White sponge nevus (WSN) is a rare autosomal dominant disorder of the non-cornifying squamous epithelia. The clinical hallmarks are white, soft, spongy, thickened plaques on both sides of the oral mucosa and tongue. The mucous membranes of the nose, esophagus, genitalia and rectum may also be involved. Light microscopic examination usually reveals epithelial thickening, parakeratosis, extensive vacuolization of the suprabasal keratinocytes and compact aggregates of keratin intermediate filaments in the upper spinous layers. The disorder usually manifests with whitish mucosal plaques during infancy or early childhood and may be difficult to differentiate from mucosal yeast infections.