The vermilion border, also called margin or zone, is the normally sharp demarcation between the lip and the adjacent normal skin. It is where lipstick is sometimes applied. It represents the change in the epidermis from highly keratinized external skin to less keratinized internal skin. It has no sebaceous glands, sweat glands, or facial hair. It has a prominence on the face, creating a focus for cosmetics and is also a location for several skin diseases. Its functional properties, however, remain unknown.
Structure
The lips are composed wholly of soft tissue. The skin of the face is thicker than the skin overlying the lips where blood vessels are closer to the surface. As a consequence, the margin of the lips shows a transition between the thicker and thinner skin, represented by the vermilion border. It therefore has the appearance of a sharp line between the coloured edge of the lip and adjoining skin. It has been described as a pale, white rolled border and also as being a red line. This fine line of pale skin accentuates the colour difference between the vermilion and normal skin. Along the upper lip, two adjacent elevations of the vermilion border form the Cupid's bow.
Microanatomy
The vermilion border represents the change in the epidermis from highly keratinized external skin to less keratinized internal skin. It has no sebaceous glands, sweat glands, or facial hair. There are two reasons that the border appears red in some people:
The epithelium is thin and therefore the blood vessels are closer to the surface.
This epithelium contains eleidin which is transparent and the blood vessels are near the surface of the papillary layer, revealing the "red blood cell" color. At the angles of the mouth, there are sebaceous glands, without hair follicles, which are called Fordyce's spots.
Infections may involve the vermilion border. Cold sores are one common infection. Impetigo is another.
Skin cancer can also occur at the vermilion border.
Cosmetic appearance
Lips that have good volume can be highlighted by defining them and injecting a dermal fillerinto the white vermilion border.
Sunlight exposure can blur the junction between the vermilion border and the skin. Applying lip balm and sunscreen moisturizes protects it from sunlight.
Surgery
A vermilionectomy is the surgical removal of the vermilion border. It is sometimes performed to treat carcinoma of the lip. Close attention is given when repairing any injury to the vermilion border. Even 1 mm of vermilion misalignment could be noticeable.
