What is Skin Cancer?
The skin is composed of an outer layer called epidermis, which contains squamous cells, basal cells and melanocytes.
The dermis is the deeper layer of the skin and contains hair follicles, oil and sweat glands and blood vessels. Skin cancers can arise from any of these cells, each type having a characteristic clinical appearance; however, a biopsy (or sample) is usually required to confirm the diagnosis of skin cancer. Fair skinned individuals develop skin cancers far more frequently than darker skinned people; though skin cancers can also be hereditary. Excessive exposure to sun is the single most important factor associated with skin cancer of the face, eyelids and arms.
The most common type of skin cancer seen in the periocular (eye) area is basal cell carcinoma (BCC). This cancer arises from the basal cells and is also called a “rodent ulcer” as it grows very slowly.
The second most common type of skin cancer seen in the periocular area is squamous cell carcinoma (SCC). This is a more serious form of cancer than BCC, as it can spread to other parts of the body. Either may appear as a painless nodule or a sore that won’t heal. The skin may be ulcerated or there may be bleeding, crusting or distortion of the normal eyelid structure and loss of eyelashes.
Melanomas are a less common but more serious form of skin cancer, and arise from pigment-producing melanocytes. A mole that bleeds, becomes tender, changes size, shape or colour needs to be seen urgently by a physician. Sebaceous gland carcinoma is a more serious, but fortunately rare. form of skin cancer. It may appear as a recurrent chalazion, persistent eyelid inflammation, chronic red eye or thickening of the eyelid. Melanoma and sebaceous gland carcinomas can spread to other parts of the body through the bloodstream or lymphatic system, which is why prompt, aggressive treatment is necessary.