While basal cell and squamous cell carcinomas tend to confine themselves to your hide, melanoma—which is typically characterized by a new or changing mole—is deadly because it eventually spreads into your body and causes systemic disease, Dr. Friedman explained.
If a melanoma does metastasize, the types of symptoms you experience depend a lot on the location of your cancer. “If the melanoma is by your lungs, you could have shortness of breath, or if it’s on your head, you may have headaches or vision trouble,” he says. “Really, the symptoms are all over the place.”
Unfortunately, if you don’t catch a melanoma until it reaches this stage, the prognosis is grim. “I hate to be dire, but if you’re experiencing these symptoms because a melanoma has metastasized, you’re already in big trouble,” Dr. Friedman said.
There’s also no predicting where a melanoma mole is likely to show up or take root, because “there’s really no predictable pattern,” he added.
That’s why it’s so important to pay attention to your skin by doing a self-exam at least once per month: Flagging any odd changes to your doctor ASAP can save your life.