White Sponge Nevus - Causes, Symptoms, Diagnosis and Treatment

Introduction:

People sometimes wonder about the cause of the white patches inside the mouth on the inner cheeks. Well, it could be leukoplakia or candidal infections, which are common oral problems seen among adults. However, not all white patches on the mucosa are leukoplakia or infections. Some patches, which do not cause any discomfort, could have been seen since birth or early childhood, and this condition is called white sponge nevus.

What Is White Sponge Nevus?

White sponge nevus is a genetic condition that affects the mucosal lining of the mouth due to the mutation of a gene. This condition is often characterized by the formation of thick, velvety white layers of tissues in the mucosal lining of the oral cavity. In some cases, white, velvety, dense tissue formations are also seen in the mucosal lining of the genital areas. This condition can be seen from birth or during early childhood. Each velvety white patch of tissue formation is called a “nevi” (nevus is the plural form of nevi).

What Causes White Sponge Nevus?

White sponge nevus is an autosomal dominant condition. A gene mutation causes it, KRT4 (Keratin 4) or KRT13 (Keratin 13). These genes are responsible for the synthesis of a fibrous protein called keratin. This protein, keratin, strengthens the fibers of the mucosal linings of all body cavities. A mutation in either of these genes leads to the formation of an abnormal fibrous protein that is weaker than keratin. This protein often gets damaged easily during everyday activities like chewing food or brushing the teeth. This condition might run in families.

How Is White Sponge Nevus Inherited?

The inheritance pattern of this condition is autosomal dominant, where one altered gene copy in each cell can lead to the disorder. However, some individuals with the mutation causing white sponge nevus may not exhibit these abnormal growths, which is termed reduced penetrance.

Who Develops White Sponge Nevus?

White sponge nevus is considered an autosomal dominant condition, meaning children of an affected parent have a 50:50 chance of inheriting the condition. However, it can occasionally occur sporadically without any family history of the condition.

While considered rare, it may be underdiagnosed, particularly when similar lesions are absent in other family members.

The severity of symptoms varies, ranging from mild to extensive changes, and some studies suggest it affects females more frequently than males. White sponge naevus may be evident at birth or later during childhood or adolescence.

What Is the Mechanism Behind the Development of White Sponge Nevus?

White sponge nevus arises from a mutation occurring in the highly conserved regions of the 1a or 2b domains of the genes encoding keratin 4 or 13. Typically, a missense mutation occurs, altering a crucial amino acid and disrupting the assembly of intermediate filaments. These mutations primarily affect areas where keratin 4 and 13 proteins are produced, such as the oral, nasal, esophageal, and anogenital mucosae. Electron microscopy reveals abnormal aggregation of intermediate filaments in the large, clear cells associated with white sponge naevus.

What Are the Common Signs and Symptoms of White Sponge Nevus?

White sponge nevus is a very rare genetic autosomal dominant condition. That is, this condition is seen to affect less than one person in every 2,00,000 people. This condition affects both men and women equally and has not been found to affect any particular population.

Some of the common signs and symptoms of white sponge nevus are,

• The nevus (white, spongy tissue formation seen in the mucosal part of the oral cavity) is often symptomless and painless.

• These white lesions are often found bilaterally on both sides of the mouth.

• The lesions are commonly seen in the buccal mucosa (inner cheek). However, they can also be seen in the gums, upper palate, floor of the mouth, and tongue in some cases. White sponge nevus is rare in the mucosal lining of the genital areas.

• The signs are the formation of corrugated, thick lesions in the inner linings of the mouth. The texture of the lesions is velvety or spongy.

• The lesions are often seen since birth or can be more evident during early childhood.

• The lesions grow and are often seen when they reach a bigger size, as they are symptomless.

• The nevus itself does not cause any pain or discomfort. However, the thick corrugated surface of these lesions may favor the accumulation of bacteria, which can cause discomfort.

How to Diagnose White Sponge Nevus?

• The dentist or general physician often clinically diagnoses the lesion's size, shape, and texture.

• They usually rule out conditions like leukoplakia and candidiasis before diagnosing them.

• A test called genetic testing registry (GTR) is done to find any abnormal mutations in the gene.

What Are the Other Conditions That Mimic White Sponge Nevus?

Few other standard conditions of the oral cavity resemble white sponge nevus. Therefore, before starting any treatment or before making the final diagnosis, the presence of other conditions must be ruled out. Some of the common conditions that mimic white sponge nevus are,

• Candidiasis.

• Leukoplakia.

• Cheek biting habits.

• Lichen planus.

• Dental plaque.

What Are Other Names Used for White Sponge Nevus?

White sponge nevus (WSN) is called by different names such as,

• Cannon’s disease.

• Nevus of cannon.

• Familial white folded mucosal dysplasia.

• Hereditary oral keratosis.

• White gingivo stomatitis.

• White sponge nevus of cannon.

• White sponge nevus of the mucosa.

• Leukokeratosis of the oral mucosa.

• Leukokeratosis, hereditary mucosal.

How to Treat White Sponge Nevus?

White sponge nevus is an autosomal dominant condition that does not cause any severe complications. Therefore, treatment is mostly not needed to cure it.

1. In some cases, the corrugated surfaces of the white sponge nevus may lead to the formation of bacteria in the layers that could cause discomfort. In those situations, your dentist or general physician might prescribe an antibiotic and antiseptic like chlorhexidine, known to be present in mouthwashes.

2. Usage of Tetracycline for a few weeks has shown improvements.

Conclusion:

White sponge nevus is a very rare genetic autosomal dominant condition that might lead to the formation of white spongy layers of tissues in the oral cavity. Though they resemble leukoplakia or lichen planus, they do not usually cause discomfort or pain to the person with them. Therefore, 90 percent of the people affected do not seek treatment. However, further invasion of the white sponge nevus with bacteria can lead to discomfort and pain. These complications can be avoided by following a proper oral hygiene routine and using antiseptic mouthwashes with Chlorhexidine.