Since 3000 B.C. Man has been trying to classify mental disorders. However, there is still much to be done and the differential diagnosis of psychotic disorders remains one of the greatest challenges in modern psychiatry.

We aim to improve the differential diagnosis of psychotic disorders, namely by rethinking schizophrenia spectrum disorders as syndromes whose hallmark are not delusions or hallucinations.

We present the clinical report of a 57 year old woman admitted in our unit who was diagnosed with maniac type schizoaffective disorder. Her previous medical records documented different diagnosis, namely schizophrenia and bipolar disorder. Hence, we attempt to understand the evolution of classification systems, how clinical practice deals with these systems and how the future DSM-V and ICD-11 may correct existing flaws.

We demonstrate that the definition of psychotic symptom should be restricted to delusions and/or hallucinations, thus there is a need to rethink the core symptoms of schizophrenia spectrum disorders. Furthermore, the assessment of a patient should always take into account the longitudinal development of the disease, retrieving one of Kraeplin's concepts. We found conflicts between the existing classification systems and extraordinary shortcomings, such as a 50% chance of failure of DSMIV temporal diagnostic reliability.

Current clinical practice continues to give much emphasis to research on delusions and hallucinations - contradicting Bleuler's concepts - and neglecting other dimensions - cognitive dysfunction, disorganization and negative, affective and motor symptoms. The integration of these symptoms in stable diagnoses remains a challenge.