Volume 73, No.12: 2021 Siriraj Medical Journal
https://he02.tci-thaijo.org/index.php/sirirajmedj/index
841
Review Article
SMJ
Mohammad Ahmad Abdalla, Ph.D.
Department of Human Anatomy, Tikrit University College of Medicine, Tikrit, Iraq
Melasma Clinical Features, Diagnosis,
Epidemiology and Etiology: An Update Review
ABSTRACT
Melasma is one of the commonest dermatological challenges that facing dermatologists in the whole world.
Most of the previously published articles regarding melasma usually focused on its management and the newly
discovered drugs; however, the understanding of the suspected etiology and the pathogenesisis very critical to treat
this skin disorder in a correct manner. erefore, this review is an attempt to do a comprehensive updating on
the present understanding of the melasma epidemiology, etiology, its role in pregnant, post-menopausal women,
and in males, besides its clinical features and diagnosis through searching in many scientic databases including
EMBASE, Cochrane Library, PubMed, Pubmed Central (PMC), Medline, Web of Science, and Scopus.
is review approaches recognizing the pathogenesis that can provide ideas to solve the therapeutic problems
which connect to melasma. erefore, this article is entirely established on previously performed studies so that no
new studies on animal or human subjects were conducted by the author.
Keywords: Melanin; melanocortin; melasma (Siriraj Med J 2021; 73: 841-850)
Corresponding author: Mohammad Ahmad Abdalla
E-mail: dr.mohammad68@tu.edu.iq
Received 12 September 2021 Revised 28 September 2021 Accepted 13 October 2021
ORCID ID: https://orcid.org/0000-0001-8122-3692
http://dx.doi.org/10.33192/Smj.2021.109
INTRODUCTION
Melasma is one of the common acquired
hyperpigmentation conditions, mostly aects the face,
with a high prevalence among females and the darker skin
phenotype individuals.
1
Many etiologies, including family
history, hormonal inuence, and sunlight exposure, have
been involved in its pathogenesis.
2
e overall prevalence
reports wide ranges (1-50) %, because the values are
usually determined in a particular ethnic group within
a specic geographical area.
3
Histologically, melasma
may reveal enlarged melanocytes, increased dermal or/
and epidermal pigmentation, increased melanosomes,
dermal blood vessel, solar elastosis, and rarely perivascular
lymphohistiocytic inltrations.
4
Methodology
Melanogenesis
Melanogenesis is a process that occurs inside the
melanosomes. ere are two forms of melanin pigments
are produced within the melanosomes; pheomelanin and
eumelanin. Pheomelanin is a soluble sulfur-containing
bright red-yellowish polymer, while eumelanin is an
insoluble dark brownish-black polymer.
5
Tyrosinase is a
copper-containing enzyme; however, before tyrosinase can
act on tyrosine two cupric atoms present in tyrosinase must
be reduced to cuprous atoms. Tyrosinase is responsible
for the rst 2 stages in the synthesis of melanin; the
L-tyrosine hydroxylation into L-dihydroxyphenylalanine
(L-DOPA) with the following stage of oxidation for this
o-diphenol into the related quinone (L dopaquinone).
6
It
is worth noting that the L-tyrosine concentration required
for melanogenesis is determined by the conversion of
L-phenylalanine which is an essential amino acid through
the action of the intracellular enzyme phenylalanine
hydroxylase (PAH). e L-phenylalanine signicance in
melanogenesis is elucidated in phototypes of the skin I-VI
as the epidermal PAH actions are linearly correlated.
7
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Following the dopaquinone synthesis, the melanin
pathway is split into the synthesis of red-yellowish
pheomelanin and brownish-black eumelanin with
spontaneous conversion into dopachrome and
leucodopachrome. In the eumelanin formation pathway,
the dopachrome consider as either spontaneously
transformed into 5, 6-dihydroxyindole or it is enzymatically
transformed into 5, 6-dihydroxyindole-2-carboxylic acid
via dopachrome tautomerase (DCT), besides pointed out
as tyrosine-related protein-2 (TRP-2). e tyrosinase-
related proteins are of two types, TRP-1 and TRP-2 that
are structurally associated with tyrosinase.
8,9
TRP-1 and TRP-2 are melanosomal proteins that
extend to the membrane of the melanosome like tyrosinase.
ere is a suggestion that TRP-1 elevates the eumelanin
to pheomelanin ratio. Also, they may be explaining the
high tyrosinase stability. Ultimately, the quinones and
indoles polymerization results in eumelanin synthesis.
10
e pathway of pheomelanin branches from that of
eumelanin at the step of L-dopaquinone and it depends
upon the cysteine existence that shows active transporting
through the membrane of melanosomes. e L-dopaquinone
interacts with cysteine to produce cysteinyl-dopa, which
is then converted into the quinoleimine and alanine-
hydroxyl dihydrobenzothazine that polymerized to
pheomelanin. Besides, the tyrosinase enzyme may be
indirectly triggered by the tyrosine hydroxylase isoenzyme
1 (TH1) which exists in the melanosomes that catalyze
L-dopa formation. In turn, the latter L-dopa may play
a role as the tyrosinase substrate.
11
Redox (Reduction Oxidation Reaction) status
within melanosomes is important for the equilibrium
between the pheomelanin and eumelanin synthesis.
is pheomelanin or eumelanin synthesis is directly
aected by the glutathione (GSH) level, the low GSH
level related to pheomelanin, and the high related to
eumelanin. erefore, the functional and expressional
activities of the antioxidant enzymes like glutathione
reductase, glutathione peroxidase, thioredoxin reductase,
and catalase are most likely modifying the melanosomes
pathway.
12
Each melanocyte that establishes at the basal layer of
epithelium together with its dendrites reacts with about
thirty-six keratinocyte cells to transmit melanosomes
and cause skin protection from the ultraviolet radiation
and photo-stimulated carcinogenesis. Besides, the type
and amount of melanin synthesized and transferred
into the keratinocyte cells with successive aggregation,
incorporation, and degradation aects the epidermis
coloration.
12
The ratio of eumelanin to pheomelanin varies
dramatically in the various skin phenotypes, found at
the lowest level in type I and II and highest in type V
and VI; and these types are:-
1. Type I :- (score ranges 0-6) never tans, always
burns (pale white; red hair or blond; blue eyes; with
freckles).
2. Type II :- (score ranges 7-13) minimally tans,
usually burns (white; fair; red hair or blond; hazel, green
or blue eyes).
3. Type III :- (score ranges 14-20) uniformly tans,
sometimes mildly burns, (creamy white; fair; with any
eye or hair colour).
4. Type IV :-(score ranges 21-27) always tans,
minimally burns (moderate brown).
5. Type V:- (score ranges 28-34) very easily tans,
very rarely burns (dark brown).
6. Type VI:- (score ranges 35-36) never tans, never
burns (deep pigmented darkish brown to darkest brown).
13
Fig 1. Melanin synthetic pathway
5
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Review Article
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Melasma
e term “facial hyperpigmentation” or “melasma”
is obtained from the Greek word “melas”, meaning
“black”. It also refers to “chloasma gravidarum” or “the
pregnancy mask”. Its onset starts commonly during
the 2
nd
half of gestation, and it exists in 40-75% of all
pregnancies. It occurs usually in dark hair, brown eyes,
and dark-epidermis women. e main variations of
melasma prevalence in various studies were accredited to
the proven fact that explaining the pigmentary alterations
are more visible in individuals with fair skin.
14
Melasma commonly inuences the principal photo-
exposed skin regions, particularly the facial and neck
areas. e commonly involved sites include the cheeks,
chin, forehead, nose, upper lip, and temples; while the
rarely involved sites may distress the sternal region and
extensor arms. However; this condition considers as a
benign disorder that usually with aesthetic implications
only, but it can inuence the self-esteem and self-image,
with negative eects on an individual’s life quality.
15
Clinical features of melasma
Melasma is localized at sun-exposed regions, where
symmetrical light or dark brownish conuent macules or
punctate are present, most sharply delimited, particularly
on the cheeks, forehead, chin, and upper lip. ere are three
kinds of melasma lesions; centrofacial type (implicates
cheeks, forehead, nose, chin, and upper lip), mandibular
type (over the mandibular ramus), and symmetrical
malar type (localized to nose and cheeks).
8,12,16
In male
individuals, the malar type is the commonest, while the
centrofacial is the common type revealed in females.
Wood’s lamp may clinically divide the pigmentation
depth; in the epidermal type may be shown highlighting
multiple pigments in (50%) of cases, compared to dermal
type (5%), were not.
17
While the mixed type in (45%) of
all cases just a partial pigmentation highlighting is found.
Clinically, the dermal type becomes mildly visible bluish
because of the Tyndall eect. e disease severity may
be objectied with Melanin Index (MI) estimated by
specic tools, Melanin Area and Severity Index (MASI)
determining the regions and densities of involvements,
with patient self-evaluations.
18,19
Extra-facial melasma includes many features such
as irregular, hyperchromic, symmetrical discolorations
at the neck, cervical, sternal areas, arms, forearms,
and eventually at the back. It aects the upper limbs
predominantly among old adults, menopausal women,
and those receiving hormonal replacement therapy.
20
Diagnosis of Melasma
1. Melasma examination under normal light
e skin of melasma lesion is inspected by natural
solar radiations, the macular lesions have irregular, quite
sharply demarcated borders with a “stuck on” appearance
e hypermelanosis type can be epidermal (brownish),
a dermal (bluish-gray), or a mixed (brownish-gray).
7,21
2. Wood’s lamp examination
is procedure used to evaluate the melasma
clinical status, depending upon Wood’s light (320-400
nm) and four types of melasma can be recorded:-
A. e epidermal type: has increased melanin
in suprabasal, basal, and stratum corneum layers. e
pigmentary lesions are emphasized with Wood’s light.
B. e dermal type: does not show enhancement
with the Wood’s light. Melanophages exist in the deep
and supercial dermis.
C. The mixed type: the dermal and epidermal
pigment type that shows no or slight enhancement with
the Wood’s light.
D. Wood’s light unapparent is seen in dark individuals.
As the Wood’s lamp was utilized to determine
the melanin pigment situation either in the dermis or
epidermis (i.e. dermal versus epidermal melasma), the
histopathological and confocal microscopy reports
revealed that it is usually a mixture from the two types
in the same patient even they have only epidermal type
by Wood’s light.
8,9,17,22
3. Hormonal assay
e hormonal level assessments can be guaranteed
because of the activity of hormones imbalance in melasma
disease. FSH, LH, MSH, progesterone, thyroid, and prolactin
hormones level must be estimated, just if indicated.
23,24
4. Microscopic histopathology
Melasma may be clinically diagnosed; however,
the histological report may be also helpful. e histological
ndings are the same in both males and females. Furthermore,
the histopathological features of melasma in males are
still unclearly dened. ese features include attening in
the rete ridge, solar elastosis, and mild inltrations of the
inammatory cells.
25
e amount of melanin is raised in
the dermis or epidermis or even in both. In the epidermis,
it presents in the keratinocyte cells of suprabasal and basal
layers. e number of melanocyte cells is not increased
but these cells are larger in size with more dendrites,
greater melanosomal size, and; therefore, more activity
will be produced. Dermal melanin amount increased in
the middle and supercial dermis in macrophage cells,
usually in aggregation at areas nearby the small dilated
blood vessels. The epidermal melanization with the
existence of melanophages at papillary dermis may be
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revealed in Fontana-Masson and Haematoxylin-Eosin
staining.
26
ere is no proof of degeneration in the basal
layer was recorded. Signicantly elevated expressions
for Stem Cell Factor (SCF) allover broblasts in the
dermis with its C-kit receptors at the epidermal basal
layer were present in diseased skin in comparison with
non-diseased.
27
Several special stains are present that facilitate
the light microscopic visualization of melanocytes and
their products including; silver stain, dopa reaction, and
Fontana-Masson. Histologically, two types of pigmentation
had been characterized, dermal and epidermal.
11
Epidermal melasma appeared to be the most
predominant type proceeded by mixed type. While
melasma has classically been classied as epidermal- or
dermal-based on the presence or absence of Wood’s
light enhancement, respectively, most cases show both
epidermal and dermal melanin. Dermal melanophages
are a normal nding in sun-exposed skin.
17,22
Increased melanophages may also recognize
in several melasma individuals by reectance confocal
microscopy (RCM) examination. Interestingly, RCM
examinations revealed that the topographic distribution
of the melanophages is very diverse from one lesional
area to another and also within the same lesional area.
ese ndings supposed that histological classications
(dermal, epidermal, and mixed) regarding the depth of
the pigment utilizing a single specimen of skin biopsy can
be very risky. A reliable classication could be dependent
upon the dermal/epidermal melan in ratio present over
the entire involved skin area. Until nowadays, it is not
clear, if the origin of dermal pigments comes from
the epidermal layer. Besides, it is unclaried if dermal
pigments may be resolved spontaneously when they are
not supplemented from epidermis. In darkly pigmented
individuals (e.g. those with indeterminate melasma), a
skin biopsy is occasionally performed before treatment
is initiated.
6,28-32
5. Electron microscopy
It shows high amounts of melanin within all layers
of the epidermis and also within the dermis, according
to the melasma histological type. Also, the numbers of
melanocyte cells included the high numbers of melanosomes
compared to melanocyte cells of the normal skin is high.
It may reveal the increased melanosomes were associated
with ndings of many organelles in the melanocyte cells
from the diseased lesions. e melasma lesions included
more Golgi apparatus, mitochondria, rough endoplasmic
retinaculum, dendrites, ribosomes, and supposing more
production ability of those cells.
33,34
6. Immunohistochemistry
It may show high expression for stem cell factor
in the dermal layer and for c-kit in epidermal layer with
high expression for vascular endothelial growth factor,
which can be the main factor achieved in the changed
blood vessels occurs in melasma.
27,35-37
7. Dermoscopy may play a principal role in melasma
diagnosis and in demonstrating the melanin pigment
deposition level. e main ndings include pigmented dots,
globules, more prominent vascularity, and telangiectasia.
Also, the accentuation for the pseudo-reticular pigmentary
network and Owl’s eye structures exist. In addition,
dermoscopy can be used in the assessment of melasma
severity.
38,39
Epidemiology of melasma
Although melasma may inuence individuals from any
race, it is usually common among darker skin phototypes
and the commonest in persons with Fitzpatrick IV-VI
skin types.
4
In a random study including self-recording for
melasma among Hispanic female individuals, it reported
that the incidence about 8.8% but the previous incidence
was 4%. A survey among Arab Americans who lived in
the USA mentioned that the h commonest skin disease
was melasma with 14.5% from a surveyed population,
12
while another study screened 200 persons with melasma
found men demonstrated 20.5%.
20
Another published
article reported the results of three studies that estimating
the incidence of melasma among adult males of Latino
laborers with 36.0%, 7.4%, and 14%.
11
e average age in
aected males was 33.5 years and the duration was about
3.5 years; however, it may be present also among older
males and for more periods.
9
It may cause embarrassment
in men due to its awful-looking; and a general community
stigma that classied it as a disorder or disease when aects
pregnant women. It was recorded that its prevalence
up to 75% among pregnant women, but it exists rarely
before puberty and; therefore, it most commonly starts
in the reproductive years of life.
40
Melasma has recognizable psychological inuences
and signicant emotions on aected individuals. e
eect on the life quality of individuals with melasma
may be standardized by the Melasma Quality of Life
Scale (MELASQOL) or/and by the Dermatology Life
Quality Index (DLQI); the individuals who have high
DLQI scores signify poor Quality of Life (QOL).
18
Etiology of melasma
e exact causes of melasma have not been dened,
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but numerous factors are possible to be suspected
including genetics, pregnancy, cosmetic use, sun exposure,
antiepileptic medications, oral contraceptives, and thyroid
dysfunction.
41
Among these factors, the following are
the most important:-
1. Risk Factors
e precise melasma cause is still undetermined;
even numerous factors may be involved in this lesion’s
pathogenesis. ese factors are implicated as etiologic or
genetic predispositions and inuences, in approximately
40% of melasma individuals there is one relative at least
aected with this lesion.
4
Other factors inuencing the
onset or/and triggering its onset including hormonal
alterations during gestation or hormonal therapy,
exposure to UV radiations, phototoxic drugs, cosmetics,
chemicals, steroids, antiseizure therapy, and darker
skin colorations.
32,42,43
Psychotropics and anxiety traits
may be strongly related to melasma development; so
that melasma is regarded as “the stress mask”. All the
previously mentioned factors are suggested to cause an
increment in both melanocytosis and melanogenesis, the
primary histological disturbances revealed in melasma.
Furthermore, although its pathogenesis is unknown yet,
the above factors are considered to trigger the disease in
a population with genetic predispositions. Study of those
factors may urge physicians to get better improvement
for preventative measures, management of melasma
individuals, expectation treatment result, and disease
recurrence.
20
e lesion onset is usually proved by deteriorated
stratum corneum layer integrity with the overdue barrier
recovery period, while a high amount of different
inammatory cells that exist in the lesional region are
the common ndings distinguished during melasma
development in Asian population skin.
10
2. Endocrine factors
e levels of hormones either because of hormonal
therapy or during pregnancy periods are regarded to be
one of those most inuencing factors or even the most
remarkable factor on the onset and melasma development.
During pregnancy, endocrine, immunologic, vascular,
and metabolic alterations increase the susceptibility of
pregnant women to obvious alterations in the skin with its
related appendages.
44
Progesterone, estrogen, and alpha-
MSH which are commonly elevated during pregnancy
time and especially at third trimester, are supposed to
stimulate the melasma onset by for example through
estrogen tentative pathway III that causing increase
tyrosinase enzyme and melanosome transfer (Fig 2). Even
with the multiple and various cases that found, no high
levels for the mentioned hormones proved. However,
several researchers believed that hormonal changes with
increased Luteinizing Hormone (LH) and decreased
estrogen levels, as a result of ovarian dysfunctions, can
underlie the pathogenesis process in some conditions
of the idiopathic melasma.
16,22,24
Fig 2. Tentative pathway III of the estrogen
25
In addition to pregnancy, women taken contraceptive
pills with progesterone or women at the post-menopausal
period taken progesterone as hormonal therapy, the
extra-facial melasma was usually common among them,
therefore; the progesterone regarded as a principal factor
in this disease. Impressively, the hyperpigmentation
resulted from sequential or combined contraceptive pills
are incompletely regressing aer ceasing, contrary to
melanoderma of pregnant women. Researchers; however,
have mentioned that estrogen receptors and progesterone
receptors expression at melasma-aected regions need
more investigations and clarications, these researches
can cause better development for the topical anti-estrogen
therapy of melasma.
7,19,45
e thyroid autoimmune characteristic is also regarded
as another important element in the melasma onset
because a signicant number of Hashimoto’s diseased
women get melasma and also those women who get
the disease during pregnancy, will or even already have
thyroid autoimmunity.
28
Finally, other factors have been involved having the
main role in melasma development, like melanocytic nevi
and lentigines. Although, the presence of these factors
is not very closely connected to the disease onset and its
development, like the previously mentioned factors; on
the other hand, melasma is usually revealed in women,
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some articles have been done on men with melasma. In
those articles, the most remarkable factors indicated for
melasma development are regarded to be the usage of
cosmetics, sunlight exposure, familial hyperpigmentation,
hepatic disorders, and infections.
9,11,21,46-48
Even there are
a few studies that suggest the circulating LH is crucially
increased in melasma men, while testosterone is remarkably
decreased in the very same category, information that
assumes that melasma can implicate precise testicular
resistance.
4
3. Genetic factors
e skin phototypes III, IV, and V with the
female gender regarded as the most recognized genetics,
other inheritable characters, probably multi-genetic.
One of the most important international researches in
this scope was carried out in dermatological centers of 9
countries (USA, Germany, France, Mexico, Netherlands,
Singapore, Italy, Hong Kong, and South Korea) and
exhibited that 48% from 324 melasmic females had a
positive familial history of this disease. Also in about 97%
of total cases, another family member from the rst degree
of relativity is aected.
48
Epidemiological information in
this consideration may seriously dier in other countries
individuals: the prevalence of positive familial history
recorded in literature are 70.3% in male individuals and
56% in female individuals in Brazil,
40
54.7% in Iran,
23
33% in India.
49
Although scattered and occasionally not
implicating large patient’s sample, these articles that
reveal important variations even between individuals
living in the same environmental situations, suppose
that the susceptibility to melasma lesion is polygenic and
might be also aected by the epigenetic modulations of
melanogenesis. A study reported that expression of 16
microRNA (miRNA) could dier between the melanocyte
cells managed with (forskolin and solar-stimulated UV
radiation) from untreated melanocyte cells; one of those
miRNAs, known as miR-145, was remarkably down-
regulated and also capable of aecting the expression of
some main pigmentary genes (Tyr, Trp1, Rab27a, Sox9,
Mitf, Myo5a, Fscn1).
50,51
4. Sun exposure
e most principal and obvious environmental
stimulating factor for melasma is sunlight exposure.
Among the various constituents of sunlight, UV radiation
(A and B) has the main role; since they may induce or
increase melanogenesis, migration directly, and melanocyte
proliferations, but even indirectly, through triggering the
formation of endothelin 1, interleukin 1 (IL-1), ACTH,
and α-MSH by keratinocyte cells.
52-54
e major role for the visible and the infrared
radiation in the melanogenesis process is less remarkable,
but not negligible; an association between occupational great
exposure to the heat or the intense articial lighting and
exacerbation of melasma or/and low react to management
was recorded by several researchers.
4
e indirect proof
for the eect of the visible light revealed that the sunscreen
compounds causing absorption for ultraviolet irradiations,
and also the visible light reinforces the depigmentation
eect for hydroquinone further than the sunscreen that
blocks UV radiation only.
32,55
e UV light is regarded as another important
agent or factor that has a specied and proven role by
multiple previous studies and also case reports.
12,13,39
e UV light is not regarded to be capable to develop
melasma without any hormonal changes or genetic
predispositions, but it is supposed to be essential in
stimulating the lesion when the background presents.
Apart from the genetic predispositions, autoimmunity
and systemic disorders are highly associated with the
development and appearance of the lesion. Systemic
disorders like Addison’s disease could almost always be
doubtful and required exclusion in the clinically relative
cases.
22,28
5. Drugs
Melasma-like pigmentation has been noticed in
individuals taking antiepileptic drugs like phenytoin or
mephenytoin. Chlorpromazine and related phenothiazines
may induce pigmentations at sun-exposed parts of
skin especially those who received high doses for long
periods. Other drugs include anti-tumor agents like
cyclophosphamide, bleomycin, and adriamycin.
4,7,56,57
In order to induce skin hyperpigmentation,
sometimes even more than a single mechanism is
involved. The tetracycline especially minocycline,
tricyclic antidepressants particularly imipramine and
desipramine, antimalarials, cytotoxic drugs, phenothiazines
mostly chlorpromazine, amiodarone, anticonvulsants,
sulfonylureas, and clofazimine are all could be listed as
the drugs stimulating hyperpigmentation. Clofazimine
stimulated pigmentations is a brown color, claried in
sun-exposed regions, sometimes unrecognizable from
melasma. In most cases, those lesions are accompanied by nail
involvement. e xed drug eruption considers as a clinical
distinctive kind of drug-stimulated hyperpigmentation
presented by recurrent plaques in the same situations.
It more frequently implicates genitalia, acral areas, and
the lips. Many medications may develop this disease,
but the greatly remarkable are sulfonamides, ibuprofen,
and barbiturates.
8,10,39,41,58,59
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6. Cosmetic
ese include a wide variety of perfumes, soaps,
creams, powders, shampoos, that contain psoralen, tar
derivatives, or hexachlorophene substance which are
photodynamic that may cause facial pigmentation.
45
However, the pigmented cosmetic dermatitis
consider as a variant of the pigmented contact dermatitis
because the cosmetic ingredients are the primary allergens
where the face is predominantly involved. Clinically, the
patchy or diuse brown hyperpigmentation presents
over forehead and/or cheeks or the entire face making
it hardly dierentiate from melasma.
60
7. Idiopathic
Most cases among males and at least one-third
of all cases among females are idiopathic.
18
Melasma in pregnancy, post-menopausal women, and
oral contraceptives role
During pregnancy, particularly in the third trimester,
females have elevated levels of pituitary, ovarian and placental
hormones, which exhibit a trigger for melanogenesis
that can describe the relations between pregnancy and
melasma.
23
High levels of progesterone, estrogens, and
MSH also cause an increment in the transcription of
dopachrome and tyrosinase tautomerase that can be
implicated in developing pigmentations in this specic
period.
61
ose ndings suggest that melasma lesions in
pregnant women are more possible to be related to the
circulated female hormone than the MSH peptides. In
fact, the high levels of progesterone, which occurs during
pregnancy; and the estrogen formation, which takes
place from the 8
th
till the 31
st
week of gestation mirrors
the perfect progressive patterns of hyperpigmentation.
In melasma, the major role of female hormone onset is
proposed by its increased incidence in women getting
exogenous progesterone or/and estrogen and its association
with the menstrual period.
4,11
e onset of melasma mostly happens during the
2
nd
half of pregnancy and it may be present in 40-75%
of all pregnancies.
23
On contrary, a study done on 324
women who managed melasma disease in nine dierent
clinics worldwide, recorded the melasma onset in 25%
of females aer using the OCP, in 27% of females during
gestation, and in 41% of females aer gestation.
48
Melasma continues aer gestation among less than
10%, though a single study report existence in about 30% of
cases aer ten years. If the melasma continues postpartum,
some females notice a premenstrual hyperpigmentation
are. Regarding that UV exposure triggers up-regulation
of melanocyte cells and their activity in the pathogenesis
of melasma, susceptible females could be recommended
to protect unavoidable heavy sunlight exposures and
guarantee preservation with broad-spectrum (UVB and
UVA) sunscreens and suitable clothing.
32,54
As the female sex hormones that exist within OCP
show to be principal for melasma development, the same
association could be expected in postmenopausal females
on Hormone Replacement Therapy (HRT). Indeed,
there are some case reports for melasma present in the
postmenopausal. Melasma in the forearms appears to
be a comparatively common sign particularly in old age
individuals and postmenopausal females using estrogen
therapy supplementations. As several of those persons
had melasma in the face when young that may explain
the presence of people with estrogen-sensitive melanocyte
cells in forearm skin that show maturation at an older
age.
8,9,12,25
Tamoxifen considers a Selective Estrogen
Receptor Modulator (SERM) and spends mixed estrogenic
with antiestrogenic actions depending upon the tissues
and cell types.
57
Melasma in male
Some articles of melasma developing in men were
available; in 1957, the rst recorded male melasma case
was in a French primary hypogonadism man, presented
with low testosterone level and high FSH and LH.
62
Similarly, another study was done on een Indian men
who had idiopathic melasma, characterized by a low level
of testosterone and high level of LH in comparison with
same age controls; the estrogen level was undetected.
20
In another study, a melasma case aer oral therapies
with triggers for production of testosterone, a compound
containing indole-3-carbinol, androstenedione,
dehydroepiandrosterone (DHEA), and Tribulus Terrestres,
which is a gonadotropic trigger that elevates LH secretions.
39
Melasma and the pituitary gland
e melanocortins produced from intermediate lobe
of the hypophysis gland, they regarded as a group of peptide
hormones important for melanogenesis that activate the
formation and release of melanin by melanocyte cells
situated at skin and hairs. e melanocortins contain three
dierent kinds of MSH (α-MSH, β-MSH, and γ-MSH) with
ACTH; all of them are obtained from a similar precursor,
the proopiomelanocortin prohormone (POMC), which
secretions are stimulated by the Corticotropin-Releasing
Hormone (CRH) created within the hypothalamus.
4,52
In humans, ACTH and α-MSH are also created
regionally in skin (both within keratinocyte and melanocyte
cells) and have main roles in pigmentation, probably
via autocrine or/and paracrine mechanisms. e CRH
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848
expression with CRH receptors found in the normal
human melanocyte, melanoma, and nevus cells. e
plasma immunoreactive β-MSH measured for individuals
with/without melasma getting progesterone alone or
a combination of estrogen-progesterone therapy; the
β-MSH level was indierent from gender and age-matched
control group.
7,12,53
It is essential to recognize melasma that is located
mostly on the face and less considerably on neck or
forearm, from the generalized hyperpigmentation due to
some adrenal or pituitary disorders causing high levels
of MSH and POMC-obtained ACTH with subsequent
universal skin hyperpigmentation. The individuals
inuenced by major adrenal insuciencies, ACTH-
depending Cushing’s and Nelson’s syndromes, diagnosed
by increased POMC-obtained ACTH levels.
4,7,22,56
CONCLUSION
Melasma is a clinical condition caused by multiple
factors and etiopathogenetic mechanisms that are required
in order to understand more eective management. e
discovery of recent pathways and pathogenic mechanisms
is essential in collocation the way for recent more eective
melasma treatment agents or procedures. e pathogenic
melasma mechanisms might be heterogeneous in various
ethnic groups among the population. is review approaches
toward recognizing the pathogenesis that can provide
ideas to solve the therapeutic problems that connect to
melasma. erefore, this article is entirely established
on previously performed studies so that no new studies
on animal or human subjects were conducted by the
author.
ACKNOWLEDGMENTS
e author would like to thank Tikrit University
College of Medicine (TUCOM) for its technical and
editorial assistance.
Conict of interest: None declared.
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