What is Vitiligo?
Vitiligo is a pigmentary skin disorder in which pigment cells (melanocytes) are destroyed, resulting in circumscribed depigmented (white) macules and patches on the skin.
Vitiligo affects about 0.5-2% of the world population, and the average age of onset is 20 years. Of those affected 6-38% has positive family history. Males and females are equally affected. People with autoimmune disorders like diabetes, thyroid disease, pernicious anemia (B12 deficiency), Addison's disease (adrenal gland disease) and alopecia areata are associated with Vitiligo.
What causes Vitiligo?
Vitiligo is caused by multiple factors including genetic and non-genetic factors. It is a result of the malfunction/destruction of melanocytes which produce the skin pigment melanin. The factors are:
1.Autoimmune: Autoantibodies produced act against the melanocytes antigens resulting in destruction of melanocytes. Autoimmune disorders like Thyroid disorders (Hashimoto thyroiditis and Graves disease), Addison disease, diabetes mellitus, alopecia areata, pernicious anemia, inflammatory bowel disease and psoriasis are all associated with Vitiligo.
2.Genetic: About 6-38% of affected patients have a positive family history of Vitiligo. It has been associated with recessive genes and Human leukocyte antigens (HLA-DR4, HLA-DQA1 and DQB1). The genes involved are associated with biosynthesis of melanin, oxidative stress (free radicals that are toxic to melanocytes and destroy them) and regulation of autoimmunity (antibodies against melanocytes).
3.Neural Theory: patients with a nerve injury have hypopigmentation or depigmentation (white patches) in denervated areas forming a form of Vitiligo called segmental Vitiligo.
4.Autocytotoxicity: There is a defective free-radical defense resulting melanocytes’ death as a result of free radicals’ toxic attack on the melanocytes (disturbance in oxidant-antioxidant system).
5.Intrinsic Defect: Patients with Vitiligo may have intrinsic defect in the melanocytes that led to the death of these cells.
Types of Vitiligo
Vitiligo is best classified into segmental and non-segmental Vitiligo.
1.Segmental Vitiligo: Age of onset is during childhood. In 90% of the cases it presents as one single patch affecting one side of the body. Very few patients have a second segment. The commonly affected sites are head and neck region, the trunk and extremities. The affected site will enlarge rapidly to the maximum size and seldom progress further. Segmental Vitiligo is seldom associated with autoimmune disorders.
2.Non-segmental Vitiligo: It can affect different proportions and areas of the body (Focal, generalized or universal) often following a symmetrical and bilateral in distribution. Acrofacial distribution is when white patches occurs on the distal fingers and peri-orificial (surrounding an orifice) areas.
Vulgaris distribution is characterized by scattered patches that are widely distributed. Mixed distribution is when Acrofacial and vulgaris vitiligo occur in combination or segmental and Acrofacial vitiligo and/or vulgaris involvement are combined.
Universal Vitiligo is complete or nearly complete depigmentation (whitening) often associated with multiple endocrine disorders.
Vitiligo present as white or hypopigmented macules or patches which can be oval, round or linear in shape. The borders may be ill defined in early stages, subsequently the borders are well demarcated. It can vary in size from millimeters to centimeters. Rate of growth is unpredictable.
It occurs most frequently on the hands, forearms, feet, scalp neck and face, favoring a perioral (around the mouth) and periocular (around the eyes) distribution. Vitiligo also involves mucosal area and occurs around body orifices such as the lips, genitals, gums and nipples.
Leukotrichia (body hair) involvement appears as a localized patch of white or gray hair. It can affect scalp hair, eyebrows, pubic hair, and axillary hair. Koebnerisation refers to occurrence on areas subjected to repeated trauma. It can also occur around a mole (halo nevus).
Vitiligo diagnosis is usually made by its typical clinical features. A Skin biopsy can be done to differentiate it from other hypo-pigmentarydisorders if diagnosis is in doubt.
Blood tests to rule out potential autoimmune diseases as ANA, Full Blood Count, and Thyroid function test is not indicated unless supported by clinical suspicions.
Photographs to document clinical progression of vitiligo will be helpful.
Treatment of vitiligo
No single therapy produces predictably good results in patients and the response to each therapy is variable. Treatment must be individualized and customized to each patient.
General measures include sunscreen to protect the skin from sunburn and to avoid trauma induced vitiligo (Koebnerisation). Cosmetics and skin dyes can be used as camouflage cover for the white patches.
1.Topical steroids: useful for localized vitiligo. Potent steroids (betnovate and mometasone) and very potent steroids (clobetasol propionate) have high success rates of about 55%. If improvements is seen, it can be continued but watch out for symptoms like skin atrophy and telangiectasia (dilatation of blood vessels). If no response after 3 months of treatment, other treatment modality should be tried.
2.Topical Tacrolimus (Protopic): It acts as an immune-modulator and does not cause skin atrophy and other side effects of steroids. It should be considered for head and neck areas of vitiligo especially on the eyelids.
3.Topical Pimecrolimus: It is especially useful for facial lesions and does not have side effects of steroids.
4. Topical calcipotriol: are Vitamin D analogues that target the local immune response and act on specific T-cell activation. They have been found to be effective in some patients.
1.Narrow Band UVB phototherapy has the best successful rates (63%) compared to other wavelength phototherapy. Treatment is given about 2-3 times a week but never on consecutive days. If no visible repigmentation after 30 sessions than alternative therapy should be considered. To achieve complete repigmentation, about 100-200 treatments may be necessary. It is safe for children, pregnant women and lactating women.
2.Topical PUVA and Psolarens whereby psolarens like Methoxsalen (8-MOP, Oxsoralen) are applied on affected skin before UVA phototherapy.
3.Systemic PUVA is only considered if patients have large body surface area (>20%) involved and those who have failed topical steroid/immune-modulator therapy. It is contraindicated in children, lactating women, pregnant women and those who have photosensitivity disorders. Oral 8-MOP is started at 0.3mg/kg, given 2 hours before shinning with UVA light therapy. The dose is slowly increased after each treatment. Side effects include nausea, vomiting and phototoxic reactions.
Excimer laser: produces monochromatic rays at 308 nm to treat limited single stable patches of vitiligo. It is a safe, well tolerated, effective procedure however it is expensive. Patients are treated twice weekly for an average of 24-48 sessions. According to some study, patients have 75% repigmentation after 32 treatments.
Surgical skin grafting
Surgical skin grafting may be considered for those above 12 years old with Stable vitiligo (no new lesions or increase in size of old lesions for past 2 years, absence of Koebnerisation and presence of spontaneous repigmentation) and no history of keloid (thickened scar) formation.
Skin grafts from another part of the body to be transferred to affected site include suction epidermal grafts, split skin thickness grafts, cultured epidermal / melanocyte suspensions and mini-grafts. The success rates of skin grafts can be as high as approximately 87%.
If a darker-skinned person has generalized vitiligo, he may want to consider depigmentation therapy. It involves the application of 20% monobenzylether of hydroquinone cream up to twice daily for 9 to 12 months until the skin is bleached. Side effects include local itchiness, redness and possible contact dermatitis. The result is irreversible so the patient must be very sure of his decision before proceeding with it.