Delusional parasitosis: a dermatologic, psychiatric, and pharmacologic approach.

Delusional parasitosis is a syndrome in which the patient has the false belief that he is infested by parasites. Although this is a psychiatric disorder, patients usually seek care from dermatologists. DP has various causes. It may occur as the sole psychologic disturbance, or it may be associated with an underlying psychiatric disorder or physical illness. A dermatology-psychiatry liaison is advocated for establishing a viable differential diagnosis and selecting appropriate therapy. The antipsychotic agent pimozide is currently the most effective treatment when DP occurs as an encapsulated delusion. Pimozide therapy requires careful monitoring because this drug has several potentially serious adverse effects, and relapse often occurs on discontinuation of the drug.