White sponge nevus: a case report

White sponge nevus (WSN) is a rare hereditary dyskeratotic hyperplasia of mucous membranes. It is an autosomal dominant disorder with variable penetrance. We report a case of WSN in a healthy 21-year-old male with no history of familial involvement. A white smooth plaque with no erythema or other structural abnormalities was observed, which confirmed the diagnosis of WSN histopathologically.