Atypical Psychosis
The diagnosis of an atypical psychosis is given when a patient displays symptoms that are clearly psychotic; hallucinations, delusions, thought broadcasting, disorganized thinking or other bizarre behaviors, yet those symptoms do not rise to the level required by the DSM-5 to identify a specific psychotic disorder such as schizophrenia.
In a psychological diagnosis "atypical" refers to symptoms that are recognized as part of mental illnesses yet do not rise to the level needed for diagnosis as part of recognized syndromes or do not respond to outside stimuli in the manner most common to a syndrome. To be labeled atypical does not designate that the symptoms being seen are uncommon or rare, mainly that they do not conform to formally recognized conditions or syndromes. Psychotic symptoms are also seen as part of multiple physical, neurological, psychiatric or substance related disorders.