White sponge nevus

White sponge nevus (WSN), also known as Cannon's white sponge nevus, familial white folded mucosal dysplasia, or oral epithelial nevus, is a rare benign genetic disorder affecting the mucous membranes, most commonly the oral mucosa. It is caused by mutations in the keratin 4 (KRT4) or keratin 13 (KRT13) genes, which encode proteins essential for the structural integrity of mucosal epithelial cells. The condition is characterized by thick, white, spongy, folded or corrugated plaques that appear on the buccal mucosa (inner cheeks), though the tongue, floor of the mouth, and other mucosal surfaces may also be involved. In some cases, extraoral mucosal sites such as the nasal, esophageal, and anogenital mucosa can be affected. The lesions of white sponge nevus are typically present from birth or early childhood and tend to persist throughout life, though they may fluctuate in severity. The plaques are usually painless and asymptomatic, though some patients report a rough texture or mild discomfort. The condition is entirely benign and carries no risk of malignant transformation. The primary clinical significance lies in distinguishing WSN from other white oral lesions, including leukoplakia, oral candidiasis, lichen planus, and hereditary benign intraepithelial dyskeratosis, which may require different management. There is no definitive cure for white sponge nevus, and treatment is generally not required given its benign nature. For patients who experience cosmetic concerns or discomfort, topical treatments such as tetracycline mouth rinses or other antibiotic rinses have been reported to temporarily reduce the thickness and whiteness of the plaques, though lesions typically recur upon discontinuation. Genetic counseling may be offered to affected families to explain the inheritance pattern and benign prognosis of the condition.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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