Vitiligo
From Standard of Care
Suggested to be an autoimmune disease associated with other autoimmune processes such as pernicious anemia, rheumatoid arthritis, psoriasis, alopecia areata, type I diabetes, Addison's disease, thyroid diseases and polyglandular autoimmune syndrome.
Results from loss of melanocytes.
Complex process that involves multile susceptibilty genes and unknown environmental factors.
The association with generalized vitiligo and autoimmune disease suggest shared genetic components.
In a genomewide association study of 579,146 single nucleotide polymorphisms in 1514 patients with generalized vitiligo of European descent: significant associations with generalized vitiligo and SNPs associated with other autoimmune diseases-PTPN22, LPP, ILRA, UBASH3A, RERE, and TYR.
The presence of TYR SNP appears to be mutually exclusive btween susceptibility to vitiligo and asuceptibility to melanoma.
Most common depigmenting disorder.
Prevalence worldwide is 0.5%.
Approximately 50% of patients present before the age of 20 years.
No gender difference and no racial or skin type differences.
Nonsegmental, or generalized disease, the most common form and accounts for 85-90% of cases.
Segmental form of the disease has an earlier onset, and may account for as much as 30% of childhood cases.
Both nonsegmental and segmental vitiligo can start out as focal abnormalities with small affected area of involvement of less than 15cm2.
Segmental and nonsegmental disease can rarely occur together.
When segmental and nonsegmental vitiligo occur together the segmental lesions are more difficult to treat.
Manifested as loss of epidermal melanocytes (Gauthier).
Completely depigmented areas have no inflammation.
At the margins of rapidly progressive depigmented disease, areas mononuclear cells may be present in nonsegmental lesions.
Cause of nonsegmental disease may involve immunologic factors, oxidative stress or sympathetic neurogenic disturbance.
In nonsegmental disease the upward migration of melanocytes 24 hours after mechanical trauma in perilesional areas indicates a cutaneous response to nonspecific trauma in the pathogenesis of the disease (Koebner‘s phenomenon).
In segmental disease a neurogenic sympathetic disturbance is suspected to contribute to the initiation of the process and a genetic anomaly may be related.
In segmental disease a neurogenic sympathetic disturbance is suspected to contribute to the initiation of the process and a genetic anomaly may be related.
Populations in Europe related to autoimmune diathesis and some genes.
Autoimmune related disease associated with gene encoding NACHT leucine-rich repeat protein-1 or NALP1 has been identified (Jin Y).
In nonsegmental disease macules have homogenous depigmentation with well defined borders.
Loss of hair pigmentation may occur in advanced disease.
After sun exposure the interface between the hypopigmentated and normal areas may become hyperpigmented.
In rapidly progressive disease patchy depigmentation may follow pinpoint depigmentation (Taieb A).
In segmental disease lesions have more irregular borders and less homogenous depigmentation than in nonsegmental vitiligo.
in individuals with dark skin the mucosa may be prominently involved.
Halo nevi are 8-10 times more common in such patients than in the general population.
Halo nevi that are multiple may be associated with cellular autoimmunity against nevi cells and may indicate higher risk of vitiligo among patients with a family history.
Some patients with nonsegmental disease vitiligo an accelerated phase may occur over weeks to months.
Thyroid functions should be measured annually in nonsegmental vitiligo as there is an increased risk of autoimmune thyroid disease, especially Hashimoto’s disease.
Association with autoimmune disease varies with the patient’s skin type and race.
