What causes skin tags is unknown,but they do appear more frequently in areas where the skin is rubbed by clothing or by other body parts, such as in creases like your under arm.They also tend to appear in hot, moist places such as under the breasts, between the thighs, or around the genitals.Please tell me I don't have to get these things checked for cancer like I do with my moles.I have good news and bad news.Give me the good news.Skin tags are never cancerous.That is good news. But then, I can't imagine what the bad news is.Because people so often confuse moles for skin tags, you should monitor them just as you do your moles.If you notice changes or anything that would be suspicious in a mole, you should have your doctor check it.