Melanoma is the least common but the most deadly type of skin cancer. Melanoma symptoms include a change in the shape, size, or color of a mole, but melanomas can also look like a bruise that doesn't heal or a dark streak under a finger or toenail.

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This Influencer’s Birthmark Turned Out to Be Melanoma: 'I Could Feel It Growing'

Jenna Colgrove, 33, noticed the birthmark near her ankle looked strange. Weeks later, she was diagnosed with melanoma, the deadliest form of skin cancer.

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Is It a Mole...or Skin Cancer?

Find out the differences between regular moles and ones that could be potentially cancerous.