title: Glut-1 intensity and pattern of expression in thymic epithelial tumors are predictive of WHO subtypes.
abstract: OBJECTIVE
  Glucose-transporter-1 (Glut-1) may be a useful marker for differentiating B3 thymomas and thymic carcinomas. Since the literature is limited, we undertook a study to evaluate its diagnostic value in a series of thymic epithelial tumors.
  
  
  METHODS
  Glut-1 expression was studied by the group of pathologists linked to the French national oncological network RYTHMIC. Immunostaining was performed on a whole section of one paraffin block in a series of 92 successive surgical specimens. Patterns (focal, zonal, diffuse) and intensity of Glut-1 expression were assessed and compared with WHO histological subtypes.
  
  
  RESULTS
  Expression was mainly restricted to epithelial cells. Immature T-lymphocytes were negative. A diffuse, moderate or strong staining was observed in most thymic carcinomas (15/16). In B3 thymomas (10/11) and in B3 thymomas borderline to thymic carcinomas (5/6), a moderate to strong zonal staining was observed at distance from vessels and fibrous septa. This pattern sometimes created the aspect of an anastomosing network in large cellular lobules. In B1 thymomas, immunostaining highlighted foci of medullary differentiation (7/8). B2 thymomas (n=25) were heterogeneous, with a spectrum of patterns ranging between those of B1 and B3 thymomas. Type A thymomas (n=5) mostly presented a weak positivity but one aggressive case showed zonal moderate/strong positivity. Most AB thymomas (15/17) showed weak to moderate immunostaining in spindle cell areas. In micronodular thymomas (n=3), epithelial cells and B-lymphocytes were weakly positive while follicular dendritic cells were strongly highlighted. One metaplastic thymoma displayed diffuse and moderate positivity.
  
  
  CONCLUSIONS
  Glut-1 expression globally depended on histological subtypes and the staining patterns (diffuse or zonal) were different between thymic carcinomas and type B3 thymomas. A comparative study of Glut-1 expression in atypical versus conventional type A thymomas appears warranted. Otherwise, restriction to epithelial cells makes likely a correlation with clinical assessment of glucose uptake in lymphocyte-poor tumors.
authors.affiliation: Centre Chirurgical Marie Lannelongue, Département de Pathologie, Le Plessis Robinson, France. Electronic address: v.thomasdemontprevil@ccml.fr.
authors.forename: Vincent
authors.initials: V
authors.lastname: Thomas de Montpréville
authors.affiliation: Centre Chirurgical Marie Lannelongue, Département de Pathologie, Le Plessis Robinson, France.
authors.forename: Pauline
authors.initials: P
authors.lastname: Quilhot
authors.affiliation: Hôpital Louis-Pradel, Département de Pathologie, Lyon, France.
authors.forename: Lara
authors.initials: L
authors.lastname: Chalabreysse
authors.affiliation: Chu de Tours, Département de Pathologie, Tours, France.
authors.forename: Anne
authors.initials: A
authors.lastname: De Muret
authors.affiliation: Hôpital Pasteur, CHU de Nice, Laboratoire de Pathologie Clinique et Expérimentale, Nice, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Hofman
authors.affiliation: CHU de Grenoble, Département d'Anatomie et de Cytologie Pathologiques, Grenoble, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lantuéjoul
authors.affiliation: CHU de Bordeaux, Dr Parrens: EA 2406 Département de Pathologie, Bordeaux, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Parrens
authors.affiliation: Hôpital Nord, APHM, Laboratoire d'Anatomie Pathologique, Marseille, France.
authors.forename: Marie-José
authors.initials: MJ
authors.lastname: Payan
authors.affiliation: CHU Rangueil, Service d'Anatomie Pathologique, Toulouse, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Rouquette
authors.affiliation: Hôpital Nord, APHM, Laboratoire d'Anatomie Pathologique, Marseille, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Secq
authors.affiliation: Hôpital Louis-Pradel, Hospices Civils de Lyon, Département des Maladies Respiratoires, Lyon, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Girard
authors.affiliation: Institut Gustave Roussy, Département de Médecine, Villejuif, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Besse
authors.affiliation: Centre Universitaire Médical de Mannheim, Université de Heidelberg, Institut de Pathologie, Mannheim, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Marx
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Service de Pathologie, AP-HP Hôpital Necker Enfants Malades, Paris, France.
authors.forename: Thierry Jo
authors.initials: TJ
authors.lastname: Molina
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D051272:Glucose Transporter Type 1 / Q000032:analysis / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D009375:Neoplasms, Glandular and Epithelial / Q000473:pathology*; D013953:Thymus Neoplasms / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D051272:Glucose Transporter Type 1
keywords: Glut-1; Immuno-histochemistry; Thymic carcinoma; Thymoma