What are some differences between cutaneous carcinomas and cutaneous melanomas?

Cutaneous carcinomas (basal cell and squamous cell) are the most common type of skin cancer. They originate from non-pigmented epithelial cells within the deep layer of the epidermis. These cancers usually appear in light-skinned adults who are regularly exposed to sunlight. Cutaneous carcinomas may be flat or raised and develop from hard, dry growths that have reddish bases. This type of carcinoma is slow growing and can usually be completely cured by surgical removal or treatment with radiation.

Melanomas develop from melanocytes and range in color from brown to black and gray to blue. The outline of a malignant melanoma is irregular, rather than smooth, and is often bumpy. Unlike cutaneous carcinomas, elanoma is generally not associated with continued sun exposure. A cutaneous melanoma may arise from normal-appearing skin or from a mole. The lesion grows horizontally but may thicken and grow vertically into the skin, invading deeper tissues. If the melanoma is removed before it invades the deeper tissues, its growth may be arrested. Once it spreads vertically into deeper tissue layers, it is difficult to treat and the survival rate is very low.