Difference in Pathogenesis Between Vitiligo Vulgaris and Halo Nevi Associated with Vitiligo is Supported by an HLA Association Study

Melanocytes and keratinocytes morphological changes in vitiligo patients. A histological, immunohistochemical and ultrastructural analysis

Vitiligo is an idiopathic acquired chronic stigmatizing disease. It is a pigmentary disorder that affects the skin and the mucous membranes, and it is characterized by well-circumscribed, depigmented milky white macules and patches. It has an estimated prevalence of 0.5-2% of the population worldwide. In the previous studies, several mechanisms such as autoimmune, oxidative stress, genetic factors, melanocytorrhagy, and neural hypothesis have been suggested for vitiligo pathogenesis.We aimed to assess the morphological changes of epidermal melanocytes and keratinocytes in patients with vitiligo. This aim will be fulfilled by histological, ultrastructural, and immunohistochemical analysis of skin biopsies from lesioned and non-lesioned sites in vitiligo patients.The study was carried out on 15 selected patients with stable vitiligo vulgaris but not receiving treatment in the last year and they fulfilled our inclusion criteria.Biopsies were taken from lesioned and non-lesioned sites in the same vitiligo patients, and they are processed for examinations by LM (using Hx & E, and Masson Fontana stain), immunohistochemical analysis (using Melan-A, E-cadherin, and caspase-3), and TEM (to demonstrate the ultra-structures).By LM, staining with Hx & E, lesioned skin in vitiligo patients showed hyperkeratosis, basal vacuolization, acanthosis with an increase in the epidermal thickness, ballooning of keratinocytes, and spongiosis. Regarding melanocytes, we observed a few numbers of melanocytes, also we detected some basal epidermal cells contain brown melanin granules. Using Fontana-Masson stain, we found that the melanin pigment is present in both lesioned and non-lesioned skin of vitiligo patients. We confirmed the presence of melanocytes in the lesioned skin by the immunohistochemical staining with Melan-A. The epidermal cells in lesioned skin of vitiligo patients showed weak positive expression of E-cadherin between them and an increase in the number of apoptotic Caspase-3 positive cells. BY TEM, the lesioned skin in vitiligo patients showed that the keratinocytes and melanocytes had various degenerative changes, disturbance of desmosomes in between keratinocytes, and absence of melanosomes in the keratinocytes. The detected melanocytes were degenerated and contained some melanosomes, melanin granules, and autophagosomes.We concluded that vitiligo pathogenesis is a combination of several factors and cannot be explained by only one mechanism. The pathology in the lesioned vitiliginous skin is a combination of several degenerative changes in keratinocytes, and melanocytes.

The Immunogenetics of Vitiligo: An Approach Toward Revealing the Secret of Depigmentation

Vitiligo is a hypomelanotic skin disease and considered to be of autoimmune origin due to breaching of immunological self-tolerance, resulting in inappropriate immune responses against melanocytes. The development of vitiligo includes a strong heritable component. Different strategies ranging from linkage studies to genome-wide association studies are used to explore the genetic factors responsible for the disease. Several vitiligo loci containing the respective genes have been identified which contribute to vitiligo and genetic variants for some of the genes are still unknown. These genes include mainly the proteins that play a role in immune regulation and a few other genes important for apoptosis and regulation of melanocyte functions. Despite the available data on genetic variants and risk alleles which influence the biological processes, only few immunological pathways have been found responsible for all ranges of severity and clinical manifestations of vitiligo. However, studies have concluded that vitiligo is of autoimmune origin and manifests due to complex interactions in immune components and their inappropriate response toward melanocytes. The genes involved in the immune regulation and processing the melanocytes antigen and its presentation can serve as effective immune-therapeutics that can target specific immunological pathways involved in vitiligo. This chapter highlights those immune-regulatory genes involved in vitiligo susceptibility and loci identified to date and their implications in vitiligo pathogenesis.

Transcriptome Analysis Reveals the Molecular Immunological Characteristics of Lesions in Patients with Halo Nevi When Compared to Stable Vitiligo, Normal Nevocytic Nevi and Cutaneous Melanoma

Background

Given their similar appearance and histology, halo nevi (HN) were considered as a type of vitiligo. However, whether HN have stronger immune response than stable vitiligo (VL) remains unclear. In addition, the molecular alterations in HN compared with normal nevocytic nevi (NN) and primary cutaneous melanoma (MM) must be determined. This study aimed to systematically characterize the molecular immunological features of HN.

Methods

Skin samples from patients with HN, VL, NN, and MM were obtained with informed consent. Each of the four groups underwent transcriptome sequencing and data analysis were for pairwise comparison. Quantitative real-time PCR (RT-qPCR) was conducted to confirm the transcriptional expression of some differentially expressed genes (DEGs) that were closely related to immunity.

Results

A total of 441 and 1507 DEGs were found in the HN/NN and HN/MM groups, respectively. Compared with those of VL, HN lesions contained 162 up-regulated DEGs and 12 down-regulated DEGs. Bioinformatics analysis showed that the up-regulated genes in HN were substantially enriched in immune response, immune deficiency, and immune rejection; biological stimulation (virus, bacteria); and proliferation and activation of immune cells. Immune cell composition analysis also confirmed high expression levels of multiple immunocytes in HN.

Conclusion

The molecular immune mechanisms of HN and VL were similar, but the immune activity of HN was stronger than that of VL. Innate and adaptive immunity were involved in the pathogenesis and progression of HN and VL.

Four-color Halo Congenital Nevus

Halo nevus (HN), also termed leukoderma acquisitum centrifugum or Sutton nevi, typically consists of central nevomelanocytic nevi surrounded depigmented zone resembling halo. The halo phenomenon can also occur around neurofibroma basal cell carcinomas, or malignant melanoma. Here we present a case of four-color halo nevus presented with a pink papule successively surrounded by a depigmented and a hypopigmented halo on a brown background. The four-color halo congenital nevus is an unusual form of Halo Nevus, which reflect the underlying mechanism of halo phenomenon that may be related with the immunity to the central nevus and different degrees of damage of melanocytes.

Factors Associated with Development of Vitiligo in Patients with Halo Nevus

Background:

Halo nevus (HN) has been shown to be associated with vitiligo, but no standard signs are currently available to identify HN patients at risk of vitiligo, and the relevant data obtained in previous studies are somewhat conflicting. This study aimed to identify factors affecting the presence of vitiligo in HN patients.

Methods:

We performed a retrospective study on consecutive patients with HN at the First Affiliated Hospital of Sun Yat-sen University between January 2011 and December 2016. Detailed demographic and clinical data were collected to identify the factors associated with the presence of vitiligo in this cohort of patients using uni- and multi-variate logistic regression analyses.

Results:

A total of 212 HN patients were included, 101 of whom had vitiligo-associated HN (HNV). Univariate analysis indicated that a personal history of thyroid diseases was positively associated with HNV (odds ratio [OR] = 10.761, P = 0.025), while the onset age of HN was negatively associated with HNV (OR = 0.537, P = 0.026). Multivariate analysis demonstrated that the Koebner phenomenon (KP; OR = 10.632, P < 0.0001), multiple HN (OR = 3.918, P < 0.0001), and a familial history of vitiligo (OR = 3.222, P = 0.014) were independent factors associated with HNV.

Conclusions:

HN without vitiligo has clinical features distinct from HN associated with vitiligo. HN patients with KP, multiple lesions, or familial history of vitiligo are more likely to develop vitiligo and therefore should be monitored for clinical signs of such accompanied conditions.

A similar local immune and oxidative stress phenotype in vitiligo and halo nevus

BACKGROUND

Vitiligo and halo nevus are two common T-cell-mediated skin disorders. Although autoimmunity has been suggested to be involved in both diseases, the relationship between vitiligo and halo nevus is not fully understood.

OBJECTIVE

The aim of the current study was to investigate whether vitiligo and halo nevus share the same immunological and oxidative stress response.

METHODS

Infiltrations of T cells, and expressions of chemokine receptors (CXCR3, CCR4, CCR5) and cytotoxic markers (Granzyme B, Perforin) in the lesions of vitiligo and halo nevus were examined by immunohistochemistry. Enzyme-linked immunosorbent assay was performed to analyze the expressions of chemokines in the serum samples and cytotoxic markers secreted by CD8⁺ T cells which were sorted from the peripheral blood mononuclear cells in healthy donors, vitiligo and halo nevus patients. Tissue levels of chemokine receptors and CXCR3 ligands in healthy controls, vitiligo patients and halo nevus patients were determined by qRT-PCR analysis. The percentages of CXCR3⁺ CD4⁺ T and CXCR3⁺ CD8⁺ T cells from the peripheral blood samples were examined by flow cytometry. Tissue and serum hydrogen peroxide (H₂O₂) concentrations were measured using H₂O₂ assay kit.

RESULTS

Immunohistochemistry revealed a significant T-cell response, with pronounced dermal infiltrates of CD8⁺ T cells in vitiligo and halo nevus. The inflammatory cytotoxic markers such as Granzyme B and Perforin were also elevated in vitiligo and halo nevus, suggesting inflammatory responses in situ. By qRT-PCR and ELISA assay, we found significantly increased expressions of the chemokine receptor CXCR3 and its ligands, especially the accumulated CXCL10 in the skin lesions of vitiligo and halo nevus. Moreover, the level of H₂O₂, a key player involved in regulation of the immune response was significantly upregulated in the skin lesions of vitiligo and halo nevus. In addition, the increased H₂O₂ concentration correlated positively with CXCL10 level in skin lesions of vitiligo and halo nevus.

CONCLUSIONS

These results demonstrate a H₂O₂-involved autoimmune phenotype in vitiligo and halo nevus, characterized by increased level of IFN-γ-inducible chemokine pair CXCL10-CXCR3, as well as a dense CD8⁺ T infiltration in the skin lesions, thus suggesting a similar pathogenesis of the two diseases.

A case-control study on association of proteasome subunit beta 8 (PSMB8) and transporter associated with antigen processing 1 (TAP1) polymorphisms and their transcript levels in vitiligo from Gujarat

BACKGROUND

Autoimmunity has been implicated in the destruction of melanocytes from vitiligo skin. Major histocompatibility complex (MHC) class-II linked genes proteasome subunit beta 8 (PSMB8) and transporter associated with antigen processing 1 (TAP1), involved in antigen processing and presentation have been reported to be associated with several autoimmune diseases including vitiligo.

OBJECTIVES

To explore PSMB8 rs2071464 and TAP1 rs1135216 single nucleotide polymorphisms and to estimate the expression of PSMB8 and TAP1 in patients with vitiligo and unaffected controls from Gujarat.

METHODS

PSMB8 rs2071464 polymorphism was genotyped using polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) and TAP1 rs1135216 polymorphism was genotyped by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) in 378 patients with vitiligo and 509 controls. Transcript levels of PSMB8 and TAP1 were measured in the PBMCs of 91 patients and 96 controls by using qPCR. Protein levels of PSMB8 were also determined by Western blot analysis.

RESULTS

The frequency of 'TT' genotype of PSMB8 polymorphism was significantly lowered in patients with generalized and active vitiligo (p = 0.019 and p = 0.005) as compared to controls suggesting its association with the activity of the disease. However, TAP1 polymorphism was not associated with vitiligo susceptibility. A significant decrease in expression of PSMB8 at both transcript level (p = 0.002) as well as protein level (p = 0.0460) was observed in vitiligo patients as compared to controls. No significant difference was observed between patients and controls for TAP1 transcripts (p = 0.553). Interestingly, individuals with the susceptible CC genotype of PSMB8 polymorphism showed significantly reduced PSMB8 transcript level as compared to that of CT and TT genotypes (p = 0.009 and p = 0.003 respectively).

CONCLUSIONS

PSMB8 rs2071464 was associated with generalized and active vitiligo from Gujarat whereas TAP1 rs1135216 showed no association. The down-regulation of PSMB8 in patients with risk genotype 'CC' advocates the vital role of PSMB8 in the autoimmune basis of vitiligo.

Dysfunction of Autophagy: A Possible Mechanism Involved in the Pathogenesis of Vitiligo by Breaking the Redox Balance of Melanocytes

Vitiligo is a common chronic acquired pigmentation disorder characterized by loss of functional melanocytes from the epidermis and follicular reservoir. Among multiple hypotheses which have been proposed in the pathogenesis of vitiligo, autoimmunity and oxidative stress-mediated toxicity in melanocytes remain most widely accepted. Macroautophagy is a lysosome-dependent degradation pathway which widely exists in eukaryotic cells. Autophagy participates in the oxidative stress response in many cells, which plays a protective role in preventing damage caused by oxidative stress. Recent studies have enrolled autophagy as an important regulator in limiting damage caused by UV light and lipid oxidation, keeping oxidative stress in a steady state in epidermal keratinocytes and maintaining normal proliferation and aging of melanocytes. Impairment of autophagy might disrupt the antioxidant defense system which renders melanocytes to oxidative insults. These findings provide supportive evidence to explore new ideas of the pathogenesis of vitiligo and other pigmentation disorders.

Dermpath quiz: An irregularly colored papule on the back of an adolescent female

This learning exercise challenges clinicians and dermatopathologists to consider the differential diagnosis of an unevenly colored solitary papule over the upper back of an adolescent female.

Comparison of Childhood Vitiligo Presenting with or without Associated Halo Nevi

BACKGROUND

Previous studies have characterized differences in vitiligo associated with halo nevi, but the features of vitiligo presenting with halo nevus in children have yet to be fully described.

AIMS

We sought to provide an epidemiologic and clinical comparison of cases of childhood vitiligo presenting with or without associated halo nevi.

MATERIALS AND METHODS

This was a retrospective chart review of children diagnosed with vitiligo in an academic pediatric dermatology practice from January 1990 to November 2014. The characteristics of children with vitiligo with or without associated halo nevi were compared.

RESULTS

Halo nevi were identified in 55 (26%) of 208 children with vitiligo. Patients with halo nevi were significantly more likely to be male and develop vitiligo at a later age. Children with vitiligo associated with halo nevi were more likely to present with generalized vitiligo, defined according to the presence of bilateral macules.

DISCUSSION

There was no significant association between groups in the percentage of body surface area with vitiligo or family history of vitiligo or autoimmune diseases. Patients with halo nevi were no more likely to develop new areas of vitiligo during the follow-up period, but there was a nonsignificant trend toward a higher rate of repigmentation in vitiligo associated with halo nevus.

CONCLUSION

Halo nevi are a common finding in children with vitiligo. The presence of a halo nevus in a child with vitiligo is associated with generalized vitiligo. The presence of a halo nevus does not significantly alter the risk of disease progression and rate of treatment.

A comparative study of mitochondrial ultrastructure in melanocytes from perilesional vitiligo skin and perilesional halo nevi skin

Vitiligo and halo nevi are both pigmentary disorders of the skin characterized by the acquired loss of functional epidermal melanocytes manifesting as white macules and patches. The cellular mechanism(s) and biochemical changes that result in the appearance of these two types of achromic lesions are still uncertain; and the relationship between vitiligo and halo nevi has been in dispute. In this study, we investigated the ultrastructure of mitochondria in melanocytes and in keratinocytes from perilesional vitiligo skin and from perilesional halo nevi skin using Transmission Electron Microscopy. Furthermore, we performed a quantitative analysis of mitochondrial morphology through a stereological study. As previously reported, we found that melanocytes from perilesional active vitiligo skin were loosely connected with their surroundings by their retracted dendrites. The surface density and the volume density of mitochondria in melanocytes and in keratinocytes from perilesional vitiligo skin are increased significantly compared with the controls, especially in active vitiligo. In contrast, there are no significant differences in mitochondria in melanocytes and in keratinocytes from perilesional halo nevi skin compared with the controls. In summary, the tendency of different morphologic alterations in mitochondria from perilesional vitiligo skin and from perilesional halo nevi skin reflect heterogeneous backgrounds between the two diseases, revealing that vitiligo and halo nevi may have separate pathogenic mechanisms. These findings may help elucidate the relationship of these two diseases and their underlying mechanisms.

Vitiligo as a systemic disease

Vitiligo is an acquired depigmentary skin disorder of unknown etiology. Vitiligo is not only a disease of melanocytes of the skin. Human melanocytes are derived from the neural crest and are located on various parts of the body. The involvement of skin melanocytes is the most visible one, but a systemic involvement of melanocytes can be observed. Some types of vitiligo (nonsegmental vitiligo) may also be associated with various diseases, mainly with autoimmune pathogenesis. Vitiligo represents a spectrum of many different disorders with different etiologies and pathogeneses, causing a common phenotype: the loss of melanocytes and/or their products. This phenotype is always consistent with a systemic involvement.

Association of giant congenital melanocytic nevus, halo nevus and vitiligo in a 75-year-old patient

A giant congenital melanocytic nevus represents a rare condition. The halo phenomenon may be seen in congenital or acquired melanocytic nevi. In the literature, association of halo nevus and giant congenital melanocytic nevus is rare and the association of both with vitiligo even more rare. A 75-yearold woman at first consultation complained of a hyperchromic bluish-brown hairy macula on the lower back, buttocks and thighs present since birth and an achromic halo of onset three years ago. The histological features were consistent with congenital melanocytic nevus and halo nevus, respectively. After two years the patient developed achromic areas in normal skin, histologically consistent with vitiligo. The authors emphasize the rarity of this triple combination, the patient's age and the absence of malignant degeneration to date.

Association of halo nevus/i and vitiligo in childhood: a retrospective observational study

BACKGROUND

Although halo nevus (HN) is frequently observed, the relationship between vitiligo and HN in children has rarely been investigated.

OBJECTIVES

To investigate the association between HN and vitiligo in children and understand if HN/HNi might be a risk factor for vitiligo.

METHODS

Ninety-eight patients with only HN/HNi and 27 with HN/HNi and vitiligo were investigated for number and localization of HN/HNi, family history for HN/HNi and vitiligo and personal and family history for autoimmune or other diseases. A follow-up telephone interview was performed to investigate the evolution of HN/HNi and the possible onset of vitiligo and/or other diseases.

RESULTS

In the HN/HNi and vitiligo group, HN/HNi and vitiligo had started almost simultaneously in 11 children; in nine, the onset of HN/HNi was followed by vitiligo after 6 months to 5 years; seven patients presented vitiligo first and HN/HNi after 3-9 years. Patients with associated vitiligo had, significantly more often, multiple HNi and a positive personal and/or family history of autoimmune thyroiditis compared with those with only HN/HNi. Follow-up longer than 5 years was available in 54/98 patients with only HN/HNi; two of them, both with multiple HNi, developed vitiligo. After follow-up, multiple HNi were noticed in 18/52 patients without vitiligo and in 9/11 of those in whom HN/HNi heralded vitiligo (s.s.).

CONCLUSIONS

In patients with multiple HNi, the risk of vitiligo and other autoimmune diseases seems to be higher than in pediatric patients with a single HN; clinicians should pay particular attention to children with multiple HNi and personal or family history of autoimmune diseases.

Targeting skin: vitiligo and autoimmunity

In this issue, Singh and co-workers describe the results of classical typing of human leukocyte antigen (HLA) alleles in 1,404 vitiligo patients and 902 unaffected controls from North India and follow-up HLA typing in 355 cases and 441 controls from Gujarat. The increased frequency of DRB1*07:01 in North Indian and Gujarat populations with generalized and localized vitiligo and in several vitiligo populations studied previously suggests that it contributes to autoimmunity and destruction of melanocytes.

HLA alleles and amino-acid signatures of the peptide-binding pockets of HLA molecules in vitiligo

Vitiligo is a depigmenting disorder of the skin that is characterized by the loss of functional melanocytes from the lesional sites. Although the exact etiology is not understood, autoimmunity is thought to be a crucial deterministic factor. A recurring theme of several autoimmune disorders is the aberrant presentation of self-antigens to the immune system, which triggers downstream perturbations. Here we examine the role of alleles of HLA class I and class II loci to delineate vitiligo manifestation in two distinct populations. Our studies have identified three specific alleles, HLA-A*33:01, HLA-B*44:03, and HLA-DRB1*07:01, to be significantly increased in vitiligo patients as compared with controls in both the initial study on North Indians (N=1,404) and the replication study in Gujarat (N=355) cases, establishing their positive association with vitiligo. Both generalized and localized vitiligo have the same predisposing major histocompatibility complex alleles, i.e., B*44:03 and DRB1*07:01, in both the populations studied, beside the differences in the frequencies of other alleles, suggesting that localized vitiligo too may be an autoimmune disorder. Significant differences in the amino-acid signatures of the peptide-binding pockets of HLA-A and HLA-B α-chain and HLA-DR β-chain were observed between vitiligo patients and unaffected controls.

A single nucleotide polymorphism rs9468925 of MHC region is associated with clinical features of generalized vitiligo in Chinese Han population

BACKGROUND

Vitiligo has been found to be associated with different HLA antigens in different ethnic groups. In our previous genome-wide association study (GWAS), we identified independent association signal of rs9468925 (P = 2.21 × 10(-33), OR = 0.74) within HLA-C-HLA-B region.

OBJECTIVES

To explore the association between rs9468925 polymorphism within MHC and the clinical features of generalized vitiligo.

METHODS

The study, using 5566 cases and 6462 controls from previous GWA study investigated the single and combined (GA + GG) genotypic distribution of rs9468925 in subsets of vitiligo patients having different clinical features. We performed a QTL analysis (quantitative trait locus) for age of onset with genotype of rs9468925.

RESULTS

The GA + GG genotypic distribution of SNP rs9468925 tested with an additive model was found to be significantly different in subgroups of patients of >20 vs. <20 years old (genotypic P = 2.57 × 10(-4), combined P = 3.0 × 10(-3), OR = 0.77, 95% CI: 0.64-0.92), and in patients with different clinical subtypes of vitiligo (genotypic P = 0.03, combined P = 5.0 × 10(-3)). However, there was no statistical significance for familial history, halo nevi involvement and autoimmune disease involvement.

CONCLUSIONS

Allele G of rs9468925 on HLA-C-HLA-B may be associated with a higher risk of vitiligo. Our study showed a significant genotypic variation between patients with age of onset ≤ 20 years and age of onset >20 years. Obvious clinical differences of generalized vitiligo related to genotypic variation found in the Chinese Han population were confirmed in this study.

Prognostic value and clinical significance of halo naevi regarding vitiligo

BACKGROUND

Vitiligo and halo naevi can present together or separately. Whether they are different entities remains unclear.

OBJECTIVES

To assess the clinical significance of halo naevi, both with respect to the future development of vitiligo, and to the clinical profile and course of vitiligo.

METHODS

In total, 291 patients were included in this study: patients with only halo naevi (group 1; n=40), patients with generalized vitiligo without halo naevi (group 2; n=173) and patients with generalized vitiligo with halo naevi (group 3; n=78).

RESULTS

Patients with only halo naevi (group 1) reported significantly less associated autoimmune disease (P=0·001), were less likely to have a family history of vitiligo (P=0·013) and were less likely to have presence of Koebner phenomenon (P<0·001) compared with patients with generalized vitiligo (groups 2+3). Multiple halo naevi (≥3) were significantly more frequently observed (P=0·002) in patients from group 1 compared with patients from group 3. In group 3, halo naevi were reported prior to the development of vitiligo in 61% (mean±SD time interval of 33·7±5·17months). No significant correlation was observed between the presence of halo naevi and the extent, activity or subtype of vitiligo. However, halo naevi in patients with vitiligo significantly reduced the risk for associated autoimmune diseases, and age at onset of vitiligo was significantly lower compared with patients with vitiligo without halo naevi (P<0·001).

CONCLUSIONS

Our results support the hypothesis that halo naevi can represent a distinct condition. In a subset of patients, the occurrence of halo naevi may be an initiating factor in the pathogenesis of vitiligo.

Vitiligo in an Italian outpatient center: a clinical and serologic study of 204 patients in Tuscany

BACKGROUND

Vitiligo is a depigmentation disorder resulting from destruction of cutaneous melanocytes that affects 0.1-2% of the world's population, irrespective of sex and race.

OBJECTIVE

To investigate the clinical and immunopathologic characteristics of a series of Italian vitiligo patients.

METHODS

We examined clinical and immunopathologic data of 204 patients affected by vitiligo at a university-based dermatology outpatient hospital (second clinic) between January 1998 and March 2008. In particular, the clinical-epidemiologic characteristics of our patients, serologic parameters suggestive of immune/autoimmune activity (autoantibodies, immune complexes, complement, immunoglobulins), and the association between vitiligo and HLAs were investigated.

RESULTS

Upon comparison of our results with control and literature values, the following aspects appeared to be in complete agreement: the frequency of clinical subtypes of vitiligo, an earlier onset of segmental compared with non-segmental vitiligo, the association of familial vitiligo with other autoimmune diseases, the greater association of non-segmental vitiligo than segmental vitiligo with autoimmune diseases, and some features of pediatric vitiligo. Other data were partially consistent with the literature, such as the association between vitiligo and autoimmune diseases/autoantibody activities, and the association between vitiligo and HLAs. Finally, a portion of our data did not concur with the literature, including the sex distribution and mean age of onset, the lack of association between halo nevi and autoimmune diseases, and some aspects of pediatric vitiligo.

CONCLUSIONS

This study provides novel information regarding clinical features and serologic parameters in different subgroups of vitiligo, namely a significant association between active vitiligo and autoantibody activities, and significant clinical differences (i.e. activity of disease, age of onset, and coexistence of other autoimmune diseases) between vitiligo associated with autoantibodies and vitiligo negative for autoantibodies.

Vitiligo, reactive oxygen species and T-cells

The acquired depigmenting disorder of vitiligo affects an estimated 1% of the world population and constitutes one of the commonest dermatoses. Although essentially asymptomatic, the psychosocial impact of vitiligo can be severe. The cause of vitiligo remains enigmatic, hampering efforts at successful therapy. The underlying pathogenesis of the pigment loss has, however, been clarified to some extent in recent years, offering the prospect of effective treatment, accurate prognosis and rational preventative strategies. Vitiligo occurs when functioning melanocytes disappear from the epidermis. A single dominant pathway is unlikely to account for all cases of melanocyte loss in vitiligo; rather, it is the result of complex interactions of biochemical, environmental and immunological events, in a permissive genetic milieu. ROS (reactive oxygen species) and H2O2 in excess can damage biological processes, and this situation has been documented in active vitiligo skin. Tyrosinase activity is impaired by excess H2O2 through oxidation of methionine residues in this key melanogenic enzyme. Mechanisms for repairing this oxidant damage are also damaged by H2O2, compounding the effect. Numerous proteins and peptides, in addition to tyrosinase, are similarly affected. It is possible that oxidant stress is the principal cause of vitiligo. However, there is also ample evidence of immunological phenomena in vitiligo, particularly in established chronic and progressive disease. Both innate and adaptive arms of the immune system are involved, with a dominant role for T-cells. Sensitized CD8+ T-cells are targeted to melanocyte differentiation antigens and destroy melanocytes either as the primary event in vitiligo or as a secondary promotive consequence. There is speculation on the interplay, if any, between ROS and the immune system in the pathogenesis of vitiligo. The present review focuses on the scientific evidence linking alterations in ROS and/or T-cells to vitiligo.

Possible transfer of vitiligo by allogeneic bone marrow transplantation: a case report

Among the cases yet published of development of vitiligo after BMT, only two can claim as possible adoptive transfer of such disease. We report a case of a patient with sickle cell disease in whom vitiligo developed after allogeneic BMT from his HLA identical father affected by vitiligo. We reviewed and searched for some particularities in the reported cases of post-BMT vitiligo.

Halo congenital nevocellular nevi associated with extralesional vitiligo: a case series with review of the literature

Halo formation in association with congenital nevi is uncommon and is postulated to have an immunologic etiology. In this report, we present nine cases of patients with congenital nevi and vitiligo who uniquely developed both halo formation around the nevi in addition to vitiligo formation in distinctly separate locations. While the precise etiology of halo formation and vitiligo remains uncertain, several theories suggest that both phenomena result from an immunologic response to pigment cells, whether in the "normal" skin of vitiligo or in the excessively pigmented congenital nevus.

Development of Halo Nevus Around Nevus Spilus as a Central Nevus, and the Concurrent Vitiligo

Halo nevus is a benign melanocytic nevus that is surrounded by a hypopigmented zone. The most frequent association with halo nevus is vitiligo, and this also appears in nearby regions, as well as at other remote sites. Although the mechanism for developing the depigmentation around nevus spilus is uncertain an immunologic process may be responsible for the finding of inflammatory infiltrates of the upper dermis in the depigmented lesions. We report here on a 13-year-old boy who showed a depigmented zone around a nevus spilus on the right side of his neck with simultaneous vitiligo lesions on the face.

Origin, clinical presentation, and diagnosis of hypomelanotic skin disorders

Hypomelanotic skin disorders are cutaneous pigmentary disorders characterized by a reduced melanin content in the skin that results in a lightening of the skin. Establishing the correct diagnosis for hypomelanotic skin disorders requires a good history, a detailed physical examination, the use of special lighting techniques, such as Wood's light, and sometimes a biopsy of the abnormally pigmented skin and the normally pigmented skin. This article focuses on the origin, clinical presentation, and diagnosis of acquired hypomelanotic skin disorders. An algorithm for the diagnostic approach to these hypomelanoses is given.

Vitiligo puzzle: the pieces fall in place

Over the years, the role of biochemical, immunological, genetic, and other biological aspects in the pathogenesis of vitiligo has been studied. So far, no convincing model describing the interplay of these contributing factors has been formulated. Based on existing research, we propose that vitiligo has a multi-factorial etiology, characterized by multiple steps, but always involving an increase of external or internal phenol/catechol concentration, serving as a preferred surrogate substrate of tyrosinase, competing with its physiological substrate tyrosine. The conversion of these substrates into reactive quinones is reinforced by a disturbed redox balance (increasing hydrogen peroxide). Such reactive quinones can be covalently bound to the catalytic centre of tyrosinase (haptenation). This could give rise to a new antigen, carried by Langerhans cells to the regional lymph node, stimulating the proliferation of cytotoxic T cells. However, the activation of such cytotoxic cells is only a first step in skin melanocyte killing, which also depends on a shift in the balance between immune defence and tolerance, e.g. resulting from a decrease in properly functioning T-regulatory cells. With this new model, based on a synthesis of several of the existing theories, in mind, the external and internal factors involved in the etiopathogenesis of vitiligo are reviewed, against the background of reported clinical data, experimental studies and existing and potential new therapies. A similar complex mechanism may also lead to some other autoimmune diseases.

Evidence for two susceptibility loci on chromosomes 22q12 and 6p21-p22 in Chinese generalized vitiligo families

Vitiligo is an acquired depigmentation disorder of the skin and hair caused by the selective destruction of melanocytes from the epidermis that gives rise to well-defined depigmented patches. Strong genetic predisposition has been well recognized. Previous reports have described five significant vitiligo susceptibility loci spread over five different chromosomes, 1p31 (AIS1), 7q (AIS2), 8p (AIS3), 4q13-q21 (AIS4), and 17p (SLEV1). In addition, our previous genome-wide scan of 106 Chinese vitiligo families presented suggestive linkages on five additional chromosome segments, 1p36, 6p21-p22, 6q24-q25, 14q12-q13, and 22q12. To clarify the significance of these suggestive loci, we have now extended this study to a total of 143 Chinese vitiligo families and increased the marker density. Two linkage signals on 6p21-p22 and 22q12 that were previously only suggestive now meet genome-wide criteria for significant linkage, establishing their importance as major vitiligo susceptibility loci. Linkage signals on 1p36 and 6q24-q25 did not improve our previous findings, but on 14q showed negative in the 143 family cohorts. The results presented here further demonstrate the genetic complexity of vitiligo pathogenesis and point to new chromosomal locations for further research to identify the specific genes involved in this process.

The definition and assessment of vitiligo: a consensus report of the Vitiligo European Task Force

Vitiligo is the most common depigmenting disorder, which affects 0.5-1% of the worldwide population, causing disfigurement and serious disturbances in well being. There is a current lack of consensus in definition and methods of assessment of this disorder, which makes it generally impossible to compare the outcomes of different studies of the same treatment. This report summarizes the work carried out by the Vitiligo European Task Force to propose a consensus definition of the disease and to assess treatment outcomes using a system which combines analysis of extent, stage of disease (staging), and disease progression (spreading). In summary, extent is evaluated using the rule of 9. Staging is based on cutaneous and hair pigmentation in vitiligo patches, and the disease is staged 0-3 (revised version) on the largest macule in each body region, except hands and feet, which are assessed separately and globally as one unique area. Assessment of spreading is based on Wood's lamp examination of the same largest macule in each body area. Wood's lamp is useful for a combined assessment of staging and spreading in the same selected area. This study reports a workshop which validated the clinical use of the assessment form performed at several European University clinics, and showed an overall good concordance among panelists using the proposed scoring system. This system can be easily handled in clinical practice. However, variations between scorer profiles indicate a need for training to decrease interobserver variability. Further steps are envisaged, namely: (i) build a global index including staging and spreading for the initial assessment of vitiligo patients, usable as a guidance for therapeutic indications and prognosis, which could be interpreted as an equivalent of the TNM (tumor, node, metastasis) system for cancer; (ii) implement large-scale tests necessary for clinical trials (to check reproducibility and sensitivity); (iii) carry out studies of automated devices to assess extent more accurately; (iv) set up a teaching tool for scoring vitiligo, which could be posted on a website; and (v) set up an international conference on classifying, staging and scoring vitiligo, through the IFPCS Special Interest Group on Vitiligo.

The genetic concept of vitiligo

Vitiligo is a relatively common, acquired pigmentary disorder characterized by areas of depigmented skin resulting from loss of epidermal melanocytes. The prevalence of this disease varies from 0.1 to 2% in various global populations. The genetics of vitiligo cannot be explained by simple Mendelian genetics; it is characterized by incomplete penetrance, multiple susceptibility loci and genetic heterogeneity. Unraveling the complex genetics of vitiligo is a daunting challenge but the perseverance of vitiligo gene hunters has produced commendable results in recent years. Although environmental factors are important, there is considerable evidence that genes also play a significant role in its pathogenesis. Strong evidence from twin and family studies indicates the importance of genetic factors in the development of vitiligo, although it is clear that these influences are complex. Linkage and association studies have also provided strong support for vitiligo susceptibility genes on chromosomes 4q13-q21, 1p31, 7q22, 8p12 and 17p13, while loci of interest at 6p, 6q, 14q, 9q, 13q, 19p and 22q require further follow-up. Although important obstacles to further progress will need to be overcome, the successes of the past 5 years suggest that a detailed description of the genetic basis of vitiligo is a realistic goal. In the future, dissection of the complex genetic architecture of vitiligo will provide new approaches for treatment and prevention. In this article, we will give an overview of the latest findings in the genetics of vitiligo.

A novel linkage to generalized vitiligo on 4q13-q21 identified in a genomewide linkage analysis of Chinese families

Generalized vitiligo is a common, autoimmune, familial-clustering depigmentary disorder of the skin and hair that results from selective destruction of melanocytes. Generalized vitiligo is likely a heterogeneous disease, with five susceptibility loci reported so far--on chromosomes 1p31, 6p21, 7q, 8p, and 17p13--in white populations. To investigate vitiligo susceptibility loci in the Chinese population, we performed a genomewide linkage analysis in 57 multiplex Chinese families, each with at least two affected siblings, and we identified interesting linkage evidence on 1p36, 4q13-q21, 6p21-p22, 6q24-q25, 14q12-q13, and 22q12. Subsequently, to extract more linkage information, we investigated our initial genomewide linkage findings in a follow-up analysis of 49 new families and additional markers. Our initial genomewide linkage analysis and our subsequent follow-up analysis have identified a novel linkage to vitiligo on 4q13-q21, with highly significant linkage evidence (a nonparametic LOD score of 4.62 [P=.000003] and a heterogeneity LOD score of 4.01, under a recessive inheritance model), suggesting that 4q13-q21 likely harbors a major susceptibility locus for vitiligo in the Chinese population. We observed a minimal overlap between the linkage results of our current genomewide analysis in the Chinese population and the results of previous analyses in white populations, and we thus hypothesize that, as a polygenic disorder, vitiligo may be associated with great genetic heterogeneity and a substantial difference in its genetic basis between ethnic populations.

Physiopathology and genetics of vitiligo

Generalized vitiligo is an acquired disorder in which white patches of skin and overlying hair result from autoimmune loss of melanocytes from involved areas. The autoimmune pathogenesis of vitiligo has become a rapidly evolving field of research. A humoral immune reaction has been implicated through the detection of circulating antibodies. However, recent research focuses on a melanocyte-specific cytotoxic-T-cell immune reaction in the melanocyte destruction. Several candidate genes have been proposed for vitiligo susceptibility. They include genes important for melanin biosynthesis, response to oxidative stress and/or regulation of autoimmunity. A recent genome-wide scan performed on families with numerous members presenting vitiligo has clearly revealed linkage of susceptibility loci.