- M/C depigmenting skin disorder
Vitiligo is the commonest cause of depigmentation. It can appear at any age from child to adulthood but peak incidence is reported in the second and third decade. The age of onset usually varies between the sexes. Its prevalence is approximately 0.1-2% of people including adults and children worldwide and it affects all races equally.
The exact etiology of vitiligo is unknown. It is frequently associated with multiple autoimmune diseases. There are various theories about its pathogenesis and the etiology is multifactorial. It is characterized by incomplete penetrance, genetic heterogeneity, and multiple susceptibility loci. Family and other twin studies have shown that inheritance is complex and also involves both environmental and genetic factors. Additionally, it is hypothesized that genetic factors can influence the age of onset of vitiligo. The inheritance of vitiligo may also include genes associated with the biosynthesis of melanin, regulation of autoantibodies, and response to oxidative stress.
- Neural hypothesis: Neurochemical mediator destroys melanocytes and decreases production of melanin
- Oxidative stress hypothesis: Oxidant and anti-oxidant mechanism intermediate or metabolic product of melanin synthesis causes destruction of melanocytes
- Genetic theory: Intrinsic defect of melanocyte results in an inherent abnormality that impedes their growth and differentiation
- Autoimmune/cytotoxic hypothesis: Alteration in humoral and cellular immunity causes destruction/dysfunction of melanocytes
Autoimmune/cytotoxic hypothesisThis theory supports the hypothesis that nonsegmental vitiligo is commonly associated with autoimmune disorders than the segmental type of vitiligo.
- Autoimmune thyroid disease (M/C)
- Type 1 diabetes
- Pernicious anemia
- Rheumatoid arthritis
- Systemic lupus erythematosus (SLE)
- Addison disease
Vitiligo presents clinically with signs and symptoms of white spots on the body distributed symmetrically and more obvious in people with dark skin. The lesions are characterized by well-demarcated pearly white or depigmented macules and patches, oval, round, or linear-shaped, and the borders are convex, range from the size of few millimeters to centimeters and enlarge centrifugally.
The severity of the disease is scored by the body surface area affected. The course of the disease is often unpredictable and varies in response to the treatment.
Bordeaux Vitiligo Global Issues Consensus Conference (VGICC) classification:
|Non-segmental vitiligo (NSV)||Acrofacial|
|Mucosal (more than one mucosal site)|
|Mixed (associated with SV)|
|Segmental Vitiligo||Uni-, bi-, or plurisegmental|
|Mucosal (one site in isolation)|
Non-segmental vitiligo( NSV):Characterized by depigmented macules that vary in size from a few to several centimeters in diameter, often involving both sides of the body with tendency toward symmetrical distribution
- Acrofacial: Only extremities and/or face involved
- Mucosal: Oral and genital mucosae
- Generalized/common: Symmetric, bilateral, depigmented macules in a random distribution over the entire body surface
- Universal (M/C form in adulthood): Affects largest extent of tegument (80-90% body surface). The generalized or common form usually precedes it
- Mixed: Concomitant involvement of segmental and non-segmental vitiligo. Most often, the segmental form precedes NSV.
- Rare forms: vitiligo punctata, minor and follicular. These types were also considered unclassifiable.
Segmental VitiligoUnilateral, asymmetric distribution of white macules that match a cutaneous segment (dermatomal distribution) usually respecting the body midline, and there is also involvement of body hair (leukotrichia) besides rapid onset of the condition.
- Mono/unisegmental (M/C form)
Koebner’s phenomenon “isomorphic response”:Development of lesions at sites of specifically traumatized uninvolved skin of patients with cutaneous diseases
Complications of vitiligo are social stigmatization and mental stress, eye involvement like iritis, depigmented skin is more prone to sunburn, skin cancer, and hearing loss because of loss of cochlear melanocytes. Other complications are related to medications like skin atrophy after prolonged use of topical steroids.
The diagnosis of vitiligo is usually made on clinical features . The severity of the disease is scored by the body surface area affected. The course of the disease is often unpredictable and varies in response to the treatment.
Wood lamp examination:Differentiate vitiligo from other hypopigmented or depigmented disorders
Skin biopsy:The histopathological examination of the skin reveals the absence of melanocytes and complete epidermal pigmentation loss. Superficial perifollicular and perivascular lymphocytic infiltrates may be present at the margin of the vitiligo lesions, due to the cell-mediated process that destroys the melanocytes.
Differential diagnosis:Differentiate vitiligo from other hypopigmented or depigmented disorders.
Various types of topical and systemic medications, phototherapy, laser therapy, and surgical therapy are used for the treatment of vitiligo.
Topical treatments:First-line vitiligo treatment includes moderate-to-high strength topical corticosteroids and calcineurin inhibitors, both of which dampen the cellular immune response
Systemic medications:Systemic corticosteroids are generally employed in rapidly progressive cases to help with disease stabilization.
It is a chronic skin condition with an unpredictable disease course and some patients may notice spontaneous repigmentation over the depigmented areas. The prognosis depends upon the age of onset and the extent of disease. Early disease onset is usually associated with the involvement of greater body surface area and rate of progression. Few types and certain locations may be responsive to treatment. Refractory cases have been noted in patients presenting with segmental vitiligo and younger than 14 years of age. Most of the patients on treatment usually experience intermittent cycles of pigment loss and disease stabilization.