Melanoma

Skin color comes from cells called melanocytes, the ones that make pigment. Melanoma is the cancer that starts right there, in those melanocytes. But something looking dark on the skin doesn't make it a melanoma. What most people call a mole, doctors call a nevus, and a nevus isn't cancer just because it's there. Even so-called dysplastic nevi, the ones that look atypical, odd, uneven, often aren't either.

What the eye can do is raise suspicion: you notice something looks off, the way you might judge a piece of fruit by its skin and know something isn't right without being able to say what. To get from suspicion to certainty, a piece of that tissue has to be removed and examined under a microscope. Looking at the skin, no matter how trained the eye, isn't enough on its own to confirm it.