Background: Obsessive-compulsive disorder (OCD) is considered one of the most debilitating of the psychiatric illnesses, yet much remains unclear regarding causes and cures. A diagnostic subgroup with acute onset of obsessive-compulsive symptoms (and sometimes tics or anorexia nervosa) possibly due to an autoimmune response, has been entitled Pediatric Acute onset Neuropsychiatric Syndrome (PANS). PANS is sometimes treated with immunomodulatory therapy or antibiotics, with a variable outcome. A diagnosis of PANS is supported by elevated levels of auto-antibodies and antibody-enzyme activity measured with the Cunningham panel, but the relationship between these biomarkers and the patients' symptoms remains unclear. A clinician rated symptom scale for PANS (the PANS scale) has been developed, but needs to be further evaluated regarding sensitivity and specificity.