Hypopigmentation disorders
Localized or generalized
Congenital/hereditary or acquired
Circumscribed, diffuse, linear or
reticulated
Hypopigmented skin: The only
feature, the main feature, or part of a
syndrome with other clinical
manifestations
Pigment cell biology
Melanocytes: Pigment-producing dendritic cells of the skin,
originated from the neural crest from where they migrate
during embryogenesis; located mainly in the basal layer of
the epidermis and the matrix of the hair follicle
Melanosomes: Specific organelles in the cytoplasm of the
melanocytes, where melanin is deposited
As the melanosomes mature and acquire melanin, they
move to a perinuclear position into the dendrites.
Each melanocyte interconnects with 36 keratinocytes.
These surronding keratinocytes phagocytize the tips of the
melanosome-containing dendrites and transfer the
pigment!!→→ normal skin pigmentation
Leukoderma and Hypopigmentation
Defects in the number or function of
melanocytes
Decrease melanization of
melanosomes
Decrease of the transfer process from
melanocytes to keratinocytes
VİTİLİGO
Vitiligo is characterized clinically by
development of totally white macules,
microscopically by complete absence of
melanocytes.
Epidemiology
Sex: Equal in both sexes.
Age of onset: At any age, but in 50%
between the ages of 10 and 30 yeras.
A few cases at birth.
Race:All races.
Inheritance: Polygenic. > 30% have
reported vitiligo in a parent, sibling or
a child.
Pathogenesis
The autoimmune theory
The neurogenic hypothesis
The self-destruct hypotesis
History
After a -physical trauma ( Koebner),
illness or emotional stress.
After the death of a relative or after
severe physical injury
After a sunburn reaction
Physical examination
“Chalk” or pale white, sharply marginated
macules, 5 mm to 5 cm or more in diameter
Focal type, segmental type, generalized
Around the eyes, mouth, digits, elbows, knees, low
back, genital areas
Associated cutaneous findings: White hair
(poliosis), prematurely gray hair, alopecia areata,
halo nevi.
General examination: Up to 30% of cases
associated with thyroid disease (Hashimoto
thyroiditis, Graves’ disease); diabeytes mellitus (<
5%); pernicious anemia; Addison’disease(
uncommon), MEN (rare).
Differential diagnosis (1)
Oculocutaneous albinism
Fenilketonüri, homosistinüri, histidinemi (AR)
Selenium and copper deficiency
Pityriasis alba
Pityriasis versicolor
Chemical leukoderma (phenolic germicides)
Leprosy
Nevus depigmentosus (congenital, nonprogressif,
stable in size, normal or decreased number of
melanocytesdecrease in the synthesis and
transfer of melanosomes, trunk, proximal
extremities, isolated, segmental or systematized (
unilateral whorls and streaks)
Nevus anemicus
Secondary syphilis
Differential diagnosis (2)
Waardenburg’s syndrome (commonest cause of congenital
sensorineural deafness, poliosis, white macules and white
forlock, iris heterochromia, dystopia canthorum, broad nasal
root, limb defects, Hirschprung disease)
Tuberous sclerosis (multiple hypomelanotic macules, “ash
leaf”, decreased number of melanosomes…. Decreased
epidermal melanin, facial angiofibromas, periungual
fibromas, CNS, retinal astrocytomas, cardiac rabdomyomas,
dental enamel pits, hepatic, renal hamartoma, lung
involvement)
Piebaldism: congenital, complete absence of melanin and
melanocytes or a reduced density, remain stable throughout
life, white forelock, poliosis of the eyebrows and eyelashes,
premature graying of the scalp hair, hyperpigmented
macules in normal skin and within the areas of leukoderma,
anterior trunk, mid extremities, mid forehead, frontal scalp,
do auditory testing! (Woolf sndrome, WS), no treatment,
sunscreens, minigrafts transplantation of uninvolved skin
Differential diagnosis (3)
Post-inflammatory leukoderma
Menkes syndrome (X-linked recessif, inappropriate
intracellular copper storage, pili torti,CNS involvement)
Hypopigmented Mycosis Fungoides
Vogt-Koyanagi-Harada Syndrome ( uveitis, vision problems,
photophobia, bilateral dysacusia, CNS involvement,
sensorineural hearing loss)
Hypomelanosis of ITO: normal or decreased number of
melanocytes and melanosomes, decreased melanin ,
neurocutaneous syndrome, whorled and streaked, linear
lesions following the lines of Blaschko, trunk and extremities,
at birth, during infancy or childhood, alopecia, teeth
alterations, neurologic, musculuskletal, cardiac and ocular
abnormalities
Course and prognosis
Chronic disease
The course is highly variable.
Up to 30%, spontaneous
repigmentation in a few areas.
Therapy
Sunscreens
Cosmetic coverup
Repigmentation: Topical
glucocorticoids, topical
photochemotherapy, systemic
photochemotherapy, narrow-band
UVB, tacrolimus, pimecrolimus
Minigrafting
Depigmentation