Melanocytes are the cells responsible for the pigmentation in the skin. Their activity can be increased in response to inflammation. When skin becomes hyperpigmented from an injury, it is called “post inflammatory hyperpigmentation” or PIH. This is particularly prevalent in darker skin individuals, where there is more melanocytic activity, but can occur in lighter skin individuals as well.
The widely accepted scale for skin pigmentation types is the Fitzpatrick Scale. The Fitzpatrick Skin Type 1 are extremely light skinned, have blue eyes, and burn extremely rapidly with sun exposure. Type 6 individuals have very dark skin, dark eyes, and tolerate prolonged sun exposure without burning. In general, the type 4-6 skin types are the ones at risk for PIH.
PIH is possible after the following:
- Laser procedures (mainly laser resurfacing)
- Surgical incisions
- Chemical peels
- Radiofrequency (Infini is low risk)
The best way to treat PIH is prevention, if possible. Prevention consists of calming down the melanocyte metabolism. The standard recommendations are Retin A and hydroquinones. If there is a procedure a darker skin individual is planning that has risks of PIH, this regime should be started at 3 weeks prior to the procedure. It should be continued at least a month and up to 3 months afterwards. These 2 topicals are also standard therapy for patients with PIH.
Prolonged inflammation after a procedure (more than a week) in a darker skin individual, is a risk for PIH. The practitioner needs to recognize this and treat the inflammation appropriately. If there is prolonged redness of the skin, steroids and/or vascular lasers are needed to reduce this. If infection suspected, antibiotics are needed. Calming the skin is essential to prevent PIH.
The timing of PIH is very predictable. It almost always occurs about 3 weeks after a “at risk” procedure is performed.
If there is already PIH, treatments which can be used are:
- Topicals such as Retin A, hydroquinone, and steroids; Triluma contains all 3
- Chemical Peels
- Gentle laser treatments with a 1064 laser (nanosecond or picosecond)
- Possibly PRP with microneedling (experimental but minimal risk)
- Antibiotics for ongoing infections
- Laser hair removal for PIH associated with folliculitis
In general, PIH is best prevented then trying to treat after it occurs. Recognizing risk factors with certain procedures is the key to success. Treating prolonged redness is often overlooked and must be treated aggressively rather than taking a “wait and see” approach.