Skin cancer is a condition that occurs when genetic mutations cause skin cells to grow abnormally. In the majority of cases, exposure to ultraviolet light induces these genetic mutations; however, a weakened immune system, exposure to toxins and increasing age also increase an individual's risk for developing skin cancer, according to the Mayo Clinic. There are three main types of skin cancer, each varying in the degree to which they invade deeper layers of skin and other tissues within the body.
Basal Cell Carcinoma
Basal cell carcinoma is the most common type of skin cancer worldwide, according to the American Academy of Dermatology. Though it rarely spreads throughout the body, it can invade and destroy surrounding skin tissue; therefore, prompt biopsy and removal of basal cell tumors is important to prevent superficial disfigurement. According to the Mayo Clinic, basal cell cancers usually develop on areas of skin that are exposed to the sun. They commonly appear as flat, scaly patches of discoloration on the skin of the chest or back. Other times, they form raised bumps that can bleed and crust over. The most serious and invasive form called morpheaform basal cell carcinoma appears as a smooth scar that is white and waxy in appearance.
Squamous Cell Carcinoma
Squamous cell carcinoma--the second most common type of skin cancer--usually develops as a result of prolonged exposure to ultra-violet radiation from the sun or tanning lamps. Yet, these cancers can develop on parts of the skin that are not exposed to the sun, including the inside of the mouth, genitals and anus, in turn making them difficult to detect. According to the Mayo Clinic, most people develop red nodules, or flat, scaly lesions on the ear, neck, lips, face, hands or arms. Ulcerated sores may develop on top of existing scars or in mucous membranes of the mouth and genitals. If caught early, squamous cell cancers are curable; however, they can invade surrounding tissue and become disfiguring if left untreated.
Melanoma
A melanoma is a malignant, or cancerous, skin tumor originating in the melanocytes--the pigment-producing cells found in the skin, eyes and hair. Melanomas are the most serious type of skin cancer as they may spread to the lymph nodes and vital organs, leading to severe illness or death. The presence of atypically-shaped brown or black moles on the skin can be a warning sign for melanoma, and, according to the Skin Cancer Foundation, individuals with more than 100 moles are at heightened risk of developing melanoma. Melanomas are classified into one of four categories depending upon how far they have penetrated the skin and/or spread throughout the body. The most common type of melanoma--especially among young people--is called a superficial spreading melanoma. These melanomas spread laterally across the skin for some time before penetrating vertically down into deeper tissue. Lentigo maligna--a melanoma commonly seen in the elderly and those living in Hawaii--usually forms on skin that has been damaged from chronic sun exposure. Like a superficial spreading melanoma, lentigo maligna spreads laterally as a mottled brown or black mole before invading deeper tissue. The third category of melanomas, known as acral lentiginous melanoma, is distinct in that it typically originates on the skin of the soles of the feet, palms of the hands or beneath the nails. Finally, a nodular melanoma appears as a bump on the skin, and, by the time of diagnosis, it has already invaded deep tissue. The raised mole may be black, blue, white, gray, red or skin-colored.
