Melanoma is a potentially serious type of skin cancer that develops from normal skin cells called melanocytes (these cells produce the skin pigment melanin, which gives the skin its natural colour).
The cells become malignant and start growing uncontrollably, subsequently aggressively invading surrounding healthy tissues.
This cancer can develop in a mole or other mark on the skin, but also often develops in unmarked skin.
Commonly, it starts on the upper back or trunk of men and women, and the legs in women, but it can occur anywhere. Melanoma is most common in light-skinned people, but affects people of all races.
Type of melanoma
These often differ in location and frequency in the body and, at one time, the four types were considered to carry different levels of risk. But recent guidelines on risk now show that one type of melanoma isn’t necessarily more dangerous than another.
The four types of melanoma are as follows:
1. Lentigo-malignant melanoma
This appears mostly on the face of elderly people as an asymptomatic, large (2 to 6 cm), flat, tan or brown disc with darker brown or black spots scattered on the surface.
2. Superficial spreading melanoma
This is initially much smaller than the lentigo-malignant melanoma and occurs most commonly on women’s legs and men’s torsos.
3. Nodular melanoma
This may occur anywhere on the body as dark, protuberant papules or a plaque that varies in colour from pearl to grey to black.
4. Acrolentiginous melanoma
This is most common in black races, and arises on the surface of hands or feet, or underneath nails.
Melanoma is the third most common form of cancer in Australia. And, while it makes up only 2.3% of all skin cancers in this country, it’s responsible for a staggering 75% of skin cancer-related deaths.
The incidence of melanoma has risen dramatically worldwide in the last 40 years, yet the morbidity (death rate) has dropped significantly due to early detection.
In older people, the risk of developing melanoma is higher but it can affect even young children.
The early signs of melanoma can be a change in a mole or similar pigmented lesion. These include changes in:
- Colour, especially darkening or turning black, brown, white, red or blue. It is also possible that part of a mole will lose colour (regression).
- Colour distribution, especially spread of colour from the edge of a mole into surrounding skin
- Size, especially rapid growth
- Shape, especially when irregular borders appear
- Elevation – when a previously flat mole thickens or becomes raised above the rest of the skin
- Surface, especially erosion, scaling, indentations, oozing, bleeding or crusting
- Surrounding skin, especially redness, swelling or satellite pigmentations (small new patches of colour around a larger lesion)
- Sensation, especially itching, tingling or burning
- Consistency, especially softening or friability (small pieces breaking off easily)
- Previous history of exposure to the sun. This is the single most important risk factor.
- History of sunburns, particularly severe (blistering) sunburns in childhood.
- Ethnicity, especially with fair skin that burns rather than tans.
- Red hair or blue eyes.
- Family history of melanoma or atypical moles.
- 50 or more moles.
- Marked (extensive) freckles on the upper back.
- Previous melanoma or other skin cancer.
- Moles present at birth.
- Stay out of the sun during the midday hours (10 am to 4 pm).
- Set a good example for your children by protecting your skin.
- Wear protective clothing.
- Shade your neck and ears.
- Use sunscreen daily with an SPF of at least 30.
- Avoid sun tanning and tanning beds.
- Have your doctor check your skin at least once a year.
When to see your doctor
- If you detect any change in a mole, including its size, shape or colour, or if it becomes painful.
- If you have a bleeding mole.
- If you have a discoloured area under a fingernail or toenail (not caused by an injury).
- If you observe a general darkening of the skin unrelated to sun exposure.