Melanoma is the deadliest type of skin cancer, according to Mayo Clinic. It forms in the melanocytes, which are structures that contain melanin, a substance that gives skin and eyes their color. Melanoma does not only form in the skin; it also forms in the eyes and internal organs. Fortunately, this is rare.
Melanoma often begins as a mole that does not look quite normal, explains the American Academy of Dermatology. It is asymmetrical, which means if it is cut in half, the halves are not the same size or shape. It has an irregular border and often has more than one color. A single mole can be shades of brown, black, blue, red or white. It is often unusually large. A person should be suspicious if the mole is larger than a pencil eraser and/or changes over time.
Besides these signifiers, melanoma might not cause symptoms, states the American Academy of Dermatology. But it may also be painful, bleed or itch. Melanoma may also present as a bruise that refuses to heal or a black area beneath a nail.
Melanoma in its early stage can often be removed with surgery, according to the American Cancer Society. If the cancer is advanced, it might also need to be treated with chemotherapy, radiation, immunotherapy or targeted therapy.