{{Short description|A genetic condition affecting the mucous membranes}}
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| synonyms = '''White sponge naevus''', '''Cannon's disease''', '''Hereditary leukokeratosis of mucosa''', '''White sponge nevus of Cannon''', '''Familial white folded dysplasia''',<ref name=omim>{{OMIM|193900}}</ref><ref name="Bolognia">{{cite book |author1=Rapini, Ronald P. |author2=Bolognia, Jean L. |author3=Jorizzo, Joseph L. |title=Dermatology: 2-Volume Set |publisher=Mosby |location=St. Louis |year=2007 |pages=709, 734, 738, 740 |isbn=978-1-4160-2999-1 |oclc= |doi= |accessdate=}}</ref> or '''Oral epithelial nevus'''<ref name="Soames 1999">{{cite book|last=Soames|first=JV|title=Oral pathology|year=1999|publisher=Oxford Univ. Press|location=Oxford [u.a.]|isbn=978-0192628947|pages=141|edition=3rd|author2=Southam, J.C. }}</ref>
| image = Autosomal dominant - en.svg
| caption = White sponge nevus has an autosomal dominant pattern of inheritance.
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<!-- previous ICD10 was listed as D10, typed white sponge nevus into ICD10 search and got Q38.6
... -->
'''White sponge nevus''' WSN, is an [[autosome|autosomal]] [[Dominance (genetics)|dominant]]<ref name="pmid11379896"/> condition of the [[oral mucosa]] (the [[mucous membrane]] lining of the mouth). It is caused by a mutations in certain genes coding for [[keratin]], which causes a defect in the normal process of [[keratinization]] of the mucosa. This results in lesions which are thick, white and velvety on the inside of the cheeks within the mouth. Usually, these lesions are present from birth or develop during childhood. The condition is entirely harmless, and no treatment is required.
==Signs and symptoms==
==White sponge nevus==
It presents itself in the [[mouth]], most frequently as a thick, bilateral, symmetrical white [[Plaque (dermatology)#Primary lesions|plaques]] with a spongy, corrugated or velvety texture. Most usually, the lesions are on the buccal mucosa, but sometimes on the labial mucosa, [[alveolar ridge]], floor of the mouth, ventral surface of the tongue or soft palate. The [[gingival margin]] and dorsum of the tongue are almost never affected. Less commonly, sites outside the mouth are affected, including the [[nasal cavity|nasal]], [[esophagus|esophageal]], [[larynx|laryngeal]], anal and genital mucosae.<ref name="OMF pathology textbook" /> It usually is present from birth, or develops during childhood. Rarely, the lesions may develop during adolescence. Apart from the appearance of the affected areas, there are usually no other signs or symptoms.<ref name="OMF pathology textbook" />
[[File:Autosomal_dominant_-_en.svg|thumb|right|Diagram of autosomal dominant inheritance]]
'''White sponge nevus''' (WSN) is a rare genetic disorder characterized by the presence of white, spongy plaques on the mucous membranes, primarily affecting the [[oral cavity]]. It is a benign condition that typically presents in childhood or adolescence.
==Pathophysiology==
==Etiology==
White sponge nevus is caused by mutations in the [[keratin]] genes, specifically [[KRT4]] and [[KRT13]], which are responsible for the structural integrity of epithelial cells in the mucous membranes. The condition follows an [[autosomal dominant]] pattern of inheritance, meaning that a single copy of the mutated gene from an affected parent can cause the disorder in offspring.
WSN is caused by a mutation of the [[keratin 4]] or [[keratin 13]] genes,<ref name="pmid11379896">{{cite journal |vauthors=Terrinoni A, Rugg EL, Lane EB, etal |title=A novel mutation in the keratin 13 gene causing oral white sponge nevus |journal=J. Dent. Res. |volume=80 |issue=3 |pages=919–923 |date=Mar 2001 |pmid=11379896 |doi= 10.1177/00220345010800031401}}</ref><ref name="pmid16858417">{{cite journal |vauthors=McGowan KA, Fuchs H, Hrabé de Angelis M, Barsh GS |title=Identification of a Keratin 4 mutation in a chemically induced mouse mutant that models white sponge nevus |journal=J. Invest. Dermatol. |volume=127 |issue=1 |pages=60–64 |date=Jan 2007 |pmid=16858417 |doi=10.1038/sj.jid.5700498}}</ref> located respectively at human [[chromosome]]s [[chromosome 12 (human)|12q13]]<ref>{{OMIM|123940}}</ref> and [[chromosome 17 (human)|17q21-q22]].<ref>{{OMIM|148065}}</ref> The condition is inherited in an autosomal dominant manner.<ref name="pmid11379896"/> This indicates that the defective gene responsible for a disorder is located on an [[autosome]] (chromosomes 12 and 17 are autosomes), and only one copy of the defective gene is sufficient to cause the disorder, when inherited from a parent who has the disorder.
==Clinical presentation==
The most common manifestation of white sponge nevus is the appearance of white, thickened, and spongy plaques on the [[buccal mucosa]], although other areas such as the [[gingiva]], [[tongue]], and [[floor of the mouth]] may also be involved. These lesions are usually asymptomatic, but some patients may experience mild irritation or discomfort.
==Diagnosis==
==Diagnosis==
it is often mistaken for [[leukoplakia]].
Diagnosis of white sponge nevus is primarily clinical, based on the characteristic appearance of the lesions. A [[biopsy]] may be performed to confirm the diagnosis, revealing hyperparakeratosis and acanthosis of the epithelium. Genetic testing can identify mutations in the KRT4 or KRT13 genes, providing a definitive diagnosis.
===Classification===
The [[ICD-10]] lists WSN under "other congenital malformations of mouth". It could be classified as a [[skin disease|skin condition]],<ref name="Andrews">{{cite book |author1=James, William D. |author2=Berger, Timothy G. |title=Andrews' Diseases of the Skin: Clinical Dermatology |publisher=Saunders Elsevier |location= |year=2006 |isbn=978-0-7216-2921-6 |oclc= |doi= |page=807|display-authors=etal}}</ref> or more precisely as a [[genodermatosis]] (a genetically determined skin disorder).<ref name="OMF pathology textbook">{{cite book|last=Bouquot|first=Brad W. Neville, Douglas D. Damm, Carl M. Allen, Jerry E.|title=Oral & maxillofacial pathology|year=2002|publisher=W.B. Saunders|location=Philadelphia|isbn=978-0721690032|pages=645–646|edition=2.}}</ref>
==Treatment ==
==Management==
There is no treatment, but because this is a benign condition with no serious clinical complications, prognosis is excellent.
There is no specific treatment required for white sponge nevus, as it is a benign condition. Management focuses on reassurance and monitoring for any changes in the lesions. In cases where the lesions cause significant discomfort, topical treatments or surgical removal may be considered.
== See also ==
==Prognosis==
* [[Oral melanosis]]
The prognosis for individuals with white sponge nevus is excellent, as the condition does not predispose to malignancy or other serious complications. The lesions typically persist throughout life but do not usually cause significant health issues.
* [[List of cutaneous conditions caused by mutations in keratins]]
White sponge nevus (WSN) is a rare genetic disorder characterized by the presence of white, spongy plaques on the mucous membranes, primarily affecting the oral cavity. It is a benign condition that typically presents in childhood or adolescence.
Etiology
White sponge nevus is caused by mutations in the keratin genes, specifically KRT4 and KRT13, which are responsible for the structural integrity of epithelial cells in the mucous membranes. The condition follows an autosomal dominant pattern of inheritance, meaning that a single copy of the mutated gene from an affected parent can cause the disorder in offspring.
Clinical presentation
The most common manifestation of white sponge nevus is the appearance of white, thickened, and spongy plaques on the buccal mucosa, although other areas such as the gingiva, tongue, and floor of the mouth may also be involved. These lesions are usually asymptomatic, but some patients may experience mild irritation or discomfort.
Diagnosis
Diagnosis of white sponge nevus is primarily clinical, based on the characteristic appearance of the lesions. A biopsy may be performed to confirm the diagnosis, revealing hyperparakeratosis and acanthosis of the epithelium. Genetic testing can identify mutations in the KRT4 or KRT13 genes, providing a definitive diagnosis.
Management
There is no specific treatment required for white sponge nevus, as it is a benign condition. Management focuses on reassurance and monitoring for any changes in the lesions. In cases where the lesions cause significant discomfort, topical treatments or surgical removal may be considered.
Prognosis
The prognosis for individuals with white sponge nevus is excellent, as the condition does not predispose to malignancy or other serious complications. The lesions typically persist throughout life but do not usually cause significant health issues.
