Types of Skin Cancer
Three types of skin cancer account for almost 100% of the diagnosed cases. Each begins in a different cell within the skin and is named for the cell in which it begins. Divided into one of two classes, skin cancers can be non-melanoma or melanoma, with melanoma being the deadliest form.
Basal Cell Carcinoma (BCC)
The most common skin cancer in humans, BCC develops in more than one million individuals yearly in the United States, accounting for approximately 80% of all skin cancers. BCC develops in the basal cells – the cells in the lowest layer of the epidermis – and may take several forms. Some appear as shiny translucent or pearly nodules, sores that continuously heal and then re-open, pink, slightly elevated growths, reddish patches of irritated skin, or waxy scars.
Most BCC appears on skin with a history of sun exposure, such as the scalp, ears, face, and upper trunk. BCC tumors tend to grow slowly and can take years to reach a half-inch in size. While these tumors rarely metastasize (spread to other body parts), dermatologists encourage early diagnosis and treatment to prevent damage to the surrounding tissues.
Squamous Cell Carcinoma (SCC)
About 16% of skin cancers are diagnosed as SCC. This type begins in the squamous cells found in the upper layer of the epidermis. With approximately 200,000 cases diagnosed yearly, SCC tends to develop in fair-skinned, middle-aged, and older adults over long-term sun exposure. SCC most often appears as a scaly or crusted skin area with an inflamed, red base resembling a non-healing ulcer, growing tumor, or crusted skin patch.
Most commonly appearing on sun-exposed areas of the body, SCC can develop anywhere, such as the inside of the mouth and the genitalia. It may arise from actinic keratoses or dry, scaly lesions that may be reddish-brown, skin-colored, or yellowish-black. This type of cancer requires early treatment to prevent metastasis (spreading).
Accounting for about four percent of all skin cancers diagnosed, melanoma begins in the melanocyte cells located in the epidermis and gives skin its color. Coined “the most lethal form of skin cancer” because it spreads rapidly to the lymph system and internal organs, melanoma is responsible for the death of approximately one person every hour in the United States alone. Older caucasian men experience the highest mortality rate from melanoma; dermatologists believe this is because they less readily heed the early warning signs.
Early detection and proper treatment allow for a cure rate of about 95% for melanoma. Once its spreads, the prognosis is poor, so knowing the signs helps with early detection. Melanoma develops most often in a pre-existing mole. It also looks like a new mole, which is why people must know what their moles look like and be able to detect changes and spot new moles.
Other Non-Melanoma Skin Cancers
All other types of skin cancer combined account for less than 1% of diagnosed cases – they are rare and aggressive forms of skin cancer that can spread quickly to other parts of the body and require prompt and specialized treatment, such as Mohs surgery.
Classified as non-melanoma skin cancers, these include Merkel cell carcinoma (MCC) – arising in the Merkel cells located in the hair follicles and involved in sensation; dermatofibrosarcoma protuberans (DFSP) – from the connective tissue cells in the skin; angiosarcoma – arising from the blood vessels in the skin; and cutaneous T-cell lymphoma – from the lymphocytes, which are a type of white blood cell.