title: Catecholamine-Synthesizing Enzymes Are Expressed in Parasympathetic Head and Neck Paraganglioma Tissue.
abstract: OBJECTIVE
  Increased dopamine production may be a feature of head and neck paraganglioma (HNPGL). 18F-fluorodihydroxyphenylalanine positron emission tomography scintigraphy has a high sensitivity for detecting HNPGLs. These observations strongly suggest that HNPGLs have the capacity for L-3,4-dihydroxyphenylalanine uptake and conversion towards dopamine. Therefore, our aim was to demonstrate the presence of catecholamine-synthesizing enzymes, i.e. tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC) and dopamine β-hydroxylase (DBH) in HNPGL tissue.
  
  
  METHODS
  A single-center study was performed among patients who underwent surgery for HNPGL at a single university referral center between 1994 and 2012. HNPGL tissue was immunohistochemically stained for TH, AADC and DBH. Data on paraganglioma-associated germline mutations, preoperative biochemical phenotype and imaging studies were retrieved. Catecholamine excess was defined as preoperative plasma and/or urinary levels of metanephrine, normetanephrine or 3-methoxytyramine above the upper reference limit.
  
  
  RESULTS
  Nineteen HNPGLs from 18 patients were evaluated. All tumor tissues (100%) stained positive for AADC, 6 (32%) for TH and 2 (11%) for DBH. Of 3 HNPGLs staining positive for DBH, 2 were also positive for AADC and TH. Catecholamine excess was only present in 1 patient (5%). The HNPGLs of this single patient only showed positive staining for AADC.
  
  
  CONCLUSIONS
  Catecholamine-synthesizing enzymes, in particular AADC, are expressed in the majority of HNPGL tissues.
authors: Department of Endocrinology and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors: Thamara E
authors: TE
authors: Osinga
authors: Esther
authors: E
authors: Korpershoek
authors: Ronald R
authors: RR
authors: de Krijger
authors: Michiel N
authors: MN
authors: Kerstens
authors: Robin P F
authors: RP
authors: Dullaart
authors: Ido P
authors: IP
authors: Kema
authors: Bernard F A M
authors: BF
authors: van der Laan
authors: Anouk N A
authors: AN
authors: van der Horst-Schrivers
authors: Thera P
authors: TP
authors: Links
mesh_terms: D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000378:metabolism*; D004298:Dopamine / Q000031:analogs & derivatives / Q000097:blood / Q000652:urine; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism*; D005260:Female; D006258:Head and Neck Neoplasms / Q000097:blood / Q000201:enzymology* / Q000601:surgery / Q000652:urine; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008676:Metanephrine / Q000097:blood / Q000652:urine; D008875:Middle Aged; D009647:Normetanephrine / Q000097:blood / Q000652:urine; D010673:Pheochromocytoma / Q000097:blood / Q000201:enzymology* / Q000601:surgery / Q000652:urine; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D009647:Normetanephrine; D008676:Metanephrine; D014446:Tyrosine 3-Monooxygenase; D004299:Dopamine beta-Hydroxylase; D001142:Aromatic-L-Amino-Acid Decarboxylases; C001746:3-methoxytyramine; D004298:Dopamine