The formation of skin pigmentation
In normal skin, melanocytes convert tyrosine into melanin via the enzyme tyrosinase. This process occurs within specialized intracellular vesicles called melanosomes, which are then transferred to keratinocytes and sent to the epidermal surface.
The quantity, melanin content, and distribution of these melanosomes determine the various hues of human skin color . Pigmentation is necessary to give our skin color but the problem begins when the skin is over or under producing pigmentation!
What is hyperpigmentation?
Hyperpigmentation is a broad term that refers to a skin condition in which the skin is discolored or darkened, it can be the result from an increase in melanin production, and less commonly, from an increase in the number of active melanocytes.
Epidermal hyperpigmentation: results from increased melanin production and/or melanosome transfer to keratinocytes. This melanin will be shed with the monthly turnover of the epidermis.
Dermal hyperpigmentation: develops when melanin crosses the damaged basement membrane, where it is retained by dermal macrophages, sometimes permanently . The deeper the pigment, the tougher it is to treat.
Several methods of treatment are available depending on the condition, and a thorough understanding of the molecular mechanisms involved in pigmentation is essential for selecting the best treatment options; treatments involve photoprotection and using topical products and in-office procedures that act via different mechanisms in the melanin pathway to prevent new spots and lighten the existing spots.
Some of the treatments act by inhibiting tyrosinase enzyme so stoping melanin formation (Hydroquinone, Ascorbic acid) others act by blocking melanin transfer (Niacinamide).
Next chart shows some of the available treatments for hyperpigmentation and the mechanism they use.
Types of Hyperpigmentation
1. Post-Inflammatory Hyperpigmentation
Post-inflammatory hyperpigmentation refers to the darkening of skin that occurs after an inflammatory eruption such or skin injury. Post-inflammatory changes can occur both in the epidermis and dermis.
Caused by: acne, skin injury.
Treatments: skin‐lightening agents, chemical peels, lasers and definitely photoprotection to prevent the worsening of PIH.
2. Periorbital hyperpigmentation
Also referred to as dark circles is characterized by bilateral darkening of the orbital skin and eyelid and is more frequently observed in the skin of color.
Caused by: genetic or constitutional pigmentation, dermal melanocytosis, PIH secondary associated with contact dermatitis, shadowing due to skin laxity and tear trough associated with aging, Excessive sun exposure, hormonal causes.
Treatments: Skin‐lightening creams, chemical peels, intense pulsed light (IPL), Q‐switched ruby laser, autologous fat transplantation, combinations of fat grafting and blepharoplasties as well as fillers have all been tried, but none have provided long‐term satisfactory treatment.
Melasma is a common acquired symmetrical blotchy hyperpigmentation of sun-exposed areas on the face (cheeks and upper lips) and neck found predominantly in women who who are pregnant or taking oral contraceptives. In the epidermal type, the pigment is brown and margins are geographical and more well‐defined, whereas, in the dermal type, pigment is of a more grey‐brown quality and margins are poorly defined.
Caused by: genetic predisposition, ultraviolet light exposure, and hormonal influences (my mom developed melasma on her cheek when she started injecting Insulin).
*There are 2 factors that can contribute to the spreading of melasma: visible light and heat.
Treatments: Melasma is difficult to treat. Like traditional hyperpigmentation, a combination of sunscreen, topical lightening agents, chemical peels (epidermal melanin responds best) and laser therapy might work; however, chemical peels and laser treatments for Melasma carry the risk of Post Inflammatory Hyperpigmentation.
Patients with resistant melasma, especially with a prominent dermal component that is often very hard to treat have been successfully treated with local or full‐face dermabrasion up to the upper or mid‐dermis.
One of the well-studied combination of lightening ingredients which can give excellent results is this prescribed formulation:
Hydroquinone + Tretinoin + Steroid
The theory behind the effectiveness of this combination is that tretinoin prevents the oxidation of hydroquinone and improves epidermal penetration while the topical steroid reduces irritation from the other two ingredients and also decreases cellular metabolism, which inhibits melanin synthesis.
Various versions of this formula with different concentrations of ingredients have been studied, I personally have used this combo year ago for about 4 months to combat acne, bumpy skin and Post inflammatory hyperpigmentation and the results I got were amazing! However there are some side effects associated with this product! Tretinoin is a very powerful retinoid so after two months of usage my skin became super thin, and because of steroid you might grow facial hair!!! In addition, using Hydroquinone for extended periods of time is frowned upon and not recommended. According to Dr. Hadley King because of steroids, it is recommended to use Tri-Luma only for 2 months at a time.