2. Moles or melanoma
A concern about nail color is one of the most common complaints dermatologists hear, Dr. Poblete-Lopez says. Discolorations usually appear in lines that run from cuticle to tip, and they can be benign moles or cancerous melanomas. African-Americans and Asians are more likely to experience regular pigmentation changes that are related to ethnicity.
You should consult a dermatologist if the skin under the nail plate — the hard part of the nail, covering the fingertips — develops any brown coloring, she says. These developments are always more of a concern if they affect a single finger instead of all. Brown lines that run into the cuticle could be a sign of melanoma. Ones that stop at or before the cuticle are likely caused by moles.