mucous membrane disorder
White Sponge Nevus Case Report David M. Walton, B.S.; Daria Vasilyeva, D.D.S.; Louis Mandel, D.D.S.
ABSTRACT White sponge nevus (WSN) is a rare autosomal dominant asymptomatic keratotic disorder. A case report is presented of a 28-year-old male with a longstanding asymptomatic and widespread oral mucous membrane keratosis. A diagnosis of WSN was made based on his clinical history, the characteristic appearance of the lesion and the histopathology. White sponge nevus (WSN) is a rare autosomal dominant disorder. Because of its irregular penetrance, inheritance is uncommon, and most cases are seen without a familial background.[1-4] The condition is characterized by an oral mucosa that is thickened, white, corrugated, soft and spongy. It affects the non-keratinized oral mucous membrane while sparing keratinized oral tissues.[4] Most commonly, the buccal mucosa is involved bilaterally. But at times it can be involved unilaterally. The labial mucosa, tongue and mouth floor may also display the characteristic features of WSN. Extraorally, keratotic lesions have been reported in the pharynx, esophagus and anogenital areas.[2,5,6] WSN is a benign, asymptomatic disorder with no gender preference[6-8] and a reported incidence of 1:200,000.[2,6] It can be present at birth, or make its appearance in early adolescence.[1,6,9]
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APRIL 2022
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The New York State Dental Journal
Despite its asymptomatic nature, patients become concerned about the abnormal tissue texture and the cosmetic appearance of the lesion, features that persist throughout life. WSN affects the differentiation process of mucous membranes. Histologically, WSN is characterized by parakeratosis and marked intraepithelial edema and prominent thickening of the spinous layer (acanthosis). The architecture of the epithelium is preserved; no dysplasia or atypia is present; and the associated connective tissue is usually devoid of inflammation. Acanthosis is usually accompanied by a characteristic clearing of the cytoplasm of the cells in the spinous layer and the presence of eosinophilic perinuclear condensations representing aggregates of keratin tonofilaments, pathognomonic to WSN.[2,3] The development of the hyperkeratotic WSN is due to a defect in the normal keratinization of the oral mucosa. The defect has been traced to a disorder of cytokeratins (CK). The CKs consist of a family of multiple proteins that are expressed by the cytoplasm of epithelial cells. Nonkeratinizing epithelium expresses CK4 and CK13, encoded by KRT4 and KRT13 genes. Mutations in these two genes have been related to the development of WSN.[1,2,4,8,10] Case Report A 28-year-old male was referred by his dentist to the Columbia University College of Dental Medicine because of an asymptom-
