White sponge nevus presenting as genital lesions in a 28-year-old female.

A case is presented of white plaques occurring predominantly on the vulvar mucosa of a 28-year-old female diagnosed as white sponge nevus (WSN). WSN is a rare, autosomal dominant disorder involving mucous membranes. It predominantly affects the oral mucosa; however, it has been reported to rarely involve extraoral mucosal sites. In this case, histology and family history were key features leading to the correct diagnosis. WSN is an extremely rare cause of vulvar leukoplakia, yet it is important to recognize to allow for appropriate genetic counseling of this autosomal dominant disorder and to avoid misdiagnosis and the potential for subsequent exposure to ineffective treatment modalities.