Skin Cancer Information
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What Is Skin Cancer?
The most common cancer in the United States, skin cancer develops in the tissues of the body’s largest organ: the skin.
Understanding Skin Cancer
Skin cancers usually develop in the epidermis, the top layer of skin. The cancer may initially appear as a bump, nodule or irregular patch on the surface of the skin. As the cancer grows, the size or shape of the visible skin mass may change. As these visible changes are occurring, below the surface of the skin, the cancer is likely expanding and moving into the lower layers of the skin. The cancer will continue to grow down into the dermis and the subcutaneous tissues, and in the most advanced stages, the cancer may spread into nearby muscle tissue, cartilage or bone. Once the cancer spreads into the blood or lymph fluids, it may reach other areas in the body, like the liver or lungs.
Types of Skin Cancer
There are several different types of skin cancer:
- Melanoma develops within specialized cells called melanocytes that produce the skin pigment, melanin. A collection of melanocytes may form a mole, a type of benign (non-cancerous) growth. Most moles never develop into cancer, but a mole that begins to change in size, shape or color may be a sign of melanoma.
Non-Melanoma Skin Cancers (keratinocyte cancers):
- Basal cell carcinoma develops within the basal cell layer of the skin; the lowest part of the epidermis. This type of cancer tends to occur in areas of the skin that receive the most exposure to the sun, like the head and neck. Basal cell carcinomas are slow growing and are therefore usually easy to remove if found early on. Nearly 80 percent of skin cancers are classified as basal cell carcinomas.
- Squamous cell carcinoma is the second most common type of skin cancer, accounting for approximately 20 percent of skin cancers. Squamous cells are found in the epidermis, usually above the basal cell layer.
- Keratoacanthomas are usually a benign (non-cancerous) epidermal tumor. These tumors usually grow slowly and they often go away on their own. Keratoacanthomas tumors that do continue to grow are often treated like as a form of squamous cell carcinoma.
Other very rare forms that make up less than 1 percent of skin cancers include: kaposi sarcoma, merkel cell carcinoma, cutaneous (skin) lymphoma, skin adnexal tumors and various types of sarcomas.
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