title: Systemic mastocytosis: A cohort study on clinical characteristics of 136 patients in a large tertiary centre.
abstract: BACKGROUND
  Systemic mastocytosis (SM) is a rare heterogeneous disease which is characterized by the aberrant proliferation of mast cells. It can be divided into various subtypes with different phenotypes and prognoses. Here, we report on the clinical characteristics of 136 SM patients.
  
  
  METHODS
  A retrospective cohort study was conducted from January 2009 to September 2014 in a large tertiary centre in The Netherlands. We included all patients who fulfilled WHO criteria for SM. Data were collected from electronic patient files.
  
  
  RESULTS
  A total of 124 patients had indolent SM (ISM) (91.2%), 7 had aggressive SM (ASM) (5.1%) and 5 had SM with associated hematological non-mast cell lineage disease (SM-AHNMD) (3.7%). There was no progression from ISM to advanced SM subtypes, but 1 patient with ASM developed chronic myelocytic leukemia 2years after diagnosis. The average time to diagnosis for the whole population was 8.1years (range, 0-49years). The most frequent triggers for work-up-skin involvement, anaphylaxis and osteoporosis-were characterized by an interval to diagnosis of 10.9, 2.9 and 7.5years, respectively. A total of 32 patients (23.5%) had a serum tryptase levels below the cutoff value of 20ng/mL at the time of diagnosis, but these patients did not have significant differences in clinical phenotype.
  
  
  CONCLUSIONS
  SM comprises a wide spectrum of signs and symptoms and its often atypical presentation can delay the establishment of the diagnosis substantially. Skin involvement, anaphylaxis and unexplained osteoporosis should trigger analysis for mastocytosis. A normal serum tryptase does not exclude the diagnosis of SM.
authors.affiliation: Section of Clinical Immunology, Internal Medicine, Erasmus MC University Medical Centre, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands. Electronic address: m.hermans@erasmusmc.nl.
authors.forename: Maud A W
authors.initials: MAW
authors.lastname: Hermans
authors.affiliation: Section of Clinical Immunology, Internal Medicine, Erasmus MC University Medical Centre, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: Mark J A
authors.initials: MJA
authors.lastname: Rietveld
authors.affiliation: Section of Clinical Immunology, Internal Medicine, Erasmus MC University Medical Centre, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: Jan A M
authors.initials: JAM
authors.lastname: van Laar
authors.affiliation: Section of Clinical Immunology, Internal Medicine, Erasmus MC University Medical Centre, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: Virgil A S H
authors.initials: VASH
authors.lastname: Dalm
authors.affiliation: Section of Paediatric Dermatology, Dermatology, Erasmus MC University Medical Centre, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: Maurice
authors.initials: M
authors.lastname: Verburg
authors.affiliation: Section of Paediatric Dermatology, Dermatology, Erasmus MC University Medical Centre, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: Suzanne G M A
authors.initials: SGMA
authors.lastname: Pasmans
authors.affiliation: Section of Allergology, Internal Medicine, Erasmus MC University Medical, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: Roy
authors.initials: R
authors.lastname: Gerth van Wijk
authors.affiliation: Section of Clinical Immunology, Internal Medicine, Erasmus MC University Medical Centre, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: P Martin
authors.initials: PM
authors.lastname: van Hagen
authors.affiliation: Section of Clinical Immunology, Internal Medicine, Erasmus MC University Medical Centre, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: Paul L A
authors.initials: PLA
authors.lastname: van Daele
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000707:Anaphylaxis / Q000453:epidemiology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008407:Mast Cells / Q000166:cytology*; D034721:Mastocytosis, Systemic / Q000150:complications* / Q000175:diagnosis*; D008875:Middle Aged; D009426:Netherlands; D010024:Osteoporosis / Q000453:epidemiology*; D012189:Retrospective Studies; D062606:Tertiary Care Centers; D053802:Tryptases / Q000097:blood*; D055815:Young Adult
chemical_list: D053802:Tryptases
keywords: Anaphylaxis; Osteoporosis; Systemic mastocytosis; Tryptase