title: Clonal mast cell disorders in patients with severe Hymenoptera venom allergy and normal serum tryptase levels.
abstract: BACKGROUND
  Systemic mastocytosis is a clonal mast cell (MC) disease that can lead to potentially fatal anaphylactic reactions caused by excessive MC mediator release. The prevalence of mastocytosis in patients with Hymenoptera venom allergy is high, and thus the disease should be suspected in patients with severe reactions caused by Hymenoptera stings and increased serum basal tryptase (SBT) levels.
  
  
  OBJECTIVE
  We sought to evaluate the presence of clonal MC disorders in patients seen at our mastocytosis center with Hymenoptera sting-induced anaphylaxis, documented hypotension, absence of urticaria pigmentosa, and normal SBT levels.
  
  
  METHODS
  Twenty-two patients with Hymenoptera sting-induced anaphylaxis, without skin lesions, and with tryptase levels of less than 11.4 ng/mL underwent bone marrow evaluation. Bone mineral density was assessed in those patients with ascertained mastocytosis.
  
  
  RESULTS
  In 16 of 22 patients, a diagnosis of indolent mastocytosis could be established, and 1 patient had a monoclonal MC activation syndrome. Patients with mastocytosis had higher SBT levels (P = .03) but only rarely had angioedema/urticaria associated with hypotension (P = .004).
  
  
  CONCLUSIONS
  The absence of urticaria or angioedema in severe reactions to Hymenoptera stings with hypotension might represent the most relevant factor in identifying patients with mastocytosis, regardless of their serum tryptase levels.
authors.affiliation: Department of Medicine, Section of Hematology, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy; Multidisciplinary Mastocytosis Outpatient Clinic, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Zanotti
authors.affiliation: Allergy Unit, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Lombardo
authors.affiliation: Allergy and Respiratory Diseases, IRCCS San Martino-IST, University of Genoa, Genoa, Italy. Electronic address: passalacqua@unige.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Passalacqua
authors.affiliation: Department of Medicine, Section of Rheumatology, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Cristian
authors.initials: C
authors.lastname: Caimmi
authors.affiliation: Department of Medicine, Section of Hematology, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy; Multidisciplinary Mastocytosis Outpatient Clinic, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Bonifacio
authors.affiliation: Clinical Chemistry and Haematology, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: De Matteis
authors.affiliation: Department of Medicine, Section of Hematology, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Omar
authors.initials: O
authors.lastname: Perbellini
authors.affiliation: Multidisciplinary Mastocytosis Outpatient Clinic, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy; Department of Medicine, Section of Rheumatology, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Rossini
authors.affiliation: Multidisciplinary Mastocytosis Outpatient Clinic, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy; Department of Medicine, Section of Dermatology, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: Schena
authors.affiliation: Dermatology Unit, ULSS 13, Mirano, Venice, Italy.
authors.forename: Moira
authors.initials: M
authors.lastname: Busa
authors.affiliation: Pulmonology Unit, Azienda Ospedaliera di Desenzano, Brescia, Italy.
authors.forename: Maria Cinzia
authors.initials: MC
authors.lastname: Marcotulli
authors.affiliation: Allergy Unit, Department of Internal Medicine, Ospedali Riuniti di Ancona, Ancona, Italy.
authors.forename: Maria Beatrice
authors.initials: MB
authors.lastname: Bilò
authors.affiliation: Allergy Service, ULSS 10, Jesolo, Venice, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Franchini
authors.affiliation: Allergy Service, ULSS 21 Legnago, Verona, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Marchi
authors.affiliation: Department of Medicine, Allergy Service, ULSS 2 di Feltre, Belluno, Italy.
authors.forename: Livio
authors.initials: L
authors.lastname: Simioni
authors.affiliation: Multidisciplinary Mastocytosis Outpatient Clinic, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy; Allergy Unit, Azienda Ospedaliera Universitaria Integrata of Verona, Verona, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Bonadonna
mesh_terms: D000328:Adult; D000368:Aged; D000485:Allergens / Q000276:immunology; D000707:Anaphylaxis / Q000209:etiology / Q000276:immunology*; D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology*; D005260:Female; D006801:Humans; D006927:Hymenoptera / Q000276:immunology; D006967:Hypersensitivity / Q000150:complications / Q000276:immunology*; D007299:Insect Bites and Stings / Q000150:complications / Q000276:immunology*; D008297:Male; D008407:Mast Cells / Q000276:immunology*; D008415:Mastocytosis / Q000209:etiology / Q000276:immunology*; D008875:Middle Aged; D053802:Tryptases / Q000097:blood; D014688:Venoms / Q000276:immunology
chemical_list: D000485:Allergens; D014688:Venoms; D053802:Tryptases
keywords: Hymenoptera venom allergy; Systemic mastocytosis; anaphylaxis; tryptase