Sun-exposed areas such as the lips and ears are especially likely to develop squamous cell carcinoma of the skin. Squamous cell carcinoma of the skin is a common form of skin cancer that develops in the squamous cells that make up the middle and outer layers of the skin. Squamous cell carcinoma of the skin is usually not life-threatening, though it can be aggressive. Untreated, squamous cell carcinoma of the skin can grow large or spread to other parts of your body, causing serious complications. Most squamous cell carcinomas of the skin result from prolonged exposure to ultraviolet (UV) radiation, either from sunlight or from tanning beds or lamps. Avoiding UV light helps reduce your risk of squamous cell carcinoma of the skin and other forms of skin cancer. Squamous cells are found in many places in your body, and squamous cell carcinoma can occur anywhere squamous cells are found. Squamous cell carcinoma of the skin refers to cancer that forms in the squamous cells found in the skin.
Squamous cell carcinoma of the skin most often occurs on sun-exposed skin, such as your scalp, the backs of your hands, your ears or your lips. But it can occur anywhere on your body, including inside your mouth, the bottoms of your feet and on your genitals. Signs and symptoms of squamous cell carcinoma of the skin include:
- A firm, red nodule
- A flat sore with a scaly crust
- A new sore or raised area on an old scar or ulcer
- A rough, scaly patch on your lip that may evolve to an open sore
- A red sore or rough patch inside your mouth
- A red, raised patch or wartlike sore on or in the anus or on your genitals
When to see a doctor
Make an appointment with your doctor if you have a sore or scab that doesn't heal in about two months or a flat patch of scaly skin that won't go away.
Where skin cancer develops
Skin cancer begins in the cells that make up the outer layer (epidermis) of your skin. One type of skin cancer called basal cell carcinoma begins in the basal cells, which make skin cells that continuously push older cells toward the surface. As new cells move upward, they become flattened squamous cells, where a skin cancer called squamous cell carcinoma can occur. Melanoma, another type of skin cancer, arises in the pigment cells (melanocytes).
Squamous cell carcinoma of the skin occurs when the flat, thin squamous cells in the middle and outer layers of your skin develop changes (mutations) in their DNA. A cell's DNA contains the instructions that tell a cell what to do. The mutations tell the squamous cells to grow out of control and to continue living when normal cells would die.
Most of the DNA mutations in skin cells are caused by ultraviolet (UV) radiation found in sunlight and in commercial tanning lamps and tanning beds. But sun exposure doesn't explain skin cancers that develop on skin not ordinarily exposed to sunlight. This indicates that other factors may contribute to your risk of skin cancer, such as having a condition that weakens your immune system.
Untreated squamous cell carcinoma of the skin can destroy nearby healthy tissue, spread to the lymph nodes or other organs, and may be fatal, although this is uncommon. The risk of aggressive squamous cell carcinoma of the skin may be increased in cases where the cancer:
- Is particularly large or deep
- Involves the mucous membranes, such as the lips
- Occurs in a person with a weakened immune system, such as someone who takes anti-rejection medications after an organ transplant or someone who has chronic leukemia
Most squamous cell carcinomas of the skin can be prevented. To protect yourself:
Wear protective clothing.
Cover your skin with dark, tightly woven clothing that covers your arms and legs, and a broad-brimmed hat, which provides more protection than does a baseball cap or visor.
Some companies also sell protective clothing. A dermatologist can recommend an appropriate brand. Don't forget sunglasses. Look for those that block both types of UV radiation — UVA and UVB rays.
Check your skin regularly and report changes to your doctor.
Examine your skin often for new skin growths or changes in existing moles, freckles, bumps and birthmarks. With the help of mirrors, check your face, neck, ears and scalp.
Examine your chest and trunk and the tops and undersides of your arms and hands.
Examine both the front and back of your legs and your feet, including the soles and the spaces between your toes. Also check your genital area and between your buttocks.