Delusion of oral parasitosis in a patient with major depressive disorder.

Delusion of parasitosis is a rare condition in which the patient has a strong conviction that he or she is infested by small organisms. The condition may exist as an isolated phenomenon, or may occur in association with other psychiatric syndromes. We report a single case of a rare form of this phenomenon. A middle-aged woman who met forth edition of diagnostic and statistical manual of mental disorders criteria for major depressive disorder with psychotic features is described. She had delusions of oral parasitosis. She felt lizards and small organisms in her mouth. To the best of our knowledge, there has been only one previous report of delusions of oral parasitosis to date. We discuss the interesting aspects of this case.