Psychogenic itch.

Psychogenic itch can be defined as "an itch disorder where itch is at the center of the symptomatology and where psychological factors play an evident role in the triggering, intensity, aggravation, or persistence of the pruritus." The disorder is poorly known by both psychiatrists and dermatologists and this review summarizes data on psychogenic itch. Because differential diagnosis is difficult, the frequency is poorly known. The burden is huge for people suffering from this disorder but a management associating psychological and pharmacological approach could be very helpful. Classification, psychopathology, and physiopathology are still debating. New data from brain imaging could be very helpful. Psychological factors are known to modulate itch in all patients, but there is a specific diagnosis of psychogenic itch that must be proposed cautiously. Neurophysiological and psychological theories are not mutually exclusive and can be used to better understand this disorder. Itch can be mentally induced. Opioids and other neurotransmitters, such as acetylcholine and dopamine, are probably involved in this phenomenon.