Organic and non-organic illnesses may present with uncommon symptoms. In some cases, the presenting atypical symptoms make a prompt and accurate diagnosis difficult. Accordingly, unequivocal psychotic and affective symptoms also require adequate evaluation before determining the diagnosis and management. Here we present a case whose presenting symptoms strongly suggested an organic etiology, namely autoimmune psychosis, but failed to be diagnosed as such through laboratory tests and didn't respond to appropriate treatment. Re-evaluation of the case revealed significant past psychiatric history, suggesting functional psychosis but the patient did not respond to anti-psychotic medications either. This case therefore highlights the importance of complete unbiased work-up for all psychoses.