Tumors and other mass lesions of the brain may present with symptoms resembling psychosis or depression or with features of delusions, hallucinations, mania, or catatonia. There is an over-representation of tumors affecting the frontal lobe, temporal lobe, and diencephalon in patients with these manifestations. Neurologic symptoms and signs may be helpful in making an early diagnosis of the tumor. Patients with late-onset psychosis, unusual histories of depression, and those with focal neurologic findings associated with psychotic disorders should undergo computerized tomographic (CT) scanning to exclude a focal brain lesion.