Solar lentigines are more than just spots, they only disappear when an effective instrument is used.
The effectiveness of the laser is the possibility of removing them with less inflammation and being able to maintain the result.
Solar lentigines are usually persistent with the most diverse treatments and their complete and long-term elimination can cause areas without pigment.
It is for this reason that many doctors and aestheticians choose temporary solutions such as trichloroacetic acid (TAA). Peelings
ATA causes a chemical burn at the application site.
It is difficult to perform on very pigmented skin because it is more likely to cause post-inflammatory pigmentation.
Laser is used to permanently remove them. Laser rejuvenation
Lentigines are more than just spots, the presence of warts has been demonstrated in viral cultures of “lentigines” (See reference #5) doi:10.1016/S0923-1811(03)00002-1
Why is laser used?
The laser is the only instrument capable of covering large areas and also removing the deeper parts.
Shorter recovery periods are achieved.
It’s easier to touch them up when they reappear.
Solar or senile lentigines are caused by a mismatch in the growth of the basal layers of the epidermis. (1,2).
Various stains using markers (immunohistochemistry) have elucidated some histological aspects that have always created confusion.
The “hallmark” for defining a lentigo is the presence of an increase in pigment in the basal melanin. Structure of lentigos
It has always been considered that the increase in lentigo pigment includes a greater number of pigment cells (melanocytes) and a greater elongation of the dermal buds (dermal papillae).
Findings shared by childhood lentigo (simple lentigo) and senile lentigo.
However, it is more difficult to explain all the findings specific to senile lentigo, since, from an increase in the dermal papillae, we move on to include a greater thickness of the granular layer, which contains the precursor of keratin, keratohyalin. The layers of the skin
Let us consider again the point of why there is more pigment. Increased melanin production or “retention” of the pigment?
A freckle is a larger accumulation of pigment generated by an increase in the production of melanin by melanocytes, which do not increase in number or size. The other layers of the skin are not altered, they simply receive more pigment.
If we focus on the increase in the granular layer we will find the key, excluding for a moment other changes such as, the increase in the thickness of the corneal layer (hyperkeratosis), increase in melanocytes (not always present).
How do skin spots originate?
What really happens with lentigines…
The disorder begins with the elongation of the epidermal ridges due to an increase in the thickness of the basal layers (acanthosis).
In later stages, the skin tends to flatten or even sag as a result of coexisting atrophy (2)(3).
One of the components of the classical descriptions of lentigines was that there was an increase in melanocytes.
However, this is relative, since a structural change of the epidermis occurs according to analysis with genetic markers and immunohistochemistry performed by Dr. Choi’s group (4).
Choi (4) found no significant differences in the ratio of melanocytes to keratinocytes when comparing lentigo skin with apparently healthy skin.
None of the specific markers for melanocytic genes showed a significant difference in their expression.
Specific markers for keratin 5 and 10 (KRT5, KRT10) suggest that the cells of the suprabasal wall of lentigines have a slower turnover.
Hyperpigmentation is caused more by an accumulation of melanin “stuck” in the basal layers than by an increase in its production.
References
- Goorochurn R et al. Biological processes in solar lentigo: insights brought by experimental models. Exp Dermatol. 2016 ;25(3):174-7.
- Lin CB et al. Immuno-histochemical evaluation of solar lentigines: The association of KGF/KGFR and other factors with lesion development. Journal of Dermatological Science. 2010; 59: 91–97.
- Yonei N. Two patterns of solar lentigines: a histopathological analysis of 40 Japanese women. J Dermatol. 2012;39(10):829-32.
- Choi W. Molecular and histological characterization of age spots. Exp Dermatol. 2017;26(3):242-248.
- Akiyo Gushia,b,*, Takuro Kanekuraa, Tamotsu Kanzakia,, Yoshito Eizurub. Detection and sequences of human papillomavirus
DNA in nongenital seborrhoeic keratosis of immunopotent individuals. Journal of Dermatological Science (2003) 31, 143/149