title: High prevalence of anaphylaxis in patients with systemic mastocytosis - a single-centre experience.
abstract: BACKGROUND
  Systemic mastocytosis (SM) is a clonal mast cells disorder characterized by the proliferation, accumulation and activation of mast cells in extracutaneous tissues. The clinical picture is heterogeneous and may range from asymptomatic to potentially fatal anaphylactic reactions due to excessive mast cell mediator release.
  
  
  OBJECTIVE
  The aim of this study was to investigate the prevalence and trigger factors of anaphylactic reactions among adult SM patients. We also explored the clinical spectrum of mast cell mediator-related symptoms in patients with SM.
  
  
  METHODS
  This descriptive study was performed among 84 consecutive adult (≥ 18 years) patients those were diagnosed with SM according to WHO criteria. Sixty-six of the patients also underwent a comprehensive allergy work-up.
  
  
  RESULTS
  Sixty of 84 patients with SM (71%) had bone marrow mast cell aggregates and fulfilled the major criteria for SM and 76 patients (91%) had indolent disease. Simultaneous occurrence of cutaneous mastocytosis was observed in 59 patients (70%). Thirty-six patients (43%) had had at least one episode of an anaphylactic reaction. The clinical courses of the reactions were usually severe and patients often presented with syncope attacks (72%). Most patients reacted after hymenoptera venom stings (19/36; 53%). In 39% (14/36), a clear aetiology could not be determined. While males and females were equally frequent among the patients with SM, anaphylaxis patients showed a male predominance (61%). Anaphylactic reactions occurred more frequently in patients without cutaneous engagement. The rate of allergy sensitization was significantly higher in SM patients with anaphylaxis as compared with non-anaphylaxis SM patients, 70% vs. 23%, respectively (P = 0.0002).
  
  
  CONCLUSIONS
  Anaphylaxis is more prevalent in patients with SM, predominantly in patients with atopic SM. Hymenoptera venom-induced and idiopathic anaphylaxis were the most frequent elicitors. Our findings implicate that all mastocytosis patients with anaphylaxis should undergo detailed allergological assessment before considering treatment and preventive measures.
authors.affiliation: Department of Respiratory Medicine and Allergy, Karolinska University Hospital, Huddinge, Stockholm, Sweden; Department of Medicine, Clinical Immunology and Allergy Research Unit, Karolinska University Hospital, Karolinska Institutet, Solna, Stockholm, Sweden; Mastocytosis Centre Karolinska, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden; Centre for Allergy Research (CfA), Karolinska Institutet, Stockholm, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Gülen
authors.forename: H
authors.initials: H
authors.lastname: Hägglund
authors.forename: B
authors.initials: B
authors.lastname: Dahlén
authors.forename: G
authors.initials: G
authors.lastname: Nilsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000485:Allergens / Q000276:immunology; D000707:Anaphylaxis / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D015897:Comorbidity; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D008297:Male; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism; D034721:Mastocytosis, Systemic / Q000150:complications*; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012882:Skin Tests; D055815:Young Adult
chemical_list: D000485:Allergens; D007073:Immunoglobulin E
keywords: IgE sensitization; anaphylaxis; atopic disease; hymenoptera venom; mastocytosis; prevalence; tryptase