Identification of Codon 146 KRAS Variants in Isolated Epidermal Nevus and Multiple Lesions in Oculoectodermal Syndrome: Confirmation of the Phenotypic Continuum of Mosaic RASopathies.

Mosaic RASopathies are a molecularly heterogeneous group of (neuro)cutaneous syndromes with high phenotypical variability. Postzygotic variants in KRAS have been described in oculoectodermal syndrome (OES), encephalocraniocutaneous lipomatosis (ECCL) and epidermal nevus syndrome (ENS). This study confirms the continuum of mosaic neurocutaneous RASopathies showing codon 146 KRAS variants in an individual with OES and, for the first time, in an individual with (isolated) epidermal nevus. The presence of a nevus psiloliparus in individuals with OES indicates that this finding is not specific for ECCL and highlights the phenotypical overlap between ECCL and OES. The presence of the somatic KRAS variant in the nevus psiloliparus resolves the underlying molecular etiology of this fatty-tissue nevus. In addition, this finding refutes the theory of non-allelic twin-spotting as an underlying hypothesis to explain the concurrent presence of two different mosaicisms in one individual. The identification of codon 146 KRAS variants in isolated epidermal nevus introduces a new hot spot for this condition, which is useful for increasing molecular genetic testing using targeted gene sequencing panels.

Biologicals for moderate-to-severe plaque type psoriasis in pediatric patients.

INTRODUCTION: Psoriasis affects around 2% of children in Europe. The majority of cases is readily managed with topical treatments using corticosteroids without or with calcipotriol. More resistant and extensive moderate-to-severe cases require UVA or UVB phototherapies or conventional systemic treatment including ciclosporin, acitretin and methotrexate. However, these therapies are associated with a low tolerability and potential cumulative long-term adverse effects and toxicities. AREAS COVERED: About 15 years ago, the first biological appeared for the treatment of moderate-to-severe plaque type psoriasis in adult patients. Several years later, the first biologic treatment to be approved in children was etanercept, a soluble receptor that binds both tumor necrosis factor (TNF)-α and ß followed by adalimumab, a monoclonal antibody against TNF-α, and currently by ustekinumab, a monoclonal IL12/23 p40 antagonist and, very recently, secukinumab and ixekizumab, both IL17 antagonists. All these biologic treatments brought significantly improved treatment results compared to light-based therapies and conventional treatments and present very good tolerance and safety profiles. EXPERT OPINION: Due to their excellent efficacy and safety profiles ustekinumab, secukinumab and ixekizumab could currently be considered as a first-line treatment options for moderate-to-severe childhood and adolescent psoriasis requiring a systemic treatment.

Cutaneous Manifestations in Biological-Treated Inflammatory Bowel Disease Patients: A Narrative Review.

The biologic era has greatly improved the treatment of Crohn's disease and ulcerative colitis. Biologics can however induce a wide variety of skin eruptions, especially those targeting the TNF-α and Th17 pathway. These include infusion reactions, eczema, psoriasis, lupus, alopecia areata, vitiligo, lichenoid reactions, granulomatous disorders, vasculitis, skin cancer, and cutaneous infections. It is important to recognize these conditions as treatment-induced adverse reactions and adapt the treatment strategy accordingly. Some conditions can be treated topically while others require cessation or switch of the biological therapy. TNF-α antagonists have the highest rate adverse skin eruptions followed by ustekinumab and anti-integrin receptor blockers. In this review, we provide an overview of the most common skin eruptions which can be encountered in clinical practice when treating IBD (Inflammatory bowel disease) patients and propose a therapeutic approach for each condition.

Homozygous NLRP1 gain-of-function mutation in siblings with a syndromic form of recurrent respiratory papillomatosis.

Juvenile-onset recurrent respiratory papillomatosis (JRRP) is a rare and debilitating childhood disease that presents with recurrent growth of papillomas in the upper airway. Two common human papillomaviruses (HPVs), HPV-6 and -11, are implicated in most cases, but it is still not understood why only a small proportion of children develop JRRP following exposure to these common viruses. We report 2 siblings with a syndromic form of JRRP associated with mild dermatologic abnormalities. Whole-exome sequencing of the patients revealed a private homozygous mutation in NLRP1, encoding Nucleotide-Binding Domain Leucine-Rich Repeat Family Pyrin Domain-Containing 1. We find the NLRP1 mutant allele to be gain of function (GOF) for inflammasome activation, as demonstrated by the induction of inflammasome complex oligomerization and IL-1ß secretion in an overexpression system. Moreover, patient-derived keratinocytes secrete elevated levels of IL-1ß at baseline. Finally, both patients displayed elevated levels of inflammasome-induced cytokines in the serum. Six NLRP1 GOF mutations have previously been described to underlie 3 allelic Mendelian diseases with differing phenotypes and modes of inheritance. Our results demonstrate that an autosomal recessive, syndromic form of JRRP can be associated with an NLRP1 GOF mutation.

Defining the Clinical, Molecular and Ultrastructural Characteristics in Occipital Horn Syndrome: Two New Cases and Review of the Literature.

Occipital horn syndrome (OHS) is a rare connective tissue disorder caused by pathogenic variants in ATP7A, encoding a copper transporter. The main clinical features, including cutis laxa, bony exostoses, and bladder diverticula are attributed to a decreased activity of lysyl oxidase (LOX), a cupro-enzyme involved in collagen crosslinking. The absence of large case series and natural history studies precludes efficient diagnosis and management of OHS patients. This study describes the clinical and molecular characteristics of two new patients and 32 patients previously reported in the literature. We report on the need for long-term specialized care and follow-up, in which MR angiography, echocardiography and spirometry should be incorporated into standard follow-up guidelines for OHS patients, next to neurodevelopmental, orthopedic and urological follow-up. Furthermore, we report on ultrastructural abnormalities including increased collagen diameter, mild elastic fiber abnormalities and multiple autophagolysosomes reflecting the role of lysyl oxidase and defective ATP7A trafficking as pathomechanisms of OHS.

Arterial tortuosity syndrome: 40 new families and literature review.

PURPOSE: We delineate the clinical spectrum and describe the histology in arterial tortuosity syndrome (ATS), a rare connective tissue disorder characterized by tortuosity of the large and medium-sized arteries, caused by mutations in SLC2A10. METHODS: We retrospectively characterized 40 novel ATS families (50 patients) and reviewed the 52 previously reported patients. We performed histology and electron microscopy (EM) on skin and vascular biopsies and evaluated TGF-ß signaling with immunohistochemistry for pSMAD2 and CTGF. RESULTS: Stenoses, tortuosity, and aneurysm formation are widespread occurrences. Severe but rare vascular complications include early and aggressive aortic root aneurysms, neonatal intracranial bleeding, ischemic stroke, and gastric perforation. Thus far, no reports unequivocally document vascular dissections or ruptures. Of note, diaphragmatic hernia and infant respiratory distress syndrome (IRDS) are frequently observed. Skin and vascular biopsies show fragmented elastic fibers (EF) and increased collagen deposition. EM of skin EF shows a fragmented elastin core and a peripheral mantle of microfibrils of random directionality. Skin and end-stage diseased vascular tissue do not indicate increased TGF-ß signaling. CONCLUSION: Our findings warrant attention for IRDS and diaphragmatic hernia, close monitoring of the aortic root early in life, and extensive vascular imaging afterwards. EM on skin biopsies shows disease-specific abnormalities.

Pathologic Evaluation of Skin Tumors With Ex Vivo Dermoscopy With Derm Dotting.

IMPORTANCE: Ex vivo dermoscopy (EVD) with derm dotting (DD) improves clinicopathologic correlation and the quality of diagnosis in skin tumors. OBJECTIVE: To compare the diagnostic performance of the standard method of skin biopsy processing with the practice of EVD with DD. DESIGN, SETTING, AND PARTICIPANTS: This retrospective study compares the diagnostic performance in 6526 skin biopsy specimens examined from 2008 to 2010 with a standard method of processing with 8584 biopsy specimens examined in 2015 with EVD and DD. Data were analyzed from January 1 to March 31, 2016. A total of 15 110 skin biopsy specimens were included. The biopsy specimens from 2008 to 2010 were processed in a hospital-based general pathology laboratory; the biopsy specimens from 2015 were processed in a private dermatopathology laboratory. Biopsy specimens from both periods were diagnosed by the same dermatopathologist. MAIN OUTCOMES AND MEASURES: The primary outcome measures were clinicopathological characteristics, usefulness of EVD with DD, and turnaround times (TATs). RESULTS: Use of EVD with DD increased the detection of positive section margins in nonmelanoma skin cancer from 8.4% to 12.8%. The most significant increase was seen in Bowen disease, invasive squamous cell carcinoma, and a superficial type of basal cell carcinoma (BCC). With EVD and DD, a specific clinicopathologic diagnosis was made in 27.7% of nevi compared with only 10.3% using the standard method. The incidence of moderately and severely dysplastic nevi increased from 1.0% to 7.2% and from 0.6% to 1.4%, respectively. The detection of ulceration in melanomas with thicker than 1 mm increased from 24.0% to 31.3%. The number of nevi-associated melanomas increased from 15.5% to 33.3%. The number of collision lesions from 0.07% to 1.07%. The TAT for nevi decreased from 2 days to 1 day, for melanomas from 5 days to 2 days, and for BCC from 2 days to 1 day. CONCLUSIONS AND RELEVANCE: Ex vivo dermoscopy and DD with adapted sectioning in a dermatopathology setting allows a more accurate and less time consuming histopathologic diagnosis of skin tumors. These findings suggest that pathologists involved in skin tumor evaluation should be encouraged to learn dermoscopy and replace random transverse cutting with lesion-specific and DD-guided cutting.

Total-Body Examination vs Lesion-Directed Skin Cancer Screening.

IMPORTANCE: Skin cancer is the most frequent cancer type. It remains unknown if and how screening programs can be organized in a cost-effective manner. OBJECTIVE: To compare the 2 screening strategies of systematic total-body examination (TBE) and lesion-directed screening (LDS), with a focus on the participation rate, detection rate, anxiety, and cost. DESIGN, SETTING, AND PARTICIPANTS: Population-based cross-sectional screenings by a team of 6 dermatologists were organized in 2 sociodemographically similar regions. The TBE was organized in a community of 9325 inhabitants 18 years and older (Wichelen, East Flanders, Belgium) during a 5-day screening (March 14-18, 2014). The LDS was organized in a sociodemographically comparable community (Nevele, East Flanders, Belgium) of 9484 adult inhabitants during a 4-day screening (April 22 and 25-27, 2014). The first population received a personal invitation for a standard TBE. In the second population, individuals were invited for an LDS if they had a lesion meeting 1 or more of the following criteria: ABCD rule (A, asymmetry; B, borders; C, colors; and D, differential structures), ugly duckling sign, new lesion lasting longer than 4 weeks, or red nonhealing lesions. MAIN OUTCOMES AND MEASURES: In total, 1982 individuals were screened, and 47 skin cancers (2.4%) were histologically confirmed, including 9 melanomas (0.5%), 37 basal cell carcinomas (1.9%), and 1 squamous cell carcinoma or Bowen disease (0.1%). RESULTS: The positive predictive value for all suspicious lesions was 56.6% (47 of 83). The participation rate was 17.9% (1668 of 9325) in the TBE group vs 3.3% (314 of 9484) in the LDS group (P < .01). The skin cancer detection rate per 100 participants did not differ significantly between the 2 groups, with rates of 2.3% (39 of 1668) in the TBE group vs 3.2% (8 of 248) in the LDS group (P = .40). The operational effectiveness per 100 invitees was 0.4% (39 of 9325) in the TBE group vs 0.1% (8 of 9484) in the LDS group (P < .01). In addition, LDS was 5.6 times less time consuming than TBE. Participants in the LDS group had significantly higher baseline anxiety levels compared with participants in the TBE group (3.7 vs 3.3 points on a visual analog scale, P < .01). In screenees without a suspicious lesion, anxiety levels significantly dropped after screening. CONCLUSIONS AND RELEVANCE: Total-body examination yielded a higher absolute number of skin cancers. Lesion-directed screening had a similar detection rate of 3.2% (8 of 248) but was 5.6 times less time consuming. When performed by dermatologists, LDS is an acceptable alternative screening method in health care systems with limited budgets or long waiting lists.

NF1 loss induces senescence during human melanocyte differentiation in an iPSC-based model.

Neurofibromatosis type 1 (NF1) is a frequent genetic disease leading to the development of Schwann cell-derived neurofibromas or melanocytic lesions called café-au-lait macules (CALMs). The molecular mechanisms involved in CALMs formation remain largely unknown. In this report, we show for the first time pathophysiological mechanisms of abnormal melanocyte differentiation in a human NF1(+/-) -induced pluripotent stem cell (iPSC)-based model. We demonstrate that NF1 patient-derived fibroblasts can be successfully reprogrammed in NF1(+/-) iPSCs with active RAS signaling and that NF1 loss induces senescence during melanocyte differentiation as well as in patient's-derived CALMs, revealing a new role for NF1 in the melanocyte lineage.

Hypomelanoses in children.

Hypomelanosis of the skin is a frequently encountered problem in childhood, being totally innocent or representing the first sign of a multisystem disorder. Medical history, clinical examination, Wood's light investigation, histological analysis of the skin and a multidisciplinary consultation can contribute to a correct and early diagnosis of the different types of hypopigmentations. In the present paper, we present a systematic clinical approach to the differential diagnosis of those skin disorders.

In vivo vitiligo induction and therapy model: double-blind, randomized clinical trial.

In this study, we developed an in vivo vitiligo induction model to explore the underlying mechanisms leading to Koebner's phenomenon and to evaluate the efficacy of therapeutic strategies. The model consisted of 12 pigmented test regions on the back of generalized vitiligo patients that were exposed to three Koebner induction methods: cryotherapy, 755 nm laser therapy, and epidermal abrasion. In addition, four cream treatments (pimecrolimus, tacrolimus, steroid and placebo) were randomly applied. Koebnerization was efficiently induced by all three induction methods. In general, cryotherapy was the best method of Koebner induction, followed by 755 nm laser therapy and epidermal abrasion. Reproducible results were obtained, which showed enhanced depigmented surface areas and higher amounts of T lymphocytes in placebo-treated test zones compared to active treated areas. Tacrolimus and local steroids were better inhibitors of Koebner's process (P < 0.05) compared to pimecrolimus. Our in vivo vitiligo induction model is very informative to investigate vitiligo induction and to determine the efficacy of topical treatments in vitiligo. This proof of concept confirms the efficient comparison of head-to-head therapeutic strategies intra-individually in a standardized, specific and better timed way.

First histopathological and immunophenotypic analysis of early dynamic events in a patient with segmental vitiligo associated with halo nevi.

Segmental vitiligo is often ascribed to the neurogenic theory of melanocyte destruction, although data about the initial etiopathological events are scarce. Clinical, histopathological and T-cell phenotypic analyses were performed during the early onset of a segmental vitiligo lesion in a patient with associated halo nevi. Histopathological analysis revealed a lymphocytic infiltrate, mainly composed of CD8+ T-cells and some CD4(+) T-cells around the dermo-epidermal junction. Flow cytometry analysis of resident T-cells revealed a clear enrichment of pro-inflammatory IFN-gamma producing CD8+ T-cells in lesional skin compared to the non-lesional skin. Using human leukocyte antigen-peptide tetramers (MART-1, tyrosinase, gp100), increased numbers of T cells, recognizing melanocyte antigens were found in segmental vitiligo lesional skin, as compared with the non-lesional skin and the blood. Our findings indicate that a CD8+ melanocyte specific T cell-mediated immune response, as observed in generalized vitiligo, also plays a role in segmental vitiligo with associated halo nevi.

Molecular dissection of isolated disease features in mosaic neurofibromatosis type 1.

Elucidation of the biological framework underlying the development of neurofibromatosis type 1 (NF1)-related symptoms has proved to be difficult. Complicating factors include the large size of the NF1 gene, the presence of several NF1 pseudogenes, the complex interactions between cell types, and the NF1-haploinsufficient state of all cells in the body. Here, we investigate three patients with distinct NF1-associated clinical manifestations (neurofibromas only, pigmentary changes only, and association of both symptoms). For each patient, various tissues and cell types were tested with comprehensive and quantitative assays capable of detecting low-percentage NF1 mutations. This approach confirmed the biallelic NF1 inactivation in Schwann cells in neurofibromas and, for the first time, demonstrated biallelic NF1 inactivation in melanocytes in NF1-related cafe-au-lait macules. Interestingly, both disease features arise even within a background of predominantly NF1 wild-type cells. Together, the data provide molecular evidence that (1) the distinct clinical picture of the patients is due to mosaicism for the NF1 mutation and (2) the mosaic phenotype reflects the embryonic timing and, accordingly, the neural crest-derived cell type involved in the somatic NF1 mutation. The study of the affected cell types provides important insight into developmental concepts underlying particular NF1-related disease features and opens avenues for improved diagnosis and genetic counseling of individuals with mosaic NF1.

Germline loss-of-function mutations in SPRED1 cause a neurofibromatosis 1-like phenotype.

We report germline loss-of-function mutations in SPRED1 in a newly identified autosomal dominant human disorder. SPRED1 is a member of the SPROUTY/SPRED family of proteins that act as negative regulators of RAS->RAF interaction and mitogen-activated protein kinase (MAPK) signaling. The clinical features of the reported disorder resemble those of neurofibromatosis type 1 and consist of multiple café-au-lait spots, axillary freckling and macrocephaly. Melanocytes from a café-au-lait spot showed, in addition to the germline SPRED1 mutation, an acquired somatic mutation in the wild-type SPRED1 allele, indicating that complete SPRED1 inactivation is needed to generate a café-au-lait spot in this syndrome. This disorder is yet another member of the recently characterized group of phenotypically overlapping syndromes caused by mutations in the genes encoding key components of the RAS-MAPK pathway. To our knowledge, this is the first report of mutations in the SPRY (SPROUTY)/SPRED family of genes in human disease.

Comprehensive NF1 screening on cultured Schwann cells from neurofibromas.

Neurofibromatosis type 1 (NF1) is mainly characterized by the occurrence of benign peripheral nerve sheath tumors or neurofibromas. Thorough investigation of the somatic mutation spectrum has thus far been hampered by the large size of the NF1 gene and the considerable proportion of NF1 heterozygous cells within the tumors. We developed an improved somatic mutation detection strategy on cultured Schwann cells derived from neurofibromas and investigated 38 tumors from nine NF1 patients. Twenty-nine somatic NF1 lesions were detected which represents the highest NF1 somatic mutation detection rate described so far (76%). Furthermore, our data strongly suggest that the acquired second hit underlies reduced NF1 expression in Schwann cell cultures. Together, these data clearly illustrate that two inactivating NF1 mutations, in a subpopulation of the Schwann cells, are required for neurofibroma formation in NF1 tumorigenesis. The observed somatic mutation spectrum shows that intragenic NF1 mutations (26/29) are most prevalent, particularly frameshift mutations (12/29, 41%). We hypothesize that this mutation signature might reflect slightly reduced DNA repair efficiency as a trigger for NF1 somatic inactivation preceding tumorigenesis. Joint analysis of the current and previously published NF1 mutation data revealed a significant difference in the somatic mutation spectrum in patients with a NF1 microdeletion vs. non-microdeletion patients with respect to the prevalence of loss of heterozygosity events (0/15 vs. 41/81). Differences in somatic inactivation mechanism might therefore exist between NF1 microdeletion patients and the general NF1 population.

Somatic loss of wild type NF1 allele in neurofibromas: Comparison of NF1 microdeletion and non-microdeletion patients.

Neurofibromatosis type I (NF1) is an autosomal dominant familial tumor syndrome characterized by the presence of multiple benign neurofibromas. In 95% of NF1 individuals, a mutation is found in the NF1 gene, and in 5% of the patients, the germline mutation consists of a microdeletion that includes the NF1 gene and several flanking genes. We studied the frequency of loss of heterozygosity (LOH) in the NF1 region as a mechanism of somatic NF1 inactivation in neurofibromas from NF1 patients with and without a microdeletion. There was a statistically significant difference between these two patient groups in the proportion of neurofibromas with LOH. None of the 40 neurofibromas from six different NF1 microdeletion patients showed LOH, whereas LOH was observed in 6/28 neurofibromas from five patients with an intragenic NF1 mutation (P = 0.0034, Fisher's exact). LOH of the NF1 microdeletion region in NF1 microdeletion patients would de facto lead to a nullizygous state of the genes located in the deletion region and might be lethal. The mechanisms leading to LOH were further analyzed in six neurofibromas. In two out of six neurofibromas, a chromosomal microdeletion was found; in three, a mitotic recombination was responsible for the observed LOH; and in one, a chromosome loss with reduplication was present. These data show an important difference in the mechanisms of second hit formation in the 2 NF1 patient groups. We conclude that NF1 is a familial tumor syndrome in which the type of germline mutation influences the type of second hit in the tumors.