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Melanoma - What is it?

By Cynthia Bailey MD. This page was updated on Tue, Sep 19, 2017

Melanoma is a skin cancer of the cells called melanocytes. These cells are responsible for your skin color. These same cells form moles. In moles, melanocytes are clumped into bunches (called nests) in the epidermis, dermis (second living layer of skin), and in the fat (subcutis). Melanocytes are not the cells that make up the epidermis. The epidermis is made up of layers of cells called keratinocytes. Keratinocytes can also become cancerous. These cancers are called Basal Cell Carcinoma and Squamous Cell Carcinoma. Precancerous growths of keratinocytes are called Actinic Keratosis. The distinction between keratinocytes and melanocytes is important because their cancers are entirely different – like apples and bananas. They are unrelated and one does not become the other. Melanocytes are clumped in nests in your moles. Melanocytes are also present in the central nervous system (spine, brain, and eyes), inner ear, and the heart. Melanoma cancer is caused when one of these cells mutates and grows uncontrollably. UV rays are one of the significant causes of melanocyte cell mutation. UV ray exposure is also preventable. Melanoma is deadly and the occurrences are increasing. It can even affect children and young adults. If not caught early, it will spread through the body. As a dermatologist, I am passionately dedicated to preventing melanoma and catching it early. This mission saves lives. As part of this personal mission, I educate people on UV ray skin exposure and early detection of melanoma. The cancer is much less likely to be deadly and treatment is easier in the early stages.


You are more likely to get melanoma if you:
  • have fair skin, especially if you or your parents have red hair or are blond and/or have blue green eyes.
  • have a history of blistering sunburns. 5 or more sunburns between ages 15-20 increases your risk by 80%.
  • have many moles or if your moles are large and irregular (dysplastic nevi).
  • have a history of unprotected sun exposure.
  • have used a tanning bed.
  • have a relative who has had melanoma.
  • are in the upper middle-class (curious, right?!)
Whether you are at high risk or not, do monthly self-skin exams to keep an inventory of their ‘spot collection’. It’s best done with a mirror. The goal is to get a general impression of your spots and be certain they are not changing. Spouses, partners, and parents may be needed to help examine your back.

Screen for Melanoma

We teach to look for these 5 worrisome signs: ABCDE’s of Melanoma. A: Asymmetry
  • This refers to when moles are irregularly shaped - not round or oval.
B: Border
  • A melanoma sign is when the mole’s edges are jagged, blends into skin, notched, or scalloped.
C: Color
  • Be wary when the color throughout a mole is not uniform.
D: Diameter
  • Measure if the diameter of a mole is greater than 6 mm (approximately the size of a pencil eraser).
  • You may identify melanomas smaller than 6 mm.
E: Evolving over Time
  • Examine if the mole is raised or not flush with your skin.
  • Does the mole become tender or ulcerate?
  • Watch if the mole changes over time in size or color (darker, lighter, red, blue, black, white – it all counts).
There is also the Ugly Duckling Sign. The Ugly Duckling Sign is a mole that does not match your other moles. For example, your moles may be light brown with an exception of a black mole. That would need to be evaluated by an expert during your full skin exam. Other odd patterns may be your moles are all dark and one is lighter, red, or has a white circle around it. Schedule an appointment with a Board-Certified Dermatologist if you suspect one of the moles on your body may be melanoma. A full skin exam is painless and I can’t tell you how many times a patient has saved their life by scheduling one!

Do All Melanomas Come from Moles?

The surprising answer is no! In a vital scientific study, it was found that only one-third of melanomas arise from existing moles. The vast majority of melanoma cancers appear on the skin as new spots according to the study published in the Journal of the American Academy of Dermatology. These investigators reviewed 38 published studies comprising 20,126 melanomas. They found that less than one-third of melanomas (29%) arose from an existing mole. The vast majority (71%) appeared as new spots. Melanomas that arose from existing moles were thinner, indicating that patients whose melanoma was associated with an established mole had a better prognosis. We don’t know why this is.

Melanoma Identification – Practical Examples

Here is an example of how to identify melanoma using the ABCDE’s. Melanoma #1 A: Not perfectly oval. B: Poorly-defined margins. Some margins are very dark, while others are light and blend into the skin C: Color not uniform. Dark red in some areas, lighter in others. White area in the center. D: Diameter not given and unable to measure from photo. E: Elevation noted in the center with possible scab indicating possible bleeding. Melanoma #2 A: Asymmetrical. No clear shape. B: Border clearly defined but ragged. Scalloped in some areas. C: Distinct color variations. A dark reddish-purple border outlines the mole with a white center. It’s also paler than regular skin tone. D: Diameter not given and unable to measure from photo. E: Dark border appears slightly elevated, irregular, and texturized.

Contributing Factors That Increase the Risk of Melanoma?

1.  UV rays: We know UV rays damage DNA. Both regular and intermittent exposure to the sun contributes to sunburns and melanoma. Damaged DNA sometimes “turns on” an oncogene (a gene that causes a tumor cell) or “turns off” a tumor suppressor gene (a gene that usually stops the uninhibited growth of cells), which opens the door for cancer to develop. It’s essential to protect from UV damage by wearing sunscreen every day. 2.  Geography: Since UV rays damage DNA, it makes sense that more intense sun would cause more severe damage. People who live close to the equator as well as those living at high altitudes get more intense sun exposure and have an increased risk of melanoma. 3.  Family history:  Melanoma can be labeled “familial” when two or more first-degree relatives have had melanoma. When there are alterations in one of two specific genes (named CDKN2A or CDK4), people are at risk for this type of melanoma. Individuals with familial melanoma often have “funny looking moles” which is known as “atypical mole syndrome,” a condition in which moles may appear irregular looking and are sometimes difficult to visually distinguish from melanoma. When melanoma runs in your family or you have many unusual looking moles, it is critical to see a board-certified dermatologist for regular skin checks. 4.  The number of moles and freckles: Having many moles increases the risk of developing melanoma. Over 100 moles can increase your risk 10x. Having lots of freckles is also a risk factor. 5.  Skin type: Melanoma is more common in Caucasians, particularly in fair-skinned people. Redheads with light eyes seem particularly susceptible. This does not mean that darker-skinned people can’t get melanoma, but it is less common.

Bottom Line

Anyone can develop skin cancer, including melanoma. 1 in 50 Americans are estimated to develop melanoma during their lifetime.
  • Melanoma is caused mainly by intense, occasional UV exposure (frequently leading to sunburn), especially in those who are genetically predisposed to the disease.
  • It kills an estimated 9,940 people in the US annually; one person dies of melanoma every hour (every 57 minutes).
  • It is not the most common of the skin cancers but it causes the most deaths.
  • Melanoma is one of only three cancers with an increasing mortality rate for men, along with liver cancer and esophageal cancer.
  • Women aged 39 and under have a higher probability of developing melanoma than any other cancer except breast cancer.
  • Each person with a first-degree relative diagnosed with melanoma has a 50 percent greater chance of developing the disease than people who do not have a family history of the disease.

Patient Care

My job as a dermatologist is to help prevent melanoma or early detection. I perform a full body exam and teach patients that most melanoma comes from new moles. New moles after the age of 30 need to be given attention as does any changes in existing moles. I teach patients to do monthly self-exams and become familiar with their general inventory of moles. This includes scalp, between toes etc. For the back, enlist the help of a loved ones. When a person has more moles than I can document on a written map, I capture total mole map photos and compare them during exams. I teach patients the foundation of assessing their moles and the Ugly Duckling Sign. If a mole itches, develops a white halo, or turns into a scab or sore, come show me. It is comforting to have a strategy and a healthy amount of suspicion. Pay attention to even a tiny change. In my years of dermatology practice, I have had patients detect their own melanoma simply because of a hunch. Because early detection is lifesaving, an open-mind during skin exams is essential. I also educate on effective sun protection techniques. Being outside is a pleasure and doing it without UV mutation is possible. Click here for my sun protection tips refined by my patients and I.