All the structures influencing dermal pigmentation are vastly confined to the skin layers. That is why it is crucial to understand the skin structure in order to grasp the mechanism of pigmentation, and how deep it is under your skin layers.
In general terms, the skin is divided into three macroscopic layers:
- Outermost Epidermis
- Subcutaneous Fat
The epidermis, on the other hand, comprises five subdivisions, going respectively from the deepest to the most superficial one:
- Basal Cell Layer
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum (only in the thicker skin like on the soles of the feet)
- Stratum Corneum
The subjacent dermis contains multiple structures essential for the skin’s nutrition like blood vessels as well as the so-called skin appendages embracing, among other things, sweat and sebaceous glands.
Shifting the focus to skin pigmentation, one should mostly concentrate on the layers of the epidermis. It is the site where the skin’s pigment, or melanin, is produced and stored.
In the basal layer, one can find melanocytes, the specialized cells producing the skin pigment. These cells have dendrites, or appendages, which serve as conduits transporting pigment granules to the neighboring keratinocytes in stratum spinosum.
The melanin-containing granules are also called “melanosomes” and are wisely situated above the cells’ nuclei to protect the DNA.
Similarly, their number, size, and dispersion in the skin is the differentiating factor between the people of different skin colors.
The amount of melanocytes does not matter, as every one of us has the same amount. At the same time, skin pigmentation can be generalized or localized, depending on the area that had been stimulated to produce more melanin than the surrounding surface.
Likewise, it determines the shape of the distinctively pigmented region. The potential triggers for increased melanin production, besides the genetic material, are sunlight, inflammation, and hormonal imbalance.
How to know the depth of skin pigmentation?
The substantial majority of pigmented skin lesions springs from excessive melanin production. Simultaneously, not every melanocytic lesion has its source in the epidermis where melanin is most commonly stored.
Research shows that some hyperpigmentation causing factors like inflammation or UVA radiation can also disrupt the structure of collagen, a protein principally responsible for the healthy, firm architecture of the skin.
If the latter becomes disorganized, everything falls like dominoes from there. Provided that the skin integrity is disturbed, melanin may easily filter down into the dermis.
Contrarily, if the arrangement of the skin cells remains intact, melanin remains in the epidermis.
Based on whether the deposition of skin pigment occurs in the epidermis or the dermis, we can classify skin pigmentation as superficial or deep.
In a well-lit room, try lightly scratching the surface of your pigmented area, if it becomes lighter, chances are that it is superficial. While if it gets darker, most probably it is located in the dermis.
Concurrently, the lesions situated more superficially tend to disappear much faster, up to 4 weeks (the duration of skin cell turnover time) while the darker ones have a propensity to last much longer.
In parallel to that, not only melanin can be the pigment responsible for skin discoloration, this might pertain to blood as well.
Blood may also be temporarily stored in the dermis due to the disruption of blood vessels. Many people mistake transient erythema resulting from temperature changes or inflammation with hyperpigmentation.
The latter arises out of a transitory dilation of blood vessels which leads to an increased blood flow in the skin from the outside, and the skin becomes red. Sometimes, the skin may seem grayer and duller as well.
In such instances, the discoloration does not root from depigmentation but from excessively accumulated dead skin cells on the skin surface.
Different types of skin pigmentation
Accordingly, different variants of skin pigmentation may come in varying shapes, colors, and sizes. Hereunder, the list of its most frequently occurring types.
Melanocytic nevus is the most common pigmented skin lesion. Sometimes it is easily distinguished from other types of local discoloration, especially when it is dome-shaped. Nonetheless, when it is flat, it may be mistaken with, for instance, melasma.
In most cases, both lesions are of a brownish color. Nevertheless, naevi tend to be smaller and had been lasting for a longer period of time. Among naevi, prevalent freckles are to be found.
Simultaneously, naevi possess a proclivity to be intradermal hence of a longer duration period. Despite that fact, some still may affect the epidermis, in such cases, they are called epidermal naevi.
Post-inflammatory pigmentation is a frequent type of acquired skin pigmented lesions.
With time, we only become more and more exposed to the detrimental external irritants like pollution that lead to this kind of hyperpigmentation.
Very commonly, it also follows skin conditions that disrupt the skin’s integrity or cause inflammation like acne or lichen planus.
The usual dark hue is due to an increased amount of melanin in the basal layer of the epidermis.
When melanin tends to be dispersed throughout the layers of the epidermis, it imparts lighter to darker hues, while the bluish-gray color results from the pigment’s filtering to the dermis.
Melasma is a frequent consequence of various hormonal shifts, for example, hormonal imbalance occurring during pregnancy or when going on the pill.
Contrarily to the naevi, it tends to be singular, bigger, and is always at the level of the skin surface. Its brownish color is everything that differentiates it from the surrounding healthy skin.
Usually, it fades away sometime after the elimination of the causing factor. However, in some cases, it may persist for longer and affect one’s comfort in life.
Age spots appear in response to UVA radiation which, unlike UVB, penetrates deep into the skin.
For the same reason, the lesions also have a propensity to affect the dermis what makes them more durable and long-lasting.
Following the same logic, they tend to show up more often on the skin of the body parts which are exposed to the sun.
How long does skin pigmentation last if not treated or removed medically?
How long each case of skin pigmentation lasts when it’s not treated or removed, vastly depends on whether it affects the epidermis or the dermis.
The rate of deeper skin regeneration is not predicable nor constant. Even in patients with depigmentation of the same origin, no research comes up with an upfront, definite amount of time after which the lesion fades on its own.
Mostly, it fluctuates between months and even years. That applies to the skin pigmentation affecting the dermis. The regeneration period of the epidermis is much shorter though.
The skin cell turnover time, or the time needed by a skin cell to be produced and travel from the basal layer to the outermost stratum corneum, amounts to around 28 days.
Accordingly, after nearly a month, one can see the visible diminishing of the superficial skin pigmentation marks.
Nonetheless, certain lesions, including naevi, do not fade at all. Their removal is necessary in order to dispose of them for good.
Can skin pigmentation be treated or permanently removed?
Naturally, multiple skin pigmentation types can be treated or removed. Even if they are really resistant to treatment, the available options surely offer a notable alleviation of symptoms.
Sometimes, as mentioned previously, they disappear on their own after eliminating the triggering factor like stopping hormonal therapy.
It could be allowed to treat superficial discoloration or skin dullness at home. While therapy of more persistent and severe lesions should be consulted with a medical professional.
Depending on each lesion’s unique nature, there exist topical treatments that target different anchor points of skin metabolism.
In the case of, for instance, naevi, surgical removal may be necessary.
Possible treatments for different kinds of skin pigmentation
The vast majority of treatments for skin hyper-pigmentation embraces topical agents. Consequently, each of them affects a different anchor point of skin metabolism, whether it is melanogenesis, or skin pigment synthesis, skin cell proliferation, or differentiation.
Among the most popular options you can find:
Melanin is produced in melanocytes from one of the multiple amino acids, tyrosine. During the skin pigment synthesis pathway, an imperative enzyme called tyrosinase actively participates in the mentioned transformation.
Hydroquinone inhibits the action of the enzyme, therefore lessens the amount of melanin and thus melanosomes being created.
Simultaneously, it is considered one of the strongest whitening agents available to treat different skin pigmentation conditions.
It is effective against severe melanocytic lesions like persistent melasma.
Topical Retinoid Therapy
Topical retinoids also belong to some of the strongest agents against hyperpigmentation, nonetheless that of a slightly different origin than the one needing strictly whitening treatment.
The retinoid receptors (structures which retinoids bind to so that they can exert their effects), RARs, and RXRs are abundantly present in skin cells.
They are mainly responsible for the skin cell reparative process from photo-pollution or environmental damage.
Such an induced regeneration process includes stimulating the epidermal proliferation and differentiation, compaction of the stratum corneum as well as biosynthesis and deposition of glycosaminoglycans (compounds providing structure to the skin).
Therefore, retinoids not only stabilize the skin’s architecture by preventing deeper hyperpigmentation in the dermis but also promote the production of the new superficial skin.
They are effective both in age spots as well as in post-inflammatory hyperpigmentation conditions.
Other Topical Treatments For Hyperpigmentation
Besides the two most potent agents mentioned above, there exist other therapy options for the milder cases of hyperpigmentation.
They include tranexamic acid, arbutin, azelaic acid, glycolic acid, salicylic acid, kojic acid, and more.
Laser therapy can provide notable effects even when other methods had failed since it uses different wavelengths of light.
The medical professional can adjust laser intensity based on the depth and type of your skin pigment, from post-inflammatory hyperpigmentation, through melasma to melanocytic naevi.
A complete therapy consists of a series of treatments repeated over time with frequency assessed by the doctor.
Surgical therapy is mostly reserved for the complete elimination of pigmented lesions which are suspected to give rise to skin cancer in the future, including certain naevi.
Before a naevus is classified as one needing a prophylactic surgical removal, it is thoroughly examined by a doctor with the use of a dermoscopy.
Finally, to keep you calm before you panic, the surgeries are often quick and done under local anesthesia.