title: Cholinergic Urticaria with Anaphylaxis: An Underrecognized Clinical Entity.
abstract: BACKGROUND
  Cholinergic urticaria is a form of physical urticaria triggered by high ambient temperature, strenuous physical activity, and strong emotion. These same triggers may cause multisystem reactions that can be life-threatening. A study of patients with cholinergic urticaria with anaphylaxis was undertaken to describe the demographic and clinical features of this form of anaphylaxis.
  
  
  OBJECTIVE
  To describe a cohort of patients with anaphylaxis triggered by high ambient temperature, exertion, and stress.
  
  
  METHODS
  Patients from an academic allergy practice in a university teaching hospital were identified by retrospective chart review.
  
  
  RESULTS
  A total of 19 patients with recurrent episodes of anaphylaxis due to cholinergic triggers were identified. The female:male ratio was 15:4 (79% females). The mean age of onset was 27.5 years. Patients experienced a mean of 9.41 episodes per year. All 19 patients (100%) reported anaphylaxis triggered by high ambient temperature, 89.5% reported anaphylaxis triggered by strenuous exertion, and 78.9% reported anaphylaxis triggered by stress. Cutaneous involvement was present in 94.7%; 78.9% had upper airway obstructive symptoms, 78.9% had lower airway involvement, 57.9% had gastrointestinal involvement, and 78.9% had cardiovascular manifestations. Anaphylaxis severity scores were grade 1 (mild) in 11.1%, grade 2 (moderate) in 44.4%, and grade 3 (severe) in 44.4%. Baseline tryptase levels were normal in all but 1 patient.
  
  
  CONCLUSIONS
  Anaphylaxis due to cholinergic triggers is underreported, with only several case reports in the literature. Reactions are multisystem with cutaneous, upper and lower airway, and cardiovascular involvement in most patients. Manifestations may be life-threatening, and reactions are often severe.
authors.affiliation: Division of Allergy and Clinical Immunology, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Electronic address: vadasp@smh.ca.
authors.forename: Peter
authors.initials: P
authors.lastname: Vadas
authors.affiliation: Division of Allergy and Clinical Immunology, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Angela
authors.initials: A
authors.lastname: Sinilaite
authors.affiliation: Division of Allergy and Clinical Immunology, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Marcus
authors.initials: M
authors.lastname: Chaim
mesh_terms: D000293:Adolescent; D000328:Adult; D000707:Anaphylaxis / Q000175:diagnosis* / Q000453:epidemiology; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000070634:Non-Neuronal Cholinergic System / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D014581:Urticaria / Q000175:diagnosis* / Q000453:epidemiology; D055815:Young Adult
keywords: Anaphylaxis; Cholinergic; Exercise; Exertion; High Ambient Temperature; Idiopathic; Mast cell; Mastocytosis; Urticaria