12/29/2023 0 Comments Vitiligo universalis definitionVitiligo can also be induced by drugs, such as immune checkpoint inhibitors ( pembrolizumab, nivolumab) and BRAF inhibitors ( vemurafenib, dabrafenib) used to treat metastatic melanoma. Other rare dermatologic syndromes that present with lesions indistinguishable from vitiligo are:Ī vitiligo-like leukoderma may occur in patients with metastatic melanoma. These syndromes affect organs that normally house melanocytes, and are now believed to constitute one disease entity with variable clinical expression. Vitiligo is also a component of some rare multiorgan syndromes, such as: Understanding the molecular pathogenesis of vitiligo serves as a promising source for the development of more targeted therapies. These TRM cells may be responsible for what is called an ‘autoimmune memory’, in which relapses occur mostly at the same exact site of previous lesions. Maintenance phase: established lesions are maintained by resident melanocyte reactive T-cells (TRM cells), through the IL15-dependent pathway. ![]() Of note, where both humoral ( antibody) and T-cell responses appear to be implicated, antibody titres do not correlate with disease activity nor the localisation of distinct vitiligo lesions. Acting together on their common CXCR3 receptor, CXCL9 drives the main bulk of CD8+ cell homing, while CXCL10 promotes their localisation to affected skin lesions and induction of melanocyte apoptosis through CXC3B activation.This will lead to the production of chemokines (CXC), predominantly by keratinocytes, but also by melanocytes themselves, leading to IFN-γ–CXCR3- CXCL9/10 axis loop feedback. CD8+ cytotoxic cells release cytokines, mainly interferon-γ (INF-γ) that activate the JAK-STAT pathway through its receptors on keratinocytes.Progression phase: an imbalance between ROS and antioxidants will activate the adaptive immune system bridged by the innate immune system.Initial phase: less adhesive melanocytes are prone to internal and external oxidative stresses, leading to the production of more toxic reactive oxygen species (ROS).This could be explained through three phases: The convergence or integrated theory combines immunological, biochemical, oxidative, and environmental mechanisms that work jointly in those with a genetic susceptibility is widely accepted. Many genetic loci have been identified, all related to the immune system, except for TYR which encodes tyrosinase, a key enzyme in melanin production and a major autoantigen in vitiligo. ![]() Genetic factors appear to contribute to 80% of vitiligo risk, whilst environmental factors account for 20%. Vitiligo is due to the loss or destruction of melanocytes ( melanin-producing cells). Vitiligo is also three times more common in recipients of allogeneic bone marrow and stem-cell transplants than in the healthy population. Other autoimmune dermatologic conditions, eg, psoriasis and lichen sclerosus.Insulin- dependent diabetes mellitus (mostly adult-onset).Other less frequently associated autoimmune disorders with vitiligo are:.The strongest association is with thyroid disease, which can affect up to 15% of adults and 5–10% of children with vitiligo.More than 20–30% of the affected individuals report vitiligo in a first or second-degree relative.Īutoimmune disease development has been associated with generalized vitiligo, the most common type of vitiligo, especially if there is a family history of vitiligo and other autoimmune disorders.Inheritance: follows a polygenic pattern, with a 23% monozygotic twin concordance, supporting the cause of vitiligo to be multifactorial ( genetic and non-genetic environmental factors).80% of all cases present before the age of 30.50% of non-segmental vitiligo cases start before the age of 20.41% of segmental vitiligo cases start before the age of 10.Typically, there are two peaks of onset, early (<10 years) or late (around 30 years). Onset: the average age of onset is between 20–24 years, but can occur at any age.Women tend to constitute a higher percentage of overall outpatient visits, due to greater concerns about cosmetic appearance.Sex: both men and women appear to be equally affected.More common in India (up to 8.8% of the population). ![]()
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