What is white sponge nevus and how does it present in the mouth?

White sponge nevus appears as thick, white, velvety patches on the oral mucosa, most often on the inner cheeks, tongue, or floor of the mouth. The lesions are usually painless, non‑bleeding, and may grow slowly over time. They are benign but can be cosmetically concerning.

Is white sponge nevus contagious or does it require any special precautions?

No, white sponge nevus is a genetic condition and is not contagious. No special infection control measures are needed beyond routine dental hygiene practices.

How can a dentist or doctor differentiate white sponge nevus from other white oral lesions?

clinical exam is usually sufficient, but a biopsy can confirm the diagnosis. Histology shows hyperparakeratosis and a spongy appearance of the epithelium with no atypia. Unlike leukoplakia or lichen planus, white sponge nevus lacks inflammation or dysplasia.

What management strategies are available for patients with white sponge nevus, and can the lesions be removed?

Because the lesions are benign, treatment is usually not required unless they cause discomfort or cosmetic concern. Gentle oral hygiene, avoiding irritants, and regular dental check‑ups are recommended. Surgical excision or laser removal can be performed if the patient desires, but recurrence is common because the underlying genetic defect remains.

KRT13 gene

The KRT13 gene encodes keratin 13, a structural protein essential for the integrity of mucosal linings throughout the body. Mutations in this gene can lead to white sponge nevus, a benign but noticeable oral condition.

Normal Function

The KRT13 gene provides instructions for making a protein called keratin 13. Keratins are a group of tough, fibrous proteins that form the structural framework of epithelial cells, which are cells that line the surfaces and cavities of the body. Keratin 13 is found in the moist lining (mucosae) of the mouth, nose, esophagus, genitals, and anus.

Keratin 13 partners with a similar protein, keratin 4 (produced from the KRT4 gene), to form molecules known as intermediate filaments. These filaments assemble into strong networks that provide strength and resilience to the different mucosae. Networks of intermediate filaments protect the mucosae from being damaged by friction or other everyday physical stresses.

Health Conditions Related to Genetic Changes

White sponge nevus

At least five KRT13 gene mutations have been found to cause white sponge nevus, a condition that results in the formation of white patches of tissue called nevi (singular: nevus) that appear as thickened, velvety, sponge-like tissue. These nevi most often occur on the mouth (oral) mucosa (plural: mucosae). Rarely, white sponge nevus occurs on the mucosae of the nose, esophagus, genitals, or anus.

The KRT13 gene mutations that cause white sponge nevus disrupt the structure of keratin 13. As a result, keratin 13 does not fit together properly with keratin 4, leading to the formation of irregular intermediate filaments that are easily damaged with little friction or trauma. Fragile intermediate filaments in the oral mucosa might be damaged when eating or brushing one's teeth. Damage to intermediate filaments leads to inflammation and promotes the abnormal growth and division (proliferation) of epithelial cells, causing the mucosae to thicken and resulting in white sponge nevus.

Other Names for This Gene

CK-13
CK13
cytokeratin 13
cytokeratin-13
K13
K1C13_HUMAN
keratin 13, type I
keratin, type I cytoskeletal 13
keratin-13

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Tests of KRT13

Scientific Articles on PubMed

PubMed

Catalog of Genes and Diseases from OMIM

KERATIN 13, TYPE I; KRT13

Gene and Variant Databases

NCBI Gene
ClinVar

References

Nishizawa A, Nakajima R, Nakano H, Sawamura D, Takayama K, Satoh T, Yokozeki H. A de novo missense mutation in the keratin 13 gene in oral white sponge naevus. Br J Dermatol. 2008 Sep;159(4):974-5. doi:10.1111/j.1365-2133.2008.08716.x. Epub 2008 Jul 4. No abstract available. Citation on PubMed
Rugg E, Magee G, Wilson N, Brandrup F, Hamburger J, Lane E. Identification of two novel mutations in keratin 13 as the cause of white sponge naevus. Oral Dis. 1999 Oct;5(4):321-4. doi:10.1111/j.1601-0825.1999.tb00097.x. Citation on PubMed
Shibuya Y, Zhang J, Yokoo S, Umeda M, Komori T. Constitutional mutation of keratin 13 gene in familial white sponge nevus. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Nov;96(5):561-5. doi:10.1016/s1079-2104(03)00372-x. Citation on PubMed

Genomic Location

The KRT13 gene is found on chromosome 17.

MEDICAL ENCYCLOPEDIA

Genes
Genetics

Understanding Genetics

What is DNA?
What is a gene?
What is a gene variant and how do variants occur?

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