Why a Cut on Your Face Heals Differently From One on Your Back
Skin is not one organ with one set of rules. Its thickness, blood supply, tension, oil production and healing behaviour vary enormously from one part of the body to another, and a surgeon planning an excision is thinking about all of it. This is why the same operation leaves a nearly invisible line on an eyelid and a thick raised scar on a shoulder, and why nobody can promise you a particular scar in advance.
Skin is not one organ following one set of rules. How thick it is, how much blood reaches it, how tightly it is stretched, how oily it is and how it heals all vary enormously from one part of the body to another, and a surgeon planning to cut something out is thinking about every one of those. It is why the same operation leaves a nearly invisible line on an eyelid and a thick raised scar on a shoulder, and why nobody can promise you a particular scar in advance.
Why a Cut on Your Face Heals Differently From One on Your Back: the essentials
The short version
The eyelid, at a fraction of a millimetre
Your eyelid, which is a fraction of a millimetre thick.
The palms and soles, with a greatly thickened outer layer
Your palms and the soles of your feet.
The face and scalp, which is why they heal fast and bleed freely
Your face and scalp, which is why they heal fast and also bleed freely.
A wound pulled apart by movement heals wider
A wound that gets pulled apart every time you move heals wider.
Where the wound is affects the technique, the closure and the realistic result
Where the wound is changes the technique, the way it is closed, and what result is realistic.
Chest, shoulders, upper back and earlobes
Chest, shoulders, upper back and earlobes.
Thickness, supply and speed
Thickness, blood supply and speed
Eyelid skin is among the thinnest on the body, with very little fat beneath it and an exceptional blood supply. Skin on the back is several times thicker, under considerably more tension, and less generously supplied. Those two facts predict most of the difference in how they behave when cut.
Eyelid skin is among the thinnest anywhere on you, with almost no fat underneath it and an unusually good blood supply. Skin on your back is several times thicker, under far more stretch, and less well supplied with blood. Those two facts predict most of the difference in how the two behave when they are cut.
A generous blood supply means faster delivery of the cells and signals that close a wound, which is why facial wounds heal quickly and why facial infections are comparatively less common. It also means facial procedures bleed more, which is a nuisance during the procedure and a reason for the pressure dressing afterwards.
A good blood supply means the cells and signals that close a wound arrive faster, which is why wounds on the face heal quickly and why infections there are relatively less common. It also means procedures on the face bleed more, which is a nuisance at the time and the reason for the pressure dressing afterwards.
Thin skin also has less to make a scar with. There is simply less dermis to lay down disorganised collagen, which is part of why fine facial closures can end up as a line you have to be told about to find.
Thin skin also has less to build a scar out of. There is simply less tissue there to lay down messy new fibres, which is part of why a careful closure on the face can end up as a line you have to be shown before you can find it.
Tension is the quiet variable
Stretch is the quiet one
Skin is under tension, and that tension runs in consistent directions that vary by body site. A wound that lies along the direction of tension is held closed by the skin itself. A wound that crosses it is pulled open every time the area moves, and a wound that is repeatedly pulled open heals wider and thicker.
Your skin is under tension, and that tension runs in particular directions that change depending on where you are on the body. A cut that runs along the direction of the tension is held shut by the skin itself. A cut that runs across it gets pulled open every time you move, and a wound that keeps being pulled open heals wider and thicker.
This is why a surgeon plans the direction of an excision rather than simply cutting around the lesion, and why an ellipse is often longer than people expect. The extra length is what allows the wound to close along the favourable line without a bunched end. It is also why scar revision is sometimes about reorienting a scar rather than removing it.
This is why a surgeon plans which way to cut rather than simply cutting a circle around the spot, and why the resulting oval is often longer than people expect. That extra length is what lets the wound close along the favourable line without bunching up at the ends. It is also why fixing a scar is sometimes about changing its direction rather than removing it.
Areas of high, constantly changing tension are the difficult ones: the chest, the shoulders, the upper back, and anywhere over a joint. They are also, not coincidentally, where hypertrophic scars and keloids are most likely.
The difficult areas are the ones under high, constantly changing tension: the chest, the shoulders, the upper back, and anywhere over a joint. Not coincidentally, those are also where thick raised scars are most likely.
Why some sites scar badly
Why some places scar badly
A scar is the body choosing speed over perfection. Rather than reconstructing the original architecture, it lays down collagen quickly and in bulk, then spends months remodelling it. Whether the result is a fine line or a raised ridge depends on how much collagen is laid down, how long the inflammatory phase runs, and how much the wound is being pulled.
A scar is your body choosing speed over perfection. Rather than rebuilding the original structure properly, it lays down new fibres fast and in bulk, and then spends months tidying them up. Whether you end up with a fine line or a raised ridge depends on how much was laid down, how long the inflammation ran for, and how much the wound was being pulled.
Keloids go further, growing beyond the boundary of the original wound, and they have a strong site preference and a familial and ethnic pattern. Earlobes, chest and shoulders are the classic sites. Anyone with a history of keloid formation should say so before any procedure, including cosmetic ones, because it changes the risk conversation entirely.
Keloid scars go further still, growing out beyond the edges of the original wound. They have favourite places on the body and they run in families and in particular ethnic groups. Earlobes, chest and shoulders are the classic sites. If you have ever had one, say so before any procedure at all, including cosmetic ones, because it changes the risk conversation completely.
Time matters too. A scar is not finished when it looks finished. Remodelling continues for many months, and a scar that is red and firm at six weeks is often considerably better at a year without anything being done to it. This is why good practice is to wait before judging, and to be sceptical of any intervention offered urgently on a young scar.
Time matters too. A scar is not finished when it looks finished. It keeps reorganising for many months, and a scar that is red and firm at six weeks is often much better at a year with nothing done to it at all. That is why good practice is to wait before judging it, and to be wary of anyone urgently offering to treat a young scar.
What it means for a procedure
What this means for your procedure
It means the site is part of the decision, not just the diagnosis. The same lesion in two places can warrant different techniques, different closures and a different conversation about the likely result.
It means where the spot is forms part of the decision, not just what the spot is. The same lesion in two different places can call for different techniques, a different way of closing it, and a different conversation about the likely result.
For a patient the useful questions are specific: what will the scar look like, which direction will it run, how long before I can judge it, and what should I do if it starts to thicken. A clinician who answers those precisely is planning; one who answers only that it will be fine is not.
The useful questions to ask are specific ones. What will the scar look like? Which direction will it run? How long before I can judge it? And what should I do if it starts to thicken? A clinician who answers those precisely is planning. One who only says it will be fine is not.
It also means the aftercare instructions are not a formality. Protecting the wound from tension, from the sun and from infection during the weeks when collagen is being laid down has more effect on the final appearance than almost anything done later.
It also means the aftercare instructions are not a formality. Keeping the wound out of tension, out of the sun and free of infection during the weeks when the new fibres are being laid down affects the final look more than almost anything anyone does later.
Questions patients ask
Why did my last scar heal well and this one badly?
Why did my last scar heal well and this one badly?
Most often because the sites differ. Tension, thickness, blood supply and movement vary widely across the body, and a person who scars finely on the face may scar thickly on the chest or shoulder.
Most often because they are in different places. Tension, thickness, blood supply and movement vary a lot across the body, and someone who scars beautifully on the face can scar thickly on the chest or shoulder.
How long before I know what a scar will look like?
How long before I know what a scar will look like?
Scars remodel for many months. A reasonable first assessment is at three months, but meaningful judgement is usually at a year, and many scars improve considerably in that period without intervention.
Scars keep changing for many months. A first look at three months is reasonable, but any real judgement usually waits until a year, and many scars improve a great deal in that time on their own.
Does sun affect a healing scar?
Does sun affect a healing scar?
Yes. Ultraviolet exposure on a new scar can cause lasting darkening, and it is one of the few things a patient can straightforwardly control. Covering or protecting a new scar for its first months is worth the effort.
Yes. Sun on a new scar can darken it permanently, and it is one of the few things you can straightforwardly control yourself. Covering or protecting a new scar for its first few months is worth the trouble.
Should I use silicone on a scar?
Should I use silicone on a scar?
Silicone sheets and gels have reasonable evidence for improving raised scars and for preventing thickening in people at risk. They require consistent use over months, which is the usual reason they fail.
Silicone sheets and gels have reasonable evidence behind them for improving raised scars and for preventing thickening in people who are prone to it. They have to be used consistently for months, and not doing that is the usual reason they fail.
I get keloids. Can I still have a cosmetic procedure?
I get keloid scars. Can I still have a cosmetic procedure?
It depends on the procedure and the site, and it changes the risk calculation substantially. Tell the clinician before anything is planned; there are sites and techniques that are reasonable and others that are not worth the risk.
It depends on the procedure and on where it is, and it changes the risk a great deal. Tell the clinician before anything is planned. There are places and techniques that are reasonable, and others that are simply not worth the risk.
Talk it through with a physician first.
Every plan starts with an assessment of your skin, your anatomy and what you actually want to change.
This page is general health information, not medical advice. It cannot tell you whether a treatment is right for you. Approved uses, risks and results differ from person to person, and product labelling changes. Ask us at Dermatology and Laser Centre about your own situation, or make an appointment, and seek urgent care for any serious symptom.
