Systemic epidermal nevus with involvement of the oral mucosa due to FGFR3 mutation

Genotype-phenotype spectrum and correlations in Chinese patients with keratinocytic epidermal naevus: A retrospective study of 22 cases

Background Keratinocytic epidermal naevus is characterised by hyperkeratotic lesions arranged along Blaschko's lines. So far, multiple genes have been implicated, but there is no detailed data or genotype-phenotype correlation studies of keratinocytic epidermal naevi in Chinese patients. Objective To evaluate the clinical, histopathological and genetic features, genotype-phenotype correlations of keratinocytic epidermal naevus in the Chinese population. Methods A retrospective study of patients with keratinocytic epidermal naevi referred to the Department of Dermatology, West China Hospital, in the last four years. Medical history, clinical data, histopathological characteristics, and evidence of genetic mutations were collected from 22 unrelated Chinese patients with this problem. Results The distribution of the keratinocytic epidermal naevi exhibited right-side dominance. Non-epidermolytic epidermis naevus was much more common. Eight reported missense mutations were found in this study, which were detected in five genes, including HRAS, KRT10, FGFR3, GJB2, and PIK3CA. HRAS was the most commonly affected gene (9/22, 40.91%) in this study, with the c.37G>C (6/22, 27.27%) substitution representing a possible hotspot mutation. Mutation allele loads were higher in the affected lesions than blood samples. Epidermolytic epidermal naevus was found in three patients exclusively carrying KRT10 mutations. Inflammatory epidermal naevi were caused by mutations of KRT10 and PIK3CA. Most of the mosaic mutations detected in keratinocytic epidermal naevi patients were the same as germline mutations identified in systemic diseases caused by these genes. Limitations The retrospective nature of the study. Conclusion Our findings reveal the genotype-phenotype spectrum and their correlation amongst Chinese patients with keratinocytic epidermal naevi. In addition, our data underscores the importance of genetic testing in lesional skin to help characterise and categorise keratinocytic epidermal naevi, decide on a therapeutic strategy, and offer genetic counselling and prenatal diagnosis.

Case Report: Sequential postzygotic HRAS mutation and gains of the paternal chromosome 11 carrying the mutated allele in a patient with epidermal nevus and rhabdomyosarcoma: evidence of a multiple-hit mechanism involving HRAS in oncogenic transformation

We report a 7-year-old boy born with epidermal nevi (EN) arranged according to Blaschko's lines involving the face and head, right upper limb, chest, and left lower limb, who developed a left paratesticular embryonal rhabdomyosarcoma at 18 months of age. Parallel sequencing identified a gain-of-function variant (c.37G>C, p.Gly13Arg) of HRAS in both epidermal nevus and tumor but not in leukocytes or buccal mucosal epithelial cells, indicating its postzygotic origin. The variant accounted for 33% and 92% of the total reads in the nevus and tumor DNA specimens, respectively, supporting additional somatic hits in the latter. DNA methylation (DNAm) profiling of the tumor documented a signature consistent with embryonal rhabdomyosarcoma and CNV array analysis inferred from the DNAm arrays and subsequent MLPA analysis demonstrated copy number gains of the entire paternal chromosome 11 carrying the mutated HRAS allele, likely as the result of paternal unidisomy followed by subsequent gain(s) of the paternal chromosome in the tumor. Other structural rearrangements were observed in the tumours, while no additional pathogenic variants affecting genes with role in the RAS-MAPK and PI3K-AKT-MTOR pathways were identified. Our findings provide further evidence of the contribution of "gene dosage" to the multistep process driving cell transformation associated with hyperactive HRAS function.

Transcriptomic Analysis of Human Keratinocytes Treated with Galactomyces Ferment Filtrate, a Beneficial Cosmetic Ingredient

Galactomyces ferment filtrate (GFF, Pitera™) is a cosmetic ingredient known to have multiple skin care benefits, such as reducing redness and pore size via the topical application of its moisturizer form. Although GFF is known to act partly as an antioxidative agonist for the aryl hydrocarbon receptor (AHR), its significance in keratinocyte biology is not fully understood. In this study, we conducted a transcriptomic analysis of GFF-treated human keratinocytes. Three different lots of GFF consistently modulated 99 (22 upregulated and 77 downregulated) genes, including upregulating cytochrome P450 1A1 (CYP1A1), a specific downstream gene for AHR activation. GFF also enhanced the expression of epidermal differentiation/barrier-related genes, such as small proline-rich proteins 1A and 1B (SPRR1A and SPRR1B), as well as wound healing-related genes such as serpin B2 (SERPINB2). Genes encoding components of tight junctions claudin-1 (CLDN1) and claudin-4 (CLDN4) were also target genes upregulated in the GFF-treated keratinocytes. In contrast, the three lots of GFF consistently downregulated the expression of inflammation-related genes such as chemokine (C-X-C motif) ligand 14 (CXCL14) and interleukin-6 receptor (IL6R). These results highlight the beneficial properties of GFF in maintaining keratinocyte homeostasis.

Epidermal Nevus Syndrome Associated with Dwarfism and Atopic Dermatitis

Epidermal nevus syndrome (ENS) is a congenital disorder characterized by widespread linear epidermal lesions consisting of epidermal nevus and extracutaneous involvements, especially of the central nervous system and skeletal system. Garcia-Hafner-Happle syndrome, also known as fibroblast growth factor receptor 3 (FGFR3)-ENS, is characterized by a systematized keratinocytic EN of soft and velvety type with neurological abnormalities such as seizures, intellectual impairment, and cortical atrophy. We present a case of a 9-year-old Japanese boy afflicted with Garcia-Hafner-Happle syndrome associated with dwarfism and atopic dermatitis. We show the results of physical examination, DNA analysis, and imaging studies and discuss the mutation underlying the child's disorder.

Nevus Unius Lateris with Bilateral Oral Mucosal Lesions: An Unusual Presentation

Verrucous epidermal nevi (VEN) are cutaneous hamartomas characterized by keratinocytic hyperplasia. Majority are linear in distribution and tend to follow the Blaschko lines; however, some may have zosteriform (segmental) or systematized distribution involving widespread areas of skin. The systematized ones are further classified into “Nevus Unius Lateris” when one-half of the body is affected, and “Ichthyosis Hystrix” showing bilateral distribution, both being the uncommon forms. Although it can affect any body part, it rarely involves the head and neck region with seldom involvement of mucosae, scalp, and ear lobes. We saw a 6-year-old child with multiple hyperpigmented verrucous plaques predominantly present over left half of the body, ipsilateral alopecia scalp, and verrucous lesions involving mucosae of palate and tongue, which were present bilaterally. Previously, case reports of oral lesions related to VEN had demonstrated segmental, midline, or unilateral distribution. Hereby, we report this peculiar case of Nevus Unius Lateris with bilateral oral mucosal involvement, owing to its rarity.

Mosaic abnormalities of the skin: review and guidelines from the European Reference Network for rare skin diseases

BACKGROUND

Cutaneous mosaicism is an area of dermatology in which there has been an explosion of knowledge within the current decade. This has led to fundamental changes in the understanding of the conditions in this field, and to an ongoing paradigm shift in the approach to management of mosaic skin disorders.

OBJECTIVES

To lay out the general principles of mosaicism as they are currently understood, summarize the known cutaneous mosaic abnormalities of the skin with associated phenotypic and genotypic information, review the latest trials on targeted therapies and propose guidelines for the general approach to a patient with suspected mosaicism.

METHODS

This was a consensus expert review as part of the European Reference Network project (ERN-Skin).

CONCLUSIONS

This study provides clinicians with a practical approach to the patient with suspected mosaicism, redefines mosaicism for the modern genetic era, and proposes a new classification system based on genetic mechanism. What's already known about this topic? Cutaneous mosaicism is a complex field of dermatology that encompasses most birthmarks, and many rare syndromes. Some cutaneous patterns are known to be seen in mosaicism. Very few treatment options are available for most mosaic abnormalities of the skin. Recent high-sensitivity genetic techniques have led to an explosion of knowledge about genotype and phenotype in the literature. What does this study add? Expert consensus from the European Reference Network project. Review of knowledge of confirmed mosaic abnormalities of the skin, including cutaneous phenotype, extracutaneous associated features and genotype. Proposed new classification of mosaic abnormalities of the skin by genetic mechanism and therefore inheritance potential. Practical tips on correct sample collection and genetic investigation. Review of trials of targeted therapies. Guidelines for a practical clinical approach to the patient with suspected mosaicism.

Pigmentary mosaicism: a review of original literature and recommendations for future handling

Background

Pigmentary mosaicism is a term that describes varied patterns of pigmentation in the skin caused by genetic heterogeneity of the skin cells. In a substantial number of cases, pigmentary mosaicism is observed alongside extracutaneous abnormalities typically involving the central nervous system and the musculoskeletal system. We have compiled information on previous cases of pigmentary mosaicism aiming to optimize the handling of patients with this condition. Our study is based on a database search in PubMed containing papers written in English, published between January 1985 and April 2017. The search yielded 174 relevant and original articles, detailing a total number of 651 patients.

Results

Forty-three percent of the patients exhibited hyperpigmentation, 50% exhibited hypopigmentation, and 7% exhibited a combination of hyperpigmentation and hypopigmentation. Fifty-six percent exhibited extracutaneous manifestations. The presence of extracutaneous manifestations in each subgroup varied: 32% in patients with hyperpigmentation, 73% in patients with hypopigmentation, and 83% in patients with combined hyperpigmentation and hypopigmentation. Cytogenetic analyses were performed in 40% of the patients: peripheral blood lymphocytes were analysed in 48%, skin fibroblasts in 5%, and both analyses were performed in 40%. In the remaining 7% the analysed cell type was not specified. Forty-two percent of the tested patients exhibited an abnormal karyotype; 84% of those presented a mosaic state and 16% presented a non-mosaic structural or numerical abnormality. In patients with extracutaneous manifestations, 43% of the cytogenetically tested patients exhibited an abnormal karyotype. In patients without extracutaneous manifestations, 32% of the cytogenetically tested patients exhibited an abnormal karyotype.

Conclusion

We recommend a uniform parlance when describing the clinical picture of pigmentary mosaicism. Based on the results found in this review, we recommend that patients with pigmentary mosaicism undergo physical examination, highlighting with Wood’s light, and karyotyping from peripheral blood lymphocytes and skin fibroblasts. It is important that both patients with and without extracutaneous manifestations are tested cytogenetically, as the frequency of abnormal karyotype in the two groups seems comparable. According to the results only a minor part of patients, especially those without extracutaneous manifestations, are tested today reflecting a need for change in clinical practice.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0778-6) contains supplementary material, which is available to authorized users.

Epidermal nevus syndromes: New insights into whorls and swirls

Knowledge of the molecular underpinnings of many epidermal nevi and epidermal nevus syndrome has expanded rapidly in recent years. In this review and update on epidermal nevus syndrome, we will cover recent genetic discoveries involving epidermal nevi, including nevus sebaceus, keratinocytic epidermal nevus, nevus comedonicus, congenital hemidysplasia with ichthyosiform nevus and limb defects syndrome, phakomatosis pigmentokeratotica, Becker's nevus, porokeratotic adnexal ostial nevus, inflammatory linear verrucous epidermal nevi, and cutaneous-skeletal hypophosphatemia syndrome. We will discuss how newly defined mutations relate to the biology reflected in the cutaneous patterns seen in these mosaic disorders and how new molecular data has informed our understanding of these diseases and shaped management decisions.

Keratinocytic epidermal nevus syndrome with Schwann cell proliferation, lipomatous tumour and mosaic KRAS mutation

Background

Keratinocytic epidermal nevus syndrome (KENS) is a complex disorder not only characterized by the presence of epidermal nevi but also by abnormalities in the internal organ systems. A small number of cases with KENS are molecularly characterized and reported in the literature with somatic activating RAS, FGFR3 and PIK3CA mutations.

Case presentation

In this study we present a patient with hyper- and hypopigmented regions, verrucous pigmented skin lesions and a paravertebral conglomerate tumour at the level of the cervical and thoracic spine. A large lipomatous dumbbell tumour caused atrophy of the spinal cord with progressive paraparesis. We identified a mosaic c.35G > A (p.Gly12Asp) KRAS mutation in the pigmented verrucous epidermal nevus tissue, the intraneural schwann cells and the lipoma. The c.35G > A (p.Gly12Asp) KRAS mutation was absent in the peripheral blood leukocytes.

Conclusion

We conclude that KENS, the intraneural Schwann cell proliferation and the lipoma in this individual were caused by a postzygotic and mosaic activating c.35G > A (p.Gly12Asp) KRAS mutation.

Epidermal nevus syndromes

The term epidermal nevus syndrome (ENS) has been used to describe the association of epidermal hamartomas and extracutaneous abnormalities. Although many continue to use the term "ENS," it is now understood that this is not one disease, but rather a heterogeneous group with distinct genetic profiles defined by a common cutaneous phenotype: the presence of epidermal and adnexal hamartomas that are associated with other organ system involvement. One commonality is that epidermal nevi often follow the lines of Blaschko and it appears the more widespread the cutaneous manifestations, the greater the risk for extracutaneous manifestations. The majority of the extracutaneous manifestations involve the brain, eye, and skeletal systems. The CNS involvement is wide ranging and involves both clinical manifestations such as intellectual disability and seizures, as well as structural anomalies. Several subsets of ENS with characteristic features have been delineated including the nevus sebaceus syndrome, Proteus syndrome, CHILD syndrome, Becker's nevus syndrome, nevus comedonicus syndrome, and phakomatosis pigmentokeratotica. Advances in molecular biology have revealed that the manifestations of ENS are due to genomic mosaicism. It is likely that the varied clinical manifestations of ENS are due in great part to the functional effects of specific genetic defects. Optimal management of the patient with ENS involves an interdisciplinary approach given the potential for multisystem involvement. Of note, epidermal nevi have been associated with both benign and malignant neoplasms, and thus ongoing clinical follow-up is required.

Analysis of mutations in the PIK3CA and FGFR3 genes in verrucous epidermal nevus

Verrucous epidermal nevi are congenital hamartomas composed of keratinocytes and may occur alone or in association with developmental abnormalities. A close relationship between variations in the PIK3CA and FGFR3 genes and the appearance of nevi has been recently reported. Based on that, we performed molecular assays for the identification of E542K, E545G/K and H1047R mutations in the PIK3CA gene and of the R248C mutation in the FGFR3 gene. Interestingly, during the amplification process, we did not observe the PCR product of exon 9 of the PIK3CA gene, a region comprising amino acids 542-545. This strongly suggests the occurrence of a microdeletion of that region and indicates a possible allelic variant, which has not yet being described in the literature.

Late onset epidermal nevus with hypertrichosis and facial hemihypertrophy

Epidermal nevus syndromes are rare conditions, characterized by different types of keratinocytic or organoid epidermal nevi in association with ocular, neurological, and skeletal manifestations. We present a case of late onset epidermal nevus with hypertrichosis and hemihypertrophy of face. Genetic analysis did not reveal presence of FGFR3 or PIK3CA mutations. The patient has features that cannot be categorized into the present well-known syndromes.

Epidermal nevus and ameloblastoma: a rare association

Epidermal nevi are clinical manifestations of a malformation affecting the embryonic ectoderm. They appear as linear verrucous lesions and are more often located in the skin of the trunk or the extremities. Rarely, verrucous lesions affect the oral mucosa. Epidermal nevi can be a component of epidermal nevus syndrome (ENS), which is characterized by malformations involving several organs, such as the central nervous system. ENS is rarely associated with other solid tumors. We present the case of a patient affected by ENS who developed maxillary and mandibular ameloblastomas. Epidermal nevi were located in the left middle and lower third of the face and in the left cervical region, whereas the ameloblastomas arose within the left maxillary mucosa and within the left mandibular ramus. Features of the syndrome are described and the relevant literature is reviewed.

Epidermal nevus syndrome

Epidermal nevus syndrome (ENS) is an inclusive term for a heterogeneous group of congenital disorders characterized by the presence of epidermal nevi associated with systemic involvement. These disorders, as are all primary neurocutaneous syndromes, are neurocristopathies. The epidermal nevi that follow the lines of Blaschko and most systemic anomalies in skeletal, ocular, cardiovascular, endocrine, and orodental tissues, as well as lipomas, are due to defective neural crest. The most important and frequent anomaly in the brain in all forms of epidermal nevus syndromes (ENSs) is hemimegalencephaly (HME). This malformation often is not recognized, despite being the principal cause of neurological manifestations in ENSs. They consist mainly of epilepsy and developmental delay or intellectual disability. The onset of epilepsy in ENS usually is in early infancy, often as infantile spasms. Several syndromic forms have been delineated. I propose the term "Heide's syndrome" for those distinctive cases with the typical triad of hemifacial epidermal nevus, ipsilateral facial lipoma, and hemimegalencephaly. Most ENSs are sporadic. The mechanism is thought to be genetic mosaicism with a lethal autosomal dominant gene. Specific genetic mutations (PTEN, FGFR3, PIK3CA, and AKT1) have been documented in some patients. The large number of contributors for over more than a century and a half to the description of these disorders precludes the use of new author eponyms.

Mosaic RASopathies

"RASopathies" are a group of developmental syndromes with partly overlapping clinical symptoms that are caused by germline mutations of genes within the Ras/MAPK signaling pathway. Mutations affecting this pathway can also occur in a mosaic state, resulting in congenital syndromes often distinct from those generated by the corresponding germline mutations. For syndromes caused by mosaic mutations of the Ras/MAPK signaling pathway, the term "mosaic RASopathies" has been proposed. In the following article, genetic and phenotypic aspects of mosaic RASopathies will be discussed.