An autosomal dominant disorder that is manifested by thickened spongiform ORAL MUCOSA with a white opalescent tint. Other MUCOSAL TISSUE may also be involved mucosa found in the vagina; rectum, and nasal cavity may be similarly involved. This form of LEUKOKERATOSIS can be caused by a mutation in the gene for KERATIN 4 and is not considered a PRENEOPLASTIC CONDITION.