Psychogenic disease

A psychogenic disease is any physical disease where the underlying cause is the patient's mental state. They can arise from mental stress, emotional stress, or a psychiatric condition. 
Such a disease becomes a part of a differential diagnosis when all possible physical conditions that can cause the patient's symptoms have been ruled out, even if they patient's current mental state appears normal and the patient claims no history of stress. 
The condition can present with many symptoms, but the most common are seizures, excessive fluid intake in the absence of thirst, tremors and pain.
Unlike a psychosomatic illness, psychogenic diseases do not present with any underlying but mild physical symptoms which the patients often exaggerate, and patients generally show no anxiety about their condition. 
Psychogenic disease at Wikipedia