Rasmussen encephalitis associated with segmental vitiligo of the scalp: clinicopathologic report

Poliosis, hair pigment dilution, and premature graying of the hair: A diagnostic approach in pediatric patients and review of the literature

Poliosis is defined as the absence of melanin in hair, and hair graying typically occurs with hair melanin reduction. Poliosis can occur at any age but presents in childhood in certain genetic and acquired conditions, with many families seeking evaluation from a pediatric dermatologist. Poliosis presents as white hair typically restricted to a certain location of the scalp. Children may also present with a reduction of expected hair pigmentation, referred to as pigment dilution, or the development of hair graying. This review aims to provide a streamlined diagnostic approach for pediatric dermatologists when presented with these hair findings. Poliosis should be recognized as a potential diagnostic feature or initial sign in many syndromes and thus can guide clinicians in diagnosing and managing conditions earlier in a patient's care. Since many of the genetic and acquired conditions that present with poliosis or hair pigment dilution have extracutaneous manifestations, early diagnosis is vital in establishing multidisciplinary care.

Autoimmunity in Segmental Vitiligo

The autoimmune basis of segmental vitiligo (SV) has only recently been recognized. Systemic autoimmune diseases are less frequently associated compared to non-segmental vitiligo (NSV), but localized skin disorders - in particular linear morphea - have been repeatedly observed in patients with SV. The inflammatory response is documented on a clinical level with cases displaying erythematous borders or a hypochromic stage, on a histopathological level with predominantly CD8 lymphocytes migrating toward the basal layer and by flow cytometry demonstrating the antimelanocyte specificity of these cytotoxic T cells. The increased risk for halo naevi and NSV in these patients further underline the immune-mediated mechanisms of SV. Nonetheless, the localized and unique distribution pattern points to somatic mosaicism. This places SV in a category of similar diseases such as lichen striatus, blaschkitis, linear lupus erythematosus, and linear scleroderma where an immune reaction against genetically mutated skin cells is believed to be the underlying cause. All these disorders are characterized by a young age of onset, a temporary disease activity with spontaneous resolution, limited response to treatment, and often long-term sequelae. Although challenging, genetic research proving this genetic mosaicism could offer crucial insights into the pathogenesis of both segmental and non-segmental vitiligo.

Investigation of the Role of Interleukin 6 in Vitiligo Pathogenesis

Interleukin-6 (IL6) is involved in pathogenesis of several autoimmune disorders including vitiligo. Hence, we aimed to investigate the association of IL6 -174 G/C and -572 G/C polymorphisms and its transcript levels with vitiligo; to evaluate the effect of IL-6 on normal human melanocyte (NHM) viability and expression of IL6R, MITF and TYR. IL6 -174 G/C and -572 G/C polymorphisms were genotyped by ARMS-PCR and PCR-RFLP respectively in 343 controls and 322 vitiligo patients. IL6 transcript levels were estimated from PBMCs (96 controls and 77 patients) and skin samples (15 controls and 15 patients) by qPCR. NHM viability was assessed by MTT; IL6R, MITF and TYR transcript and protein levels were monitored by qPCR and ICC respectively. Genetic analyses revealed no association of IL6 -174 G/C polymorphism (p> .05) with vitiligo. Analysis of IL6 -572 G/C revealed reduced risk of vitiligo in individuals with GC/CC genotypes compared to GG genotype (p = .010). IL6 expression was significantly increased (p = .0197) in PBMCs of patients. Further, IL6 expression was significantly higher in non-lesional skin compared to controls (p = .009). In-vitro NHM viability was decreased upon IL-6 exposure (10-50 ng/ml; p< .05), with significantly increased IL6R transcript (p = .042) and protein levels (p = .003) however, MITF transcript (p = .0003) and protein levels (p = .016), and TYR transcript levels (p = .001) were significantly decreased. The results suggest that IL6 -572 G/C polymorphism might be associated with vitiligo susceptibility in Gujarat population. Moreover, increased IL6 expression in vitiligo patients and its effect on NHM suggest a potential role in melanocyte biology.

CONCLUSION

The results suggest that IL6 - 572 G/C polymorphism might be associated with vitiligo susceptibility in Gujarat population. Moreover, increased IL6 expression in vitiligo patients and its effect on NHM suggest a potential role in melanocyte biology.

Evidence for Resident Memory T Cells in Rasmussen Encephalitis

Rasmussen encephalitis (RE) is a rare pediatric neuroinflammatory disease of unknown etiology characterized by intractable seizures, and progressive atrophy usually confined to one cerebral hemisphere. Surgical removal or disconnection of the affected cerebral hemisphere is currently the only intervention that effectively stops the seizures. Histopathological evaluation of resected brain tissue has shown that activated brain resident macrophages (microglia) and infiltrating T cells are involved in the inflammatory reaction. Here, we report that T cells isolated from seven RE brain surgery specimens express the resident memory T cell (T_RM) marker CD103. CD103 was expressed by >50% of CD8⁺ αβ T cells and γδ T cells irrespective of the length of time from seizure onset to surgery, which ranged from 0.3 to 8.4 years. Only ~10% of CD4⁺ αβ were CD103⁺, which was consistent with the observation that few CD4⁺ T cells are found in RE brain parenchyma. Clusters of T cells in brain parenchyma, which are a characteristic of RE histopathology, stained for CD103. Less than 10% of T cells isolated from brain specimens from eight surgical cases of focal cortical dysplasia (FCD), a condition that is also characterized by intractable seizures, were CD103⁺. In contrast to the RE cases, the percent of CD103⁺ T cells increased with the length of time from seizure onset to surgery. In sections of brain tissue from the FCD cases, T cells were predominantly found around blood vessels, and did not stain for CD103. The presence of significant numbers of T_RM cells in RE brain irrespective of the length of time between clinical presentation and surgical intervention supports the conclusion that a cellular immune response to an as yet unidentified antigen(s) occurs at an early stage of the disease. Reactivated T_RM cells may contribute to disease progression.

Potential role of neurogenic inflammatory factors in the pathogenesis of vitiligo

BACKGROUND

Vitiligo is a highly complex multifactorial condition of the skin that has an unclear mechanism of pathogenesis.

OBJECTIVE

This review summarizes the role of various neurogenic inflammatory factors significantly upregulated in vitiligo.

METHODS

A literature review was conducted of all pertinent data regarding neuropeptides that are altered in vitiligo and their possible role in the destruction of melanocytes.

RESULTS

The close associations between the skin, immune system, and nervous system, along with specific changes demonstrated in vitiligo patients, support a pathogenic mechanism of vitiligo that involves neuroimmunologic factors, the release of which can be governed by mental stress.

CONCLUSION

Neuropeptides and nerve growth factors are critical regulators of emotional response and may precipitate the onset and development of vitiligo in certain predisposed individuals. More studies are required to investigate whether a direct link exists between genetics, mental stress, and neurogenic factors in vitiligo.