title: Silent somatotroph tumour revisited from a study of 80 patients with and without acromegaly and a review of the literature.
abstract: BACKGROUND
  Silent somatotroph tumours are growth hormone (GH) immunoreactive (IR) pituitary tumours without clinical and biological signs of acromegaly. Their better characterisation is required to improve the diagnosis.
  
  
  METHODS
  Twenty-one silent somatotroph tumours were compared to 59 somatotroph tumours with acromegaly. Tumours in each group were classified into GH and plurihormonal (GH/prolactin (PRL)/±thyroid-stimulating hormone (TSH)) and into densely granulated (DG) and sparsely granulated (SG) types. The two groups were then compared with regards to proliferation (Ki-67, p53 indexes and mitotic count), differentiation (expression of somatostatin receptors SSTR2A-SSTR5and transcription factor Pit-1) and secretory activity (% of GH- and PRL-IR cells).
  
  
  RESULTS
  The silent somatotroph tumours represented 2% of all tested pituitary tumours combined. They were more frequent in women than in men (P = 0.002), more frequently plurihormonal and SG (P < 0.01), with a lower percentage of GH-IR cells (P < 0.0001) compared to those with acromegaly. They all expressed SSTR2A, SSTR5and Pit-1. The plurihormonal (GH/PRL/±TSH) tumours were mostly observed in women (sex ratio: 3/1) and in patients who were generally younger than those with acromegaly (P < 0.001). They were larger (P < 0.001) with a higher Ki-67 index (P = 0.007).
  
  
  CONCLUSIONS
  The silent somatotroph tumours are not uncommon. Their pathological diagnosis requires the immunodetection of GH and Pit-1. They are more frequently plurihormonal and more proliferative than those with acromegaly. A low secretory activity of these tumours might explain the normal plasma values for GH and insulin-like growth factor 1 (IGF1) and the absence of clinical signs of acromegaly.
authors.affiliation: Department of HistologyUniversity of Medicine and Pharmacy, Tirgu Mures, Romania.
authors.forename: Laura
authors.initials: L
authors.lastname: Chinezu
authors.affiliation: Faculté de Médecine Lyon-Est Université Lyon 1, Lyon, France.|Centre de Pathologie et de Biologie Est.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vasiljevic
authors.affiliation: Faculté de Médecine Lyon-Est Université Lyon 1, Lyon, France.|Centre de Pathologie et de Biologie Est.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Trouillas
authors.affiliation: Faculté de Médecine Lyon-Est Université Lyon 1, Lyon, France.|Fédération d'EndocrinologieGroupement Hospitalier Est, Hospices Civils de Lyon, Bron, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Lapoirie
authors.affiliation: Faculté de Médecine Lyon-Est Université Lyon 1, Lyon, France.|INSERM U1052; CNRS UMR5286; Cancer Research Center of LyonLyon, France.|Service de NeurochirurgieGroupement Hospitalier Est, Hospices Civils de Lyon, Bron, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Jouanneau
authors.affiliation: Faculté de Médecine Lyon-Est Université Lyon 1, Lyon, France gerald.raverot@chu-lyon.fr.|Fédération d'EndocrinologieGroupement Hospitalier Est, Hospices Civils de Lyon, Bron, France.|INSERM U1052; CNRS UMR5286; Cancer Research Center of LyonLyon, France.
authors.forename: Gérald
authors.initials: G
authors.lastname: Raverot
mesh_terms: D000172:Acromegaly / Q000378:metabolism*; D000328:Adult; D005260:Female; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007633:Keratins / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000378:metabolism*; D017481:Receptors, Somatostatin / Q000378:metabolism; D013002:Somatomedins / Q000378:metabolism; D052683:Somatotrophs / Q000378:metabolism; D013972:Thyrotropin; D050817:Transcription Factor Pit-1 / Q000378:metabolism
chemical_list: D017481:Receptors, Somatostatin; D013002:Somatomedins; D050817:Transcription Factor Pit-1; D007334:Insulin-Like Growth Factor I; D007633:Keratins; C094573:somatostatin receptor 5; D013972:Thyrotropin; D013006:Growth Hormone; C093733:somatostatin receptor 2