Erythema above the lips, making it more difficult to distinguish the vermilion border.
This left cheek incision extends from the left commissure towards the left ear and it breaches the vermilion border (click to see close-up). In order to maintain aesthetics as best possible, the first suture was placed at or near the vermilion border to ensure a contiguous line upon healing.
The vermilion border is the normally sharp demarcation between the lip (red colored) and the adjacent normal skin. 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 hair.
There are two reasons for the border being red:
The epithelium is thin.
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.