Delusional disorder is a psychiatric condition in which the patients present with delusions, but with no accompanying prominent hallucinations, thought disorder, mood disorder, or significant flattening of affect.Delusions are a specific symptom of psychosis. Delusions can be bizarre or non-bizarre in content.n delusional disorder, mood symptoms tend to be brief or absent, and unlike schizophrenia, delusions are non-bizarre and hallucinations are minimal or absent.