According to the Association of the American Academy of Dermatology, malignancy can occur on any part of the skin, from the scalp to the soles of the feet. Skin cancer can start under a fingernail, on the genitals, in the mouth, or on the lip.
Anyone can suspect that they have a tumor if they pay attention to:
the appearance of new moles;
strange shape of papilloma and warts;
dark spots on the skin.