[A boy with white sponge naevus of the buccal mucosa]. / Een jongen met witte afwijkingen op het mondslijmvlies.

White sponge naevus (WSN) is a rare, autosomal dominant disorder that causes various complaints WSN is most commonly found on the buccal mucosa. Clinically, the white, slightly elevated lesions of WSN may be confused with other disorders on oral mucosa. We report a case of WSN in a 14-year-old boy who had complaints for a considerable period of time. WSN is caused by mutations in KRT4 and KRT13.

Chronic Oral Lesions.

Chronic oral mucosal lesions can be associated with several mucocutaneous diseases. This article reviews the autoimmune and immune-mediated, reactive, genetic, and infectious diseases that may present with chronic oral and/or cutaneous manifestations and provides a rational approach to diagnosis and management.

Keratin 13 deficiency causes white sponge nevus in mice.

White sponge nevus (WSN) is a benign autosomal dominant disorder characterized by the formation of white spongy plaques in the oral mucosa. Keratin (KRT) 13 is highly expressed in the mucosa, and mutations in this gene have been commonly associated with WSN patients. However, it remains unknown whether there is a causal relationship between KRT13 mutations and WSN and what the underlying mechanisms might be. Here, we use mouse genetic models to demonstrate that Krt13 is crucial for the maintenance of epithelial integrity. Krt13 knockout mice show a WSN-like phenotype in several tissues, including the tongue, buccal mucosa, and esophagus. Transcriptome analyses uncover that Krt13 regulates a cohort of gene networks in tongue epithelial cells, including epithelial differentiation, immune responses, stress-activated kinase signaling, and metabolic processes. We also provide evidence that epithelial cells without Krt13 are susceptible to mechanical stresses experienced during postnatal life, resulting in unbalanced cell proliferation and differentiation. These data demonstrate that Krt13 is essential for maintaining epithelial homeostasis and loss of Krt13 causes the WSN-like phenotype in mice.

Placas blancas en cavidad oral / White Plaques in the Oral Cavity

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White sponge nevus: A condition not always clinically suspected.

White sponge nevus (WSN) is an uncommon benign inherited disorder characterized by white and diffuse painless lesions in oral, esophageal, or genital mucosa. The lesions may develop at birth or later in childhood or adolescence, with careful clinical examination being sufficient for diagnosis in most cases. However, microscopic analysis may be necessary particularly in adults in which other whitish oral lesions may be clinically suspected. Dermatologists, dentists, and pathologists should consider WSN when evaluating multiple white oral lesions, thus preventing unnecessary treatments. Herein, we report four additional cases of WSN with emphasis on its clinical and histopathological features.

Paquioniquia congénita tipo I o síndrome de Jadassohn- Lewandowsky: un caso de presentación familiar / Congenital pachyonychia type I or Jadassohn-Lewandowsky syndrome: a familial case

La paquioniquia congénita es una rara genodermatosis de herencia autosómica dominante, que produce alteración de la queratinización a nivel de piel, uñas y mucosas. El primer caso fue descrito por Jadassohn y Lewandowsky en 1906, y actualmente afecta a miles de personas en el mundo. El Registro Internacional de Investigación de Paquioniquia Congénita (IPCRR, del inglés, International PC Research Registry) ha identificado a nivel mundial hasta enero de 2020, 977 individuos en 517 familias con paquioniquia congénita, confirmadas genéticamente. Esta condición es considerada en nuestro país como una enfermedad huérfana, y previamente solo hay un reporte en la literatura de un caso en 2009. Se presenta el caso clínico de un paciente masculino de 23 años de edad procedente del área rural del municipio de Timbío, Colombia, con historia clínica de distrofia ungueal hipertrófica en todas las uñas de manos y pies, queratodermia palmoplantar y dolor plantar moderado a severo. Además, presentaba leucoqueratosis oral, hiperqueratosis folicular en muslos e hiperhidrosis palmoplantar. No presentaba quistes foliculares ni antecedente de dientes natales. Sus manifestaciones clínicas se catalogaron como propias de la paquioniquia congénita tipo I. Sumado a lo anterior, se identificaron características clínicas similares en otros miembros de la familia en tres generaciones, incluidos un hermano, la madre y la abuela materna, lo cual evidenció un patrón de herencia propio de esta enfermedad.

Pachyonychia congenita is a rare genodermatosis of autosomal dominant inheritance pattern that affects keratinization at the level of skin, nails and mucous membranes. The first case was described by Jadassohn and Lewandowsky in 1906 and it affects thousands of people around the world. The International Pachyonychia Congenita Research Registry (IPCRR) has identified until January 2020, worldwide, 977 individuals in 517 families with pachyonychia congenita genetically confirmed. This condition is considered in our country as an orphan disease and there has only been one previous case report in 2009. We present a case of a 23-year old male patient from the rural area of Timbio, Colombia, with a history of hypertrophic nail dystrophy in all nails and toenails, palmoplantar keratoderma and moderate plantar pain. In addition, he presented oral leucokeratosis, follicular hyperkeratosis in the thighs, and palmoplantar hyperhidrosis. No follicular cysts were present nor history of natal teeth. Clinical manifestations were classified as typical of congenital pachyonychia type I. Furthermore, similar clinical manifestations were identified in other family members from three generations, including his brother, mother and maternal grandmother, a characteristic inheritance pattern of this illness.

The molecular-based differentiation of Heck's disease from its mimics including oral condyloma and white sponge nevus.

Heck's disease (focal or multifocal epithelial hyperplasia) is a benign, rare condition of the skin and mucous membranes induced by human papillomavirus (HPV) infection. Other entities that can induce large papillomatous lesions that involve the mucous membranes and skin include condyloma acuminatum, which is sexually transmitted, and white sponge nevus, often due to a mutation of cytokeratin 4 or 13. Six cases diagnosed as either Heck's disease (n = 2) or white sponge nevus (n = 4) and 6 oral condyloma were compared on histologic grounds and analyzed in situ for HPV DNA, including HPVs 6,11, and 13, as well as cytokeratins 4 and 13. Each case showed marked acanthosis, and para/hyperkeratosis. More variable histologic findings included rete ridge elongation, keratinocyte degeneration, and perinuclear halos. High copy HPV 13 DNA was evident in the squamous cells towards the surface in the two cases diagnosed as Heck's disease and in two cases diagnosed as white sponge nevus on clinical grounds. HPV 6/11 was found in each of the six condyloma. Marked decrease in either cytokeratin 4 or 13 was evident in the two cases diagnosed as white sponge nevus that were HPV DNA negative. It is concluded that in situ hybridization analyses including HPVs 6, 11, and 13 as well as immunohistochemistry for cytokeratins 4 and 13 can differentiate Heck's disease from condyloma and white sponge nevus, which can be difficult to differentiate on clinical and histologic grounds.

Keratin 4 regulates the development of human white sponge nevus.

BACKGROUND: The aim of this study was to investigate the roles of keratin 4 (KRT4) gene in the development of human white sponge nevus (WSN). METHODS: Transgenic mice were created using the microinjection method with pcDNA3.1 vectors expressing KRT4 wild-type (WT) gene and E520K mutation. Polymerase chain reaction (PCR) and Western blotting were used to identify the genotype of transgenic founders and their filial generations. Expression of KRT4 in mouse oral mucosa was characterized by immunohistochemistry (IHC), and the whole epithelium layer of transgenic mice was observed using transmission electron microscope (TEM). RESULTS: The positive rate of KRT4 transgenic mice in F1 generation was 45.5%. Expression level of KRT4 protein was significantly higher in 2-month-old transgenic mice than WT mice. Furthermore, all the epithelial lamina of 3-month-old transgenic mice showed reduced staining of KRT4. The surface and spinous layers were full of hyalocytes and bubble cells, which are similar to the clinical symptoms of WSN. For the ultrastructure, both tonofilaments and Odland bodies increased. CONCLUSIONS: Our study indicated the mutated KRT4 gene may play important roles in the pathogenesis of WSN.

Clinical features and molecular genetic analysis in a Turkish family with oral white sponge nevus.

BACKGROUND: Oral white sponge nevus (WSN) is a rare autosomal dominant benign condition, characterized by asymptomatic spongy white plaques. Mutations in Keratin 4 (KRT4) and 13 (KRT13) have been shown to cause WSN. Familial cases are uncommon due to irregular penetrance. Thus, the aim of the study was: a) to demonstrate the clinical and histopathological features of a three-generation Turkish family with oral WSN b) to determine whether KRT4 or KRT13 gene mutation was the molecular basis of WSN. MATERIAL AND METHODS: Out of twenty members of the family ten were available for assessment. Venous blood samples from six affected and five unaffected members and 48 healthy controls were obtained for genetic mutational analysis. Polymerase chain reaction was used to amplify all exons within KRT4 and KRT13 genes. These products were sequenced and the data was examined for mutations and polymorphisms. RESULTS: Varying presentation and severity of clinical features were observed. Analysis of the KRT13 gene revealed the sequence variant Y118D as the disease-causing mutation. One patient revealed several previously unreported polymorphisms including a novel mutation in exon 1 of the KRT13 gene and a heterozygous deletion in exon 1 of KRT4. This deletion in the KRT4 gene was found to be a common polymorphism reflecting a high allele frequency of 31.25% in the Turkish population. CONCLUSIONS: Oral WSN may manifest variable clinical features. The novel mutation found in the KRT13 gene is believed to add evidence for a mutational hotspot in the mucosal keratins. Molecular genetic analysis is required to establish correct diagnosis and appropriate genetic consultation.

Mutations in the genes for keratin-4 and keratin-13 in Swedish patients with white sponge nevus.

BACKGROUND: White sponge nevus is a rare autosomal dominant disorder that affects the non-keratinised stratified squamous epithelium. Mutations in the genes that encode mucosa-specific keratin-4 and keratin-13 are strongly linked to the manifestation of white sponge nevus. This study involved mutational analysis of the genes encoding keratin-4 and keratin-13 in two Swedish families with white sponge nevus. METHODS: The diagnosis of white sponge nevus was based on disease history, clinical characteristics of the lesions and, in the majority of the cases, histopathological examination. Samples were collected from the affected buccal mucosa using buccal swabs. DNA was subsequently extracted and amplified using touchdown-PCR. The keratin-4 and keratin-13 genes were sequenced, and a genetic analysis was performed. RESULTS: A novel heterozygous missense mutation was identified in exon 1A of the keratin-4 gene in Family 2. In addition, previously reported heterozygous missense mutations were identified in the keratin-4 (E449K, A72V, Q156R, R208H) and keratin-13 (L115P) genes in both families. CONCLUSION: We describe a novel heterozygous missense mutation in the keratin-4 gene of a Swedish family with white sponge nevus. Our results support the notion that mutations in keratin-4 and keratin-13 are the underlying cause of white sponge nevus.

White Sponge Nevus: Report of a Case and Review of the Literature.

White sponge nevus is a rare benign autosomal dominant disorder with variable penetrance. It is characterized by asymptomatic white plaques affecting mainly the oral mucosa. Careful clinical and histopathological examination is indicated to exclude other more serious conditions presenting as oral white lesions. Herein, we present a new case of oral white sponge nevus in a 17-year-old Iranian male with no familial background.

Nevo blanco esponjoso familiar / Familiar white sponge nevus

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Expression profiling of white sponge nevus by RNA sequencing revealed pathological pathways.

BACKGROUND: White sponge nevus (WSN) is a rare periodontal hereditary disease. To date, almost all WSN studies have focused on case reports or mutation reports. Thus, the mechanism behind WSN is still unclear. We investigated the pathogenesis of WSN using expression profiling. METHODS: Sequence analysis of samples from a WSN Chinese family revealed a mutation (332 T > C) in the KRT13 gene that resulted in the amino acid change Leu111Pro. The pathological pathway behind the WSN expression profile was investigated by RNA sequencing (RNA-seq). RESULTS: Construction of a heatmap revealed 24 activated genes and 57 reduced genes in the WSN patients. The ribosome structure was damaged in the WSN patients. Moreover, the translation rate was limited in the WSN patients, whereas ubiquitin-mediated proteolysis was enhanced. CONCLUSIONS: Our results suggest that the abnormal degradation of the KRT13 protein in WSN patients may be associated with keratin 7 (KRT7) and an abnormal ubiquitination process.

Current approaches to the diagnosis and treatment of white sponge nevus.

White sponge nevus (WSN) in the oral mucosa is a rare autosomal dominant genetic disease. The involved mucosa is white or greyish, thickened, folded and spongy. The genes associated with WSN include mutant cytokeratin keratin 4 (KRT4) and keratin 13 (KRT13). In recent years, new cases of WSN and associated mutations have been reported. Here, we summarise the recent progress in our understanding of WSN, including clinical reports, genetics, animal models, treatment, pathogenic mechanisms and future directions. Gene-based diagnosis and gene therapy for WSN may become available in the near future and could provide a reference and instruction for treating other KRT-associated diseases.