Non-familial White Sponge Nevus, an Innocuous yet Clinically Significant Entity: Report of a Case with Review of the Literature

White sponge nevus (WSN) is a hereditary mucosal defect that primarily affects the oral mucosa, presenting with asymptomatic velvety, corrugated hyperkeratotic white plaques that do not disappear on stretching the mucosa. In this case report, we present a non-familial case of a WSN occurring in the tongue in a middle-aged female, which was misdiagnosed as verrucous leukoplakia.

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.

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.

A novel keratin 13 variant in a four-generation family with white sponge nevus

We report a novel KRT13 germ line variant that causes white sponge nevus (WSN) with mucosal dysplasia. Genital, vaginal, and cervical WSN were observed in four female patients, of whom two had premalignant cervical lesions at young age. Two of the 12 patients with oral WSN developed oral squamous cell carcinoma.

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.

Normal variations of oral anatomy and common oral soft tissue lesions: evaluation and management

Examination of the oral cavity can provide significant diagnostic information regarding the general health of the patient. The oral cavity is affected by a multitude of pathologic conditions of variable cause and significance; however, there are numerous normal variations of oral soft tissue structures that may resemble a pathologic state. Understanding these variations assists practitioners to discriminate between normal versus abnormal findings and determine the appropriate course of management, if necessary.