more advanced melanoma. In addition, the appearance of a new and unusual mole is more likely to be melanoma.

If you are concerned about a new or existing mole, please talk with your family doctor or a dermatologist. Your doctor will ask how long and how often you’ve been experiencing the symptom(s), in addition to other questions, and examine the mole. This is to help figure out the cause of the problem, called a diagnosis, and whether a biopsy is recommended.

The next section in this guide is Diagnosis. It explains what tests may be needed to learn more about the cause of the symptoms. Use the menu to choose a different section to read in this guide.