Squamous cell carcinoma (SCC) is a very common type of skin cancer, typically affecting sun damaged fair skin.
The majority of SCCs develop in solar keratoses. These are common small scaly lesions arising on the face, ears and hands of white skinned people who have spent many years outdoors. A thickened or tender keratosis may be a SCC. They may also develop in old burn scars and ulcers.
SCCs vary in size from a few millimetres to several centimetres in diameter. Sometimes they grow to the size of a pea or larger in a few weeks, though more commonly they grow slowly over months or years. They may be tender. Some SCCs appear as sores that fail to heal. A common site is the bottom lip; if a sore has not gone in 3 weeks, see your doctor. SCCs are often crusty and may bleed easily.
Luckily, SCC is not usually a threat to life as secondary spread (metastasis) is uncommon. SCC on the lip or ear can be dangerous however.
Bowen’s disease is an in situ SCC. This means the malignant cells are confined to the epidermis, the outside layer of the skin. Bowen’s disease can precede invasive SCC in which the malignant cells have penetrated into the dermis, the deeper layer. Bowen’s is a flat red scaly patch up to several centimetres wide, often found in large numbers on the lower legs. Most often due to sun exposure, they can also arise as a consequence of arsenic ingestion many years earlier. The development of a lump or bleeding in Bowen’s disease may indicate progression into invasive SCC.
Keratoacanthoma is an alarming type of SCC because it grows very quickly. It can develop into a dome-shaped nodule 2 or 3 centimetres in diameter over a few weeks! They are rarely dangerous and can even drop off by themselves. Surgical removal is usually recommended, as we cannot predict which ones will fall off.
Most SCCs remain localised but they can occasionally spread to other sites of the body. These secondary growths are known as metastases. Metastases usually develop in the nearest lymph glands, and are most likely if the original SCC is on the lip or ear. Secondary growths are more difficult to treat than the original skin lesion, as surgery may not always remove them completely.
- Early detection means easier treatment, and less scarring.
- Make sure you protect your skin from the sun at all times.
- Arrange for a complete skin examination from time to time.
- Ask your dermatologist or GP to check any persisting or growing lumps or sores.