Are there risks from sun exposure after surgery?

Whether for cosmetic surgery, such as rhinoplasty, liposuction, hair transplantation or a cryolipolysis, for dermatological surgery, such as the excision of a mole or the removal of a cyst, or reconstructive surgery, the attentive postoperative care is essential. Among common recommendations, sun avoidance and skin protection are central.

Avoiding sun exposure after surgery is necessary for proper skin healing.

Indeed, after surgery, the skin undergoes a finely orchestrated process of wound healing, which takes place in three successive stages. The skin first enters the inflammatory phase for several days and triggers an immune response to clean the wound and prevent infection. Next, during the proliferative phase, which lasts two to four weeks, fibroblasts produce collagen and new blood vessels form, allowing the skin to rebuild gradually. Finally, the remodelling phase, which can last up to two years, consolidates the scar: collagen is organised, the area becomes more supple and pigmentation adjusts. Even though the skin surface appears to close fairly quickly, the skin remains fragile long after surgery. Skin that is not properly protected from sunlight after surgery is exposed to the following risks:

• Delayed healing: UV rays increase free radical production in the skin. Free radicals are unstable compounds that seek to react with other molecules to form an electron pair. They damage cells, DNA, and proteins. They impair fibroblasts, which synthesise granulation tissue during healing, and keratinocytes, which close the epidermis. By disrupting these cells, free radicals slow skin reconstruction.

• Hyperpigmentation: When skin is exposed to UV rays from the sun, the process of melanogenesis During which melanin is synthesized in melanocytes. However, after surgery, skin enters a remodelling phase and its barrier function is weaker than usual. Local inflammation sensitizes melanocytes to UV rays. Under sunlight, they produce excess melanin. This melanin transfers to keratinocytes, causing abnormal, persistent scar pigmentation.

• Keloid formation: Sun exposure maintains an inflammatory environment that promotes fibroblast overactivation. These cells produce type I and type III collagen in a disorganised manner. This leads to an irregular deposition of collagen fibres in the skin, resulting in raised scars that extend beyond the surgical site. This scar type is termed keloid. Besides the functional and aesthetic discomfort they cause, keloid scars can be painful and pruritic. The risk of keloids is high in individuals with darker phototypes, in whom pigmentary and inflammatory responses are more pronounced. That is why, contrary to common belief, the sun protection is equally important for darker skin.