Presentation JR 2

8/18/2019 Presentation JR 2

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What Should Be Considered in Treatment of Melasma

Introduction

• Melasma is a common acquired hyperpigmentary disorder characterized

by light to dark brown macules and patches occurring in the sun-exposed

areas of the face and neck

• The major etiological factors include genetic inuences exposure to

ultra!iolet "#$% radiation and sex hormones

• &umerous treatment options including topical agents chemical peels and

laser treatments ha!e been tried for treating melasma

• To date no treatment for melasma has demonstrated truly satisfactory

results and so far none of these treatments ha!e been demonstrated to

pre!ent frequent relapses

• In this re!iew we discuss se!eral targets to be considered in treatment of

melisma

PART I

MELANIN AND MELANOCYTES IN

MELASMA

'( Is the current classi)cation of melasma !alid * speculation on the

signi)cance of dermal melanin

+( Increased epidermal pigmentation the hallmark of melasma

,( &ormal melanocytes and hyperacti!e melanocytes

'( Is the current classifcation o melasma vali ! s"eculation on the

si#nifcance o ermal melanin

• Traditionally melasma is classi)ed according to the depth of melanin

pigments into epidermal melasma dermal melasma and mixed type(

• It is generally belie!ed that the determination of depth of melanin pigment

is helpful in predicting the therapeutic outcome i(e( dermal melasma or

mixed type melasma is dicult to treat(

$uestion !

'( .hether we ha!e a reliable instrument to determine the depth of melanin

pigment *


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+( .hether there exists a true dermal type of melasma *

%hether &e have a relia'le instrument to etermine the e"th o

melanin "i#ment !

• .ood/s light examination 0

– 1pidermal melasma exhibits color enhancement of the lesion

whereas dermal melasma exhibits no enhancement of color(

• 2ecent reports ha!e suggested a poor correlation between classi)cation

based on .ood/s light examination and biopsy skin samples assessed

using light microscopy(

• .e examined the complete melasma lesion using in !i!o reectance

confocal microscopy "23M% it showed that the topographic distribution of

melanophages was !ery heterogeneous between one region of the

melasma lesion to another and e!en within a particular region of the

melasma lesion(

• This )nding suggested that a reliable classi)cation should be based on the

ratio of epidermal to dermal melanin in!ol!ing the whole lesional skin(

%hether there e(ists a true ermal t)"e o melasma!

• 4ermal melanophages are commonly found in the sun-exposed skin and

the normal facial skin has pigments in the dermis

• Melanophages were present both in melasma lesional and perilesional

normal skin in ,56 of 7orean patients

• Melasma is characterized by epidermal hyperpigmentation with or without

melanophages

• It needs to be further studied if this small amount of dermal melanin in the

melasma lesional skin does really a8ect the therapeutic outcome of the

treatment

*+ Increase e"iermal "i#mentation, the hallmar- o melasma

Increased epidermal pigmentation is the hallmark of melasma and must be the

main target for melasma treatment

• The true primary histological target in melasma treatment is the epidermal

melanin pigmentation in lesional skin

• 9lthough the long wa!elength laser targets the dermal melanin the

majority of the beam is absorbed by the increased epidermal pigments in

the melasma lesion


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.+ Normal melanoc)tes an h)"eractive melanoc)tes

• Melanocytes are responsible for increased epidermal pigmentation in

melasma

•

:ur recent transcriptomic study in '+ 7orean melasma patients con)rmedthat higher amounts of epidermal melanin are due to acti!ation of

melanogenesis in epidermal melanocytes

• In our study we found no signi)cant di8erence in the mean number of

MIT;-stained melanocytes in lesional skin compared to perilesional normal

skin

PART II

PAT/O0ENESIS O1 INCREASED

PI0MENTATION IN MELASMA

'( 2ole of blood !essels in the de!elopment of melasma

+(


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• =rostaglandins and 3:@+ are synthesized or upregulated in the skin during

#$ irradiation and a8ect melanocytes and pigmentation(

• It can be speculated that the role of steroids in treating melasma may

include blocking this process in melasma(

.+ Possi'le mechanism o melasma associate &ith se( hormones

• In !itro studies ha!e shown that cultured human melanocytes express

estrogen receptors(

• 1stradiol increases the le!el of melanogenic enzyme especially T2=-+ in

normal human melanocytes(

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Presentation JR 2