General Description
A disorder characterized by the development either of a single delusion or of a set of related delusions that are usually persistent and sometimes lifelong. The content of the delusion or delusions is very variable.
Clear and persistent auditory hallucinations (voices), schizophrenic symptoms such as delusions of control and marked blunting of affect, and definite evidence of brain disease are all incompatible with this diagnosis. However, the presence of occasional or transitory auditory hallucinations, particularly in elderly patients, does not rule out this diagnosis, provided that they are not typically schizophrenic and form only a small part of the overall clinical picture.

Examples
A: One or more nonbizarre (ie, involving situations that could occur in real life) delusion(s) is present for at least 1 month.
B: Criterion A for schizophrenia has never been met. (Auditory and visual hallucinations may be present but are not prominent, while tactile and olfactory hallucinations often are present if related to the delusional theme.)
C: Apart from the impact of the delusion, functioning is not impaired markedly, and behavior is not obviously bizarre.
D: Mood episodes that may have occurred are relatively brief relative to the delusional periods.
E: The disturbance is not due to the direct effects of a substance or a general medical condition.
Subtypes are defined, including erotomanic, grandiose, jealous, persecutory, somatic, mixed, and unspecified.