Melanoma is the least common but most serious type of skin cancer.
It usually appears as an abnormal or new or changing mole. It can appear anywhere on the body, but most often on the back, legs, arms and face. Most melanomas have an irregular shape and more than one colour.
In the UK around 11,100 cases of melanoma each year are linked to excessive exposure to sunlight and use of sunbeds.
Melanoma can be fatal if found late but is easily treated if found early.
Squamous cell carcinoma
Squamous Cell Carcinoma (SCC) or Bowen's disease accounts for 20% of skin cancers and is usually easily treated.
The main sign is a red, scaly patch on the skin that is 1-3 cm in diameter and which may or may not be itchy. The affected skin can be red and sore and may bleed and scab.
Bowen's disease can appear anywhere on the skin, especially the trunk, arms or legs.
It's important to get a proper diagnosis, as SCC or Bowen's disease can look like benign conditions such as psoriasis or eczema.
Basal cell carcinoma
Basal Cell Carcinoma (BCC) accounts for 75% of skin cancers and is also easily treated.
It usually appears as a red or pink lump, although it can be pearly-white or 'waxy' looking and may contain visible blood vessels. The discoloured patch of skin is flat and scaly and can have either a flesh-coloured or brown appearance.
BCCs can develop anywhere on the body, but usually appear on parts of the body that have been exposed to the sun. Lumps usually develop on the face, ears and neck, while the discoloured skin patches usually develop on the chest and back.
Actinic keratosis (a pre-cancerous skin lesion)
Actinic keratoses, also known as solar keratoses, are dry scaly patches of skin caused by damage from many years of sun exposure. Actinic keratoses only tend to be seen in people over the age of 40.
The patches are usually harmless but can develop into Squamous Cell Carcinoma.
They are pink, red or brown in colour and range in width from 0.5 to 3cm. Sometimes the skin can become very thick over them and occasionally they can look like horns or spikes.
They are most commonly found on the face, neck, forearms and backs of hands (in men) on the rims of the ears and bald scalps (in women) on the legs below the knees.
Actinic keratoses are most commonly seen in fair-skinned people, especially those with blue eyes, red hair, freckles and a tendency to burn in the sun. People who have lived or worked abroad in a sunny place or who have worked outdoors or enjoy outdoor hobbies are most at risk.