Download An overview of ethnic skin disorders in black Africans of Sierra Leone

SKIN CARE
Arfan Ul Bari
An overview of ethnic skin disorders
in black Africans of Sierra Leone
(West Africa)
ARFAN UL BARI
Department of Dermatology, Combined Military Hospital Peshawar, Peshawar, Pakistan
ABSTRACT: Physical differences among human
populations may lead to variable prevalence and
presentation of skin disorders in different ethnicities.
Disease pattern in a given ethnic population is generally
determined by different ecological and socioeconomic
factors. Eighty percent of the world's population consists
of individuals with pigmented skin. Darker skin differs from
Caucasian skin in its reactivity and disease presentation.
Darker skin, if on one hand, is a blessing as it relates to sun
damage and aging, on the other hand it can be a curse
for being vulnerable for excess melanin and collagen
production resulting in wide range of skin disorders. This
differential prevalence of dermatological disorders in
different ethnic populations points towards some social,
cultural and environmental factors in addition to genetic
factors in causation of these disorders. This is a minireview of various skin disorders along with possible
etiological factors prevalent in black population of Sierra
Leone; a country located on the west most corner of
Africa along costal line of Atlantic Ocean. Investigative
and therapeutic aspects of these skin disorders are not
touched as it was beyond scope and needed another
review article.
KEYWORDS: ethnic dermatology, ethnic skin disorders,
black Africans.
INTRODUCTION
Majority of the world’s population consists of people with dark
skin. Fitz-Patrick skin types IV, V and VI constitute nonCaucasian darker skin types (1). An individual with an olive skin
tone, also characterized as beige or lightly tanned, is classified
as having type IV skin; those with brown skin as type V; and
black skin as type VI. These skin types rarely or never burn on
sun exposure and tan readily. Peoples in this category include
those from Asia (South Asia, Southeast Asia and East Asia),
Hispanics and Blacks. The black race can be divided into:
Africans blacks, Afro-Caribbean and African Americans
blacks, which is a composite of number of different races (1,
2). Darker skin differs from Caucasian skin in its reactivity and
disease presentation. Ethnic differences in skin properties may
explain racial disparities seen in dermatologic disorders. Skin
colour is determined by cells called melanocytes. It is well
established that there are no racial differences in the number
of melanocytes (3, 4). There are more and larger
melanosomes in darker-skin melanocytes than in those of
lighter skin. Racial and ethnic differences in skin colour are due
to variations in the number, size, and aggregation of the
melanosomes within the melanocyte and keratinocyte (3-6). In
addition to differences in the grouping of the melanosomes,
an increased number of basal layer melanosomes (340 per
basal cell) has been reported in dark-skinned black subjects
compared with the light-skinned black subjects (120
melanosomes per basal cell) (7) Other physical differences
include variability in hair structure, fibroblast and mast cell size
and structure in people of colour compared with fair-skinned
persons (8). These differences could at least in part account
for the lower incidence of skin cancer and a lower incidence
and different presentation of photo aging in certain people of
colour compared with fair-skinned persons (9-10). On the other
hand, a higher incidence of pigmentation disorders and of
certain types of alopecia in people with skin of colour
compared with those of other ancestry may also be explained
logically (11-12).
PATTERN AND FREQUENCY OF DIFFERENT SKIN DISORDERS
Disease pattern in a given population is generally determined
by different demographic, ecological and socioeconomic
factors (13, 14). Black skin, if on one hand, is a blessing as it
relates to sun damage and aging, on the other hand it can be
a curse for being vulnerable for excess melanin production
(resulting in dark patches) or excess collagen production
(resulting in keloids/hypertrophic scars) (14, 15). Certain
biological and structural differences seen in black ethnic skin
along with demographic and environmental factors leads to a
different pattern and frequency of skin disorders in black
Africans than that from other ethnicities, e.g, Caucasians,
Hispanis and Asians (12, 15-17). Table 1 shows the comparison
of commonly occurring skin disorders in different ethnic
populations. The present article will focus more on pattern
seen among black Africans of Sierra Leone. We see that most
prevalent skin disease is fungal infection (42.3 percent)
followed by hair disorders (9.7 percent), sexually transmitted
infections (9.2 percent), acne/folliculitis, (7 percent), parasitic
infections (6.6 percent), scars/keloidal disorders (5 percent)
and pigmentary disorders (4.5 percent). This pattern of
frequency was found quite different from that seen in
American blacks, Hispanis and Asians. This disparity is most
likely due to geopolitical, environmental and socioeconomic
conditions of the region (12, 13, 15-18). Different categories of
skin disorders along with frequency of their occurrence are
shown in Table 2.
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SKIN CARE
occurring anti-infective agent in their diet, secretion of some
potent anti-septic/ anti-infective agent in their sweat or some
genetic factors contributing to the resistance against these
infections15. Hot humid weather could be another reason for
decreases prevalence of viral infections especially with herpes
virus (23).
Table 1. Comparison of frequency of common skin disorders in
various ethnic populations (17, 21, 23, descending order).
Table 2. Frequency pattern of of various disease categories (in
descending order).
INFECTIVE SKIN DISORDERS
A variety of cutanoeus infections are seen in people of African
region due to geographical, environmental and social factors
(Figures 1 and 2ù ) (14, 16, 17). A very high prevalence (61.7
percent) of infective disorders has been observed in Africans of
Sierra Leone (17). Table 3 elaborates composition of various
Infective disease categories. Amongst infective skin disorders,
fungal infections, predominantly of superficial type are the
commonest in African populations. Geographical factors such as
season and climate (heavy rainfall during 9-10 months in a year)
probably contribute to this high incidence. Second highest
prevalence is of sexually transmitted infections (STIs) including
gonorrhea and syphilis and HIV infection. Parasitic infections,
especially onchodermatitis was the next common disease which
is endemic and a major public health problem in many countries
in Africa, including Sierra Leone (19). It is a chronic, multi-systemic
parasitic disease caused by the nematode Onchocerca volvulus
and is transmitted by a black fly (Simulium damnosum). An
extended clinical spectrum of the cutaneous disease caused by
this nematodal infection includes; acute papular
onchodermatitis, chronic papular onchodermatitis, chronic
lichenified onchodermatitis, sowda, lepord spotting, lizard skin,
hanging groin and onchocercoma (19-20) (Figure 2 ù ).
Surprisingly, a significantly less number of bacterial, viral and other
parasitic (except onchodermatitis) infections are seen black
African population (15, 21, 22). In a recent study conducted in a
coastal city of Mangalore in India (22) (having the similar hot
humid climate as in African country of Sierra Leone) fungal
infections constitutes the commonest infective dermatoses and
split up of fungal infections is similar to African blacks but in this
study, bacterial and viral infections and scabies are also more
common. The explanation of this significantly less frequent
infection rate in Africans may be the existence of some naturally
32
Household and Personal Care TODAY - n 3/2010
Table 3. Composition of various Infective disease categories.
HAIR RELATED DISORDERS
Traction alopecia in females and pseudofolliculitis in males are the
commonest hair related disorders seen in Africans (Figures 3 and
4ù). There are some structural hair differences in black African; for
instance, the curvature of the hair follicle and the configuration of
the actual hair of many blacks are the biologic attributes that
appear to have a direct influence on the development of
pseudofolliculitis barbae in Africans (24). Curved hair forms an arc
in the dermis and is almost parallel to the skin surface. After these
facial hairs are cut, a few millimetres of growth will cause them to
puncture the skin, resulting in extra follicular penetration and
followed by a neutrophil-mediated inflammatory response (6, 24).
The growing of beards in black men is mostly to avoid these
detrimental consequences of shaving, and can redress a
potential hair follicle disorder. Traction alopecia, occurring
primarily at the frontal and temporal hairline, is well recognized
and is related to tension on the hair. In blacks, fewer elastic fibres
anchor hair follicles to the dermis compared with white persons
(6). This biologic feature, combined with cultural practices of tight
braids and ponytails, may impact on the development of traction
alopecia and weighty artificial hair attached to hair weaves and
braid extensions have further additional affect. Hot-comb
alopecia, follicular degeneration syndrome, or centrifugal scarring
alopecia, in African women is another common form of traction
alopecia that occurs in the vertex and midscalp. This presents
clinically with a decrease or absence of follicular openings and a
shiny appearance of the scalp. The cause of this alopecia still
remains an enigma and clinically, it differs from traction alopecia in location on the
scalp as well as pattern and appearance (6, 24, 25).
ACNE/FOLLICULITIS
Acne is one of the most common skin problems seen in ethnic skin (Figure 3ù). There is
significant clinical and histopathological difference seen in acne vulgaris in darker skin
when compared with Caucasian skin. This may explain why acne in darker skin
frequently results in formation of postinflammatoru hyperpigmented macules (26).
Mostly, the disease tend to be mild clinically and incidence of severe form like
nodulocystic acne is lower in Africans (27). Hair pomades and conditioners are also
popular in African blacks. These containing various mixtures of petrolatum, lanolin, and
vegetable, mineral, or animal oils may produce “pomade acne”; an eruption,
consisting mainly of comedones on the forehead and temporal area. Pomades also
can contribute to scalp folliculitis and hair loss (26, 27).
KELOIDS/HYPERTROPHIC SCARS
Scars and keloids are frequently seen in black Africans which can be post traumatic,
idiopathic or may be the outcome of certain cultural practices (Figure 4ù). Scarification
is a common cultural practice in many African societies where cuts are made for
beautification as well as ritual purposes. Linear scars are produced by deep cuts with a
sharp instrument which desirably results in keloid formation (28). Scarification is carried
out during multiple procedures at different ages throughout childhood and especially
at puberty. These ritual scars are thought to enforce group affiliation and promote tribal
integration. The marks vary from tribe to tribe and can include both facial markings and
body markings and earlobe stretching. They may be used for decorative purposes on
the faces, for tribal identification or for medicinal purposes. Although keloidal scarring
occurs in all races, it is thought to occur much more frequently in black persons ranging
from 3 to 18 times more often in black persons compared with white persons (5, 28, 29).
This scarring is thought to develop through a complex interaction between fibroblasts,
mast cells, and cytokines that facilitates the production of excessive collagen and
inhibits the degradation of the extra cellular matrix components (5). Biologically the
fibroblasts are larger, numerous and multinucleated in black persons and possibly await
just a trivial stimulus to start the overproduction of collagen that is provided culturally
through iatrogenic cuts, abrasions or burns (5, 6).
ECZEMATOUS DISORDERS
In certain ethnic populations, eczema is seen second most common disorders after
acne vulgaris but incidence of eczematous disorders observed in black Africans of sierra
Leone was not much different from that of Asian population. Common eczematous
disorders include; atopic dermatitis, seborrhoic dermatitis, contact dermatitis and
pityriasis alba (14, 18).
PIGMENTARY SKIN DISORDERS
Skin pigmentation and dyschromias are often key skin concerns for patients of colour
(Figure 5ù )(11, 30). Although melanin confers a protection from UV radiation,
pigmented skin can also experience significant photodamage, manifested by
epidermal atypia and atrophy, dermal collagen and elastin damage, and marked
hyperpigmentation (30, 31). Pigmentary disorders are seen 3rd or 4th most frequent
disorders in black Africans (39). The actual pathogeneses of postinflammatory
hyperpigmentation and hypopigmentation remain unknown. However, normal
biologic phenomena, specifically the release of inflammatory mediators and cytokines
from inflammatory cells, as well as epidermal cells and melanocytes, most likely play a
role (31). Leukotriene B4, prostaglandins D2 and E2, endothelins, interleukins 1 and 6,
and tumour necrosis factor-a have been observed to increase melanogenesis. A
decrease in melanogenesis has been reported to be caused by leukotriene C4.
Particular cytokines and leukotrienes, such as leukotriene C4 and transforming growth
factor-a, cause movement of melanocytes (31, 32). Postinflammatory
hypopigmentation is another common complication seen in ethnic skin from numerous
inflammatory diseases like seborrheic dermatitis and pityriasis alba (15). Melasma is also
common especially in females (11). Although the exact cause of melasma is unknown,
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Table 4. Various cultural practices and subsequent skin disorders.
many factors have been linked to its pathogenesis, such as
genetics, UV radiation exposure, pregnancy, hormonal
treatments, cosmetics, and phototoxic and anti-seizure
medications. Vitiligo in the form of well-circumscribed
depigmented macules causes significant cosmetic and
psychologic concerns in darker-skinned individuals (33). The
prevalence of pigmentation disorders in black subjects has
resulted in their use of many topical products that are not always
prescribed or monitored by physicians. These cultural practices
can result in further pigmentary disorders (hyper pigmentation or
hypopigmentation) (11, 15). Some of the pigmentary disorders;
like body tattooing, genital tattooing, female genital
pigmentation (post circumcisional), post medicinal pigmentation
and carotenemia are possibly the result of social and cultural
taboos, rituals, and dietary habits (15, 34, 35) Some physiological
pigmentary land marks like pigmentary demarcation lines and
linea nigra along with peculiar dermatosis called dermatosis
papulosa nigra are also seen in blacks (30).
SKIN DISORDERS RELATED TO ETHNIC/CULTURAL PRACTICES
A variety of cultural practices are observed in different ethnic
groups throughout the world (Figure 6ù). Few of such practices in
African blacks include; various hair grooming techniques (as a
cause of traction alopecia), especially designed cut marks on
face, arms or back (cause of scar and keloid formation) for tribal
identification and use of pomade (cause of pomade acne). Post
inflammatory hyper and hypopigmentatinon and scar formation
is also observed secondary to coin rubbing, cupping, moxibustion
and female circumcision (33, 35, 36). Skin dyspigmentation
(Postinflammatory hyperpigmentation or hypopigmentatinon)
can frequently be the outcome of certain prevailingcultural rituals
and overuse/misuse of some traditional cosmetic products
containing hydroquinone and potent topical steroids (36, 37). Hair
pomades and conditioners containing various mixtures of
petrolatum, lanolin, and vegetable, mineral, or animal oils may
produce “pomade acne”; an eruption, consisting mainly of
comedones on the forehead and temporal area (27). Table 4 lists
some cultural practices and their consequent skin disorders.
LESS COMMON SKIN DISORDERS
Table 5 lists some dermatological disorders which do occur in
black Africans but there is no special ethnic predilection (see also
Figure 3ù).
34
Household and Personal Care TODAY - n 3/2010
Table 5. Composition of various less common disease categories.
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