A nasal pleat, also known as a transverse nasal pleat, nasal crease, or nasal groove, is a lightly discolored horizontal line that crosses the bridge of the nose just above the cartilaginous tip, where it joins the nasal bone.
This crease is most often a symptom of the 'allergic salute', a habitual, chronic, and automatic wiping of the nose due to chronic allergies, sinus infections, and adenoid hypertrophy. It is one of the classic aspects of adenoid facies.
Nasal creases are most common in children, although they may certainly appear in adulthood. In black and other dark-skinned populations nasal creases may be more prominent, as it will often show up as a quite light-colored line. A nasal crease is not a concern in-of-itself, but a chronic runny nose is a symptom of something wrong, and if the underlying cause has not been previously identified, you should probably check in with your doctor before things become worse.