Skin cancer is the most common form of human cancer.There are a variety of different skin cancer symptoms. The most common warning sign of skin cancer is a change in the appearance of the skin, such as a new growth or a sore that will not heal.These include changes in the skin that do not heal, ulcering in the skin, discolored skin, and changes in existing moles, such as jagged edges to the mole and enlargement of the mole.
The following are the signs and symptoms of skin cancer which generally appear in most of the cases.

• Basal cell carcinoma usually looks like a raised, smooth, pearly bump on the sun-exposed skin of the head, neck or shoulders. Sometimes small blood vessels can be seen within the tumor. Crusting and bleeding in the center of the tumor frequently develops. It is often mistaken for a sore that does not heal. This form of skin cancer is the least deadly and with proper treatment can be completely eliminated with not so much as a single scar.

• Squamous cell carcinoma is commonly a red, scaling, thickened patch on sun-exposed skin. Ulceration and bleeding may occur. When SCC is not treated, it may develop into a large mass. Squamous cell is the second most common skin cancer. It is dangerous, but not nearly as dangerous as a melanoma.

• Most melanomas are brown to black looking lesions. Melanoma warning signs that might indicate a malignant melanoma include change in size, shape, color or elevation of a mole. Other signs are the appearance of a new mole during adulthood or new pain, itching, ulceration or bleeding.

Merkel cell carcinomas are most often rapidly growing, non-tender red, purple or skin colored bumps that are not painful or itchy. They may be mistaken for a cyst or other type of cancer.

Sun exposure - skin cancer:

A new clue comes from researchers at the University of North Carolina at Chapel Hill Schools of Medicine and Public Health. Their research indicates that early life sun exposure, from birth to 20 years old, may specifically increase the risk of melanomas with BRAF gene mutations. A different mutation, on the NRAS gene, was found in patients who had sun exposure during the later part of life (between ages 50 to 60 years old). The results indicate that different subtypes of melanoma are linked to different risk factors.

"The findings suggest that melanoma subtypes have different causes. This is important for learning more about how to prevent and treat skin cancer," said Dr. Nancy Thomas, associate professor of dermatology in the UNC School of Medicine, a member of the UNC Lineberger Comprehensive Cancer Center and lead author of the study. This finding is expected to strengthen current recommendations to protect children from sun exposure in order to prevent melanoma, Thomas said.