Skin rashes are a common condition. They usually stem from something harmless, like a reaction to heat, medication, a plant like poison ivy, or a new detergent you’ve touched.
Rashes can show up on any part of your body, from your head to your feet. They can even hide in the cracks and crevices of your skin. Sometimes they itch, crust, or bleed.
Occasionally, bumps or redness on your skin can be a sign of cancer.
For example, if you notice an itchy mole on your chest that seems to be changing shape, there’s a chance you’re dealing with skin cancer.
Because cancer can be very serious — even life threatening — it’s important to know the difference between a rash caused by irritation and one caused by skin cancer.
This is why it’s important to talk with a dermatologist about any rash or growth that’s new, changing, or not going away.
While skin cancers are often asymptomatic, meaning they don’t show symptoms, they can be itchy.
For instance, basal cell skin cancer can appearTrusted Source as a raised reddish patch that itches, and melanoma can take the form of itchy dark spots or moles.
Talk with your doctor about any itchy, crusty, scabbed, or bleeding sore that’s not healing.
The most common symptomTrusted Source of skin cancer is a change in your skin, such as a:
- new growth
- sore that’s not healing
- mole that’s changing color or shape
Melanoma is a less common but more dangerous form of skin cancer because it can spread easily if not treated. One of the best ways to get a handle on its symptoms is to think of “A-B-C-D-E.”
- “A” for asymmetrical. Do you have a mole or spot that seems to be shaped oddly or have two sides that look different?
- “B” for border. Is the border of your mole or spot jagged?
- “C” for color. Is the color of your mole or spot uneven or different?
- “D” for diameter. Is your mole or spot bigger than the size of a pencil eraser?
- “E” for evolving. Have you noticed your mole or spot changing in an obvious way?
If any of these apply to a mark on your skin, it’s important to talk with a dermatologist as soon as possible.
Mycosis fungoides is the most common form of cutaneous T cell lymphoma, a type of blood cancer that involves infection-fighting white blood cells called T cells.
When these cells turn cancerous, they form a red, scaly rash on the skin. The rash can change over time, and it may:
Mycosis fungoides often shows up as an eczema-like rash in areas that typically get little sun exposure.
Actinic keratoses are crusty or scaly pink, red, or discolored bumps that appear on areas of sun-exposed skin, including the:
- backs of your arms and hands
If you have several of them together, they can resemble a rash.
They’re caused by damage from the sun’s ultraviolet (UV) radiation. If you don’t get actinic keratosis treated, it can turn into skin cancer. Treatments include:
- cryosurgery (freezing them off)
- laser surgery
- scraping off the bumps
Actinic cheilitis looks like scaly bumps and sores on your lower lip. Your lip might also be swollen and red.
It’s caused by long-term sun exposure, which is why it often affects people with lighter skin who live in sunny climates or individuals who spend a lot of time working outside.
Actinic cheilitis can turn into squamous cell cancer if you don’t have the bumps removed.
Just as the name suggests, cutaneous horns are hard growths on the skin that look like an animal’s horns. They’re made from keratin, the protein that forms skin, hair, and nails.
The horns are concerning because about half the time they grow out of precancerous or cancerous skin sores. Larger, painful horns are more likely to be cancerous.
You’ll usually just have one cutaneous horn, but they can sometimes grow in clusters.