The skin cancers which are most commonly diagnosed in a dermatology clinic are basal cell carcinoma and squamous cell carcinoma (non-melanoma skin cancers) and melanoma. The top layer of the skin is called the epidermis. This epidermis contains basal cells, squamous cells and melanocytes. The types of skin cancer are defined by the cells from which they are derived.
Non-melanoma skin cancers are the most common cancers. They refer to skin cancers that are not melanoma. The two most frequently diagnosed skin cancers are basal cell carcinomas and squamous cell carcinomas.
Basal cell carcinoma
Basal cell carcinomas are derived from basal cells in the bottom layer of the epidermis. They are slow growing and it is extremely rare for them to spread to other parts of the body. However, they can grow and cause local destruction.
They most commonly occur on sun-exposed sites. There are many different types but the most common type presents as a shiny smooth spot which gradually enlarges and ulcerates (a non-healing part) in the centre. These often present as bleeding non-healing lesions.
Squamous cell carcinoma
Squamous cell carcinomas are derived from squamous cells of the epidermis. They also occur in sun-exposed areas but can occur in non-exposed areas and in sites that have been subject to trauma or inflammation over a long period of time e.g. a chronic ulcer.
The typical squamous cell carcinoma is a small lump in the skin which often has a crust overlying it and can ulcerate. They are sometimes painful and can rapidly grow. This type of skin cancer can spread so it is important to identify them early.
Melanoma is derived from melanocytes which are cells that produce melanin, or pigment-producing cells, in the bottom layer of the epidermis. Melanoma is a dangerous form of skin cancer which has the potential to spread to other parts of the body if it is not treated early. The best chance of cure is by surgical excision at the earliest stage possible.
Melanoma can occur in a pre-existing mole or can occur as a new spot, freckle or mole. Something on your skin that is changing should be reported to your doctor. A shape in colour or shape can be important however it is important to remember that while most moles are darkly pigmented, they can also occur with no pigment so be vigilant for pink, red or skin-coloured lesions that are new, changing or not going away. Melanomas can occur anywhere on the body, not just on sun-exposed areas.
There are many other types of cancers which can affect the skin. These include such tumours as merkel cell carcinoma, atypical fibroxanthoma, primary adenocarcinomas, sebaceous gland carcinoma and pilomatrix carcinomas.
For new, changing or non-healing lesions
Contact a dermatologist if you are concerned about a skin lesion
A comprehensive examination of your skin
A magnifying lens is used to evaluate specific lesions
Skin examination under the microscope if deemed necessary
