PIGMENTATION
- What is the basic structure of the skin and what is responsible
for giving it a color ?
- Skin is the largest organ of the body. It is made up of two layers, the
upper 'epidermis' and the lower 'dermis'. The epidermis and the dermis are
further divided into other layers.
The lower most layer of the epidermis
is known as the basal layer and it contains organelles called 'melanosomes'.
These melanosomes contain cells called melanocytes which produce a pigment
called 'melanin'. The color of skin depends mainly on this melanin and the
amount of melanin present in the other layers of the epidermis. The
thickness of epidermis and vascularity of the epidermis are other factors
affecting the color of skin.
- What are the causes of hypo pigmentation (decrease in
skin pigmentation) ?
- Pityriasis alba
: Hypo pigmented patch may be seen on the face usually
in young children. It is common in winter and in those with history of
atopy. It can be treated with a mild topical steroid.
- Pityriasis versicolor :
It is a superficial fungal infection caused by
a yeast 'pityrosporum orbiculare'.
Well defined hypo or hyper pigmented lesions with fine scales are found
on the chest, back, neck and sometimes on the face. It is treated with
topical and oral anti fungal drugs.
- Leprosy : It is a chronic disease caused by 'mycobacterium leprae'
and affects mainly the skin and nerves.
A hypo pigmented patch with absent or decreased sensation is seen in
tuberculoid type of leprosy (good immune response) whereas in lepromatous
type (low immune response) the sensations may be normal. It can be
cured with the help of drugs.
- Vitiligo : This is an autoimmune diseases
where de pigmented patches are
seen, they may occur any where on the body. The treatment is detailed
in the chapter on vitiligo.
- secondary leucoderma : This occurs due to contact
with certain chemicals
phenol derivatives, glue of 'bindi', rubber slippers, plastic watch
straps,
photograph developing solutions or burns.
It can be treated by spot dermabrasion
or
skin grafting.
- Post inflammatory hypo pigmentation : It occurs after the
healing phase of
certain dermatoses such as eczemas, psoriasis, candidiasis etc.
- Nevus depigmentosus : It is a congenital, well defined,
hypo pigmented patch
present since birth. It can be treated by spot dermabrasion or
ablation with Co2 laser followed by ultra thin skin grafting.
- What are the causes of hyper pigmentation (increase in
skin pigmentation) ?
- Hyper pigmentation may either be due to increased melanin deposition in the epidermis
or dermis.
Epidermal pigmentary disorders respond well to treatment while dermal pigmentation
may take a long time to lighten.
- Melasma :
Seen as brown patches on the face, it is more
commonly seen in females.
It occurs due to hormonal changes in the body. The pigmentation increases on sun
sun exposure.
- Peri-orbital melanosis :
Also known as 'dark circles'
may be heriditary, due to stress or eye strain
- Freckles and Lentigenes :
These are tiny black spots on
the face and are genetic in origin.
- Photomelanosis : This is increased pigmentation due
to sun exposure. The pigmentation occurs on exposed skin, commonly on the face, neck
and the back. The pigmentation may be patchy or as diffused darkening of the
exposed skin.
- Sun burn (tan) : A condition commonly encountered in fair skinned people
due to excessive sun exposure.
- Post inflammatory hyper pigmentation : It may be seen
in the following cases
- Seen after healing has occured, like in acne,
eczemas,
contact dermatitis etc.
- Drug induced pigmentation.
- Pigmentation due to cosmetics especially those containing fragrance.
- Macular lichen amyloidosis.
- Nevus or 'Birth mark' : Usually seen at birth
but may also appear at a later age.
- Tattoo : Tattoos are pigments inserted into the skin for
decorative purpose which may at times be a part of tradition. Usually these
artificial pigments are inserted deep into the dermis which makes them permanent
and stubborn.
- What is the treatment for hyper pigmented disorders ?
- Melasma, Photomelanosis and post inflammatory hyper pigmentation can
be treated with topical creams such as hydroxy quinone, tretinoin, topical steroids
,alpha hydroxy acid creams or azelic acid. If the patient does not improve with these medicines other
modalities should be used, which may be ;
- Chemical peeling
with tri-chloro acetic acid
or glycolic acid.
- Electrical stimulation of the skin.
- Iontophoresis.
- Intense pulse light treatment
- Laser surgery
- Peri-orbital melanosis : Spot glycolic acid peel
or electrical stimulation of the skin may be done. One may also
try intense pulse light therapy.
Iron supplements and anti oxidants help when taken orally.
- Freckles and lentigens : we have the following modalities
- Macular and lichen amyloidosis : We may use the following treatment
- Topical tretinoin or steroids
- Oral vitamin A, Etretinate or Colchicine may be taken
- Cryo-spray with liquid nitrogen
- Carbon dioxide laser treatment or treatment with Q switched NdYag
laser.
- Spot dermabrasion
in case of lichen amyloidosis
- Nevus can be removed by pigmented laser
- Tattoo may be removed by dermabrasion
or laser surgery
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