Snapshot A 16-year-old boy presents to the clinic for an itchy rash on his hands. He reports he is concerned because of an ongoing pandemic, and he cannot help but wash his hands every hour while awake, even if he did not leave the house or touch anything dirty. He reports being very preoccupied with thoughts of having “dirty” hands filled with microorganisms and feels partial relief when he washes his hands thoroughly with soap and water. On exam, he has pink scaly plaques on his hands and tiny vesicles along the lateral fingers, consistent with hand dermatitis. He is prescribed a strong topical steroid cream and referred to psychiatry for management of suspected obsessive-compulsive disorder. Introduction Overview obsessive-compulsive disorder (OCD) is characterized by obsessive intrusive thoughts, sensations, or feelings that may be relieved by repetitive compulsive mental or physical actions treatment is usually cognitive behavioral therapy or medications Epidemiology incidence common, with a lifetime prevalence of 1.7-4% demographics males are more likely to have onset in adolescence and to have a comorbid tic disorder risk factors family history Pathogenesis mechanism exact pathogenesis is unclear but research suggests that there are abnormalities in serotonin neurotransmission twin studies also show a genetic influence, although a genetic mutation has not been identified ego dystonic behavior inconsistent with one's own beliefs and attitudes separates OCD from obsessive-compulsive personality disorder Associated conditions patients often have other psychiatric comorbidities, including mood and anxiety disorders associated with Tourette disorder, increased activity of the caudate nucleus Prognosis symptoms wax and wane, even with treatment Presentation Symptoms obsessions and compulsions often occupy hours a day and interfere with daily life recurrent and persistent intrusive thoughts (obsessions) common obsessions include fear of contamination, need for symmetry, unwanted sexual thoughts, and doubts causes anxiety and distress repetitive behaviors (compulsions) hand washing putting items in order checking and rechecking tasks Physical exam hand dermatitis related to excessive hand washing patchy hair loss related to compulsive hair pulling or trichotillomania excoriations or prurigo nodules related to compulsive skin picking Studies Yale-Brown Obsessive Compulsive scale to evaluate range and severity of symptoms to monitor treatment response Differential Intrinsic atopic dermatitis key distinguishing factors treatment with topical steroids can help resolve rash treatment with cognitive behavioral therapy and control of compulsions may not result in resolution of rash Body dysmorphic disorder key distinguishing factors preoccupation with a perceived defect in one’s appearance, causing significant distress, and dysfunction treatment with cognitive behavioral therapy Treatment Lifestyle cognitive behavioral therapy (CBT) indications all patients some patients may not need pharmacologic treatment with successful behavioral therapy Medical serotonin selective reuptake inhibitors (SSRIs) indications first-line often in addition to CBT tricyclic antidepressant indication second-line Complications Continued psychologic distress and functional impairment