Skin: Histology and Physiology of Wound Healing

It is important to understand the histology and physiology of skin for the prediction and optimization of wound healing. Optimal postoperative wound healing to minimize scarring entails minimizing local, systemic, and environmental factors that lead to poor wound healing. Keeping the wound clean and moist, minimizing trauma, and infection are the local wound tenets. Systemic tenets include minimizing medications that inhibit processes of wound healing, maintaining adequate nutrition, pain palliation, UV protection, and smoking cessation. This article presents the dynamic process of wound healing and the basic tenets to minimize scarring.

1.

Skin is composed of several layers that are essential to its function and response to injury: the epidermis, dermis, and hypodermis. Healing is a dynamic progression encompassing hemostasis, inflammation, proliferation, and remodeling
2.

Pilosebaceous units are the source of all epithelial stem cells essential for reepithelialization and wound healing
3.

Multiple extrinsic and intrinsic factors affect healing, specifically the effect of immune system modulation (medications and diseased states)
4.

It is most optimal to wait at least 4–6 weeks after smoking cessation for elective surgical interventions
5.

Keloids and hypertrophic scarring are a result of overabundant collagen production, and decrease collagen breakdown. Keloids are difficult to treat, due to their recurrent nature. It is important to identify individuals prone to keloid formation for surgical planning purposes

Key Points

Self-Test Questions
The following questions are intended for the reader to self-test. The answers, with full background, are covered within this article. The correct answers are provided at the conclusion of the article.
1.

A 19-year-old woman is on isotretinoin (Accutane) for acne and has a facial acne scar that she wishes to be dermabraded. What do you counsel the patient about?
- a.
  
  She needs to be off the medication for 1 year to limit the risk of scarring
- b.
  
  She should continue the medication because the extra vitamin A will improve her healing
- c.
  
  You cannot resurface her acne scar because of the long-lasting effects of this medication
- d.
  
  Encourage 2 g of vitamin C daily for 2 weeks before the procedure
2.

A 73-year-old insulin-dependent diabetic man with a serum glucose level of 300 mmol/L comes to your office for a rhytidectomy. How do you optimize your results?
- a.
  
  Refer to endocrinologist for tight diabetic control before surgery
- b.
  
  Decline the surgery because the risk of failure is increased
- c.
  
  Start the patient on vitamin E supplementation 2000 IE daily 2 weeks before surgery
- d.
  
  Double his insulin dose on the morning of his surgery
3.

A 30-year-old man has a partial-thickness 4 × 4-cm abrasion on his right cheek. What should be the best treatment?
- a.
  
  Place a split-thickness skin graft
- b.
  
  Place a full-thickness skin graft
- c.
  
  Keep the wound bed moist with a moisture retentive ointment
- d.
  
  Keep the wound dry to maximize reepithelialization.
4.

A 50-year-old man sees you about a large wide scar on his neck. On inquiring, the patient states he had a lymph node removed last year and this scar has grown bigger than the cyst was. What do you counsel him about?
- a.
  
  That he most likely has a hypertrophic scar and that the likelihood is that this will not happen on further surgical procedures
- b.
  
  That this is a keloid and that with vitamin E ointments it should resolve
- c.
  
  That this is a hypertrophic scar that will completely go away with simple excision
- d.
  
  That this is a keloid and that multiple procedures along with steroid injections may be required to excise it, but still there is no guarantee it will be removed completely.