Imagine this: A woman (we’ll call her Sara) treats herself to a manicure and a pedicure. As she walks out of the nail salon, she gets a call from her dermatologist’s office, reminding her that she has an appointment the next day. Annoyed, Sara decides she isn’t going to ruin her mani-pedi for a checkup. Sara, however, could be making a dangerous mistake.

“Make sure you remove all nail polish from fingers and toes,” Dr. Glodny told Health Digest. “While less common, skin cancers can develop beneath your nail. If you are wearing nail polish, it may hide any signs of skin cancer.” In fact, the deadliest of all skin cancers, melanoma, can occur under and/or around the nails on the fingers and the toes (via AAD). Warning signs of melanoma include nails lifting away and separating from the nail bed, nails splitting down the middle, bumps under the nails, the skin around the nails becoming darker, and a dark streak on the nails themselves.

While it’s good to recognize possible signs of skin cancer, it’s also important not to self-diagnose. Instead, note any changes, and as the AAD recommends, have a board-certified dermatologist examine you and address your concerns. Most importantly, if you do see possible red flags of skin cancer, especially melanoma, don’t delay making an appointment with your dermatologist.