title: Parathyroid carcinoma: increasing incidence and  changing presentation.
abstract: BACKGROUND
  Parathyroid carcinoma has been regarded as an exceedingly rare disease worldwide, responsible for less than 1% of cases of primary hyperparathyroidism. However, there have been anecdotal reports recently of an increasing number of patients presenting with parathyroid carcinoma. The aim of this study was to examine the changing incidence and presentation of parathyroid cancer within a single centre.
  
  
  METHODS
  This is a retrospective case series. Data were obtained from the University of Sydney Endocrine Surgical Unit database, as well as a review of hospital records. All pathology was independently reviewed.
  
  
  RESULTS
  Over the 52-year period of the study from 1958 to 2010, there were 21 cases of confirmed parathyroid cancer. Only three cases were reported in the first 30 years of the study with the majority of cases (n = 11) presenting in the last 5 years. Despite the exponential increase in presentations, no significant differences in demographics or mode of presentation were found.
  
  
  CONCLUSIONS
  Possible reasons for the dramatic increase in parathyroid cancer include increased screening, an increase in referrals for parathyroid surgery overall associated with the availability of minimally invasive techniques, changes in diagnostic techniques with immunohistochemistry for parafibromin and protein gene product 9.5 (PGP9.5) or possibly a true increase in the incidence of the disease.
authors.affiliation: University of Sydney Endocrine Surgical Unit, Royal North Shore Hospital, New South Wales, Australia.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Brown
authors.forename: Christine
authors.initials: C
authors.lastname: O'Neill
authors.forename: James
authors.initials: J
authors.lastname: Suliburk
authors.forename: Stan
authors.initials: S
authors.lastname: Sidhu
authors.forename: Mark
authors.initials: M
authors.lastname: Sywak
authors.forename: Anthony
authors.initials: A
authors.lastname: Gill
authors.forename: Bruce
authors.initials: B
authors.lastname: Robinson
authors.forename: Leigh
authors.initials: L
authors.lastname: Delbridge
mesh_terms: D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010282:Parathyroid Neoplasms / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology*; D055815:Young Adult