title: ALDH1 is an immunohistochemical diagnostic marker for solitary fibrous tumours and haemangiopericytomas of the meninges emerging from gene profiling study.
abstract: BACKGROUND
  Solitary Fibrous Tumours (SFT) and haemangiopericytomas (HPC) are rare meningeal tumours that have to be distinguished from meningiomas and more rarely from synovial sarcomas. We recently found that ALDH1A1 was overexpressed in SFT and HPC as compared to soft tissue sarcomas. Using whole-genome DNA microarrays, we defined the gene expression profiles of 16 SFT/HPC (9 HPC and 7 SFT). Expression profiles were compared to publicly available expression profiles of additional SFT or HPC, meningiomas and synovial sarcomas. We also performed an immunohistochemical (IHC) study with anti-ALDH1 and anti-CD34 antibodies on Tissue Micro-Arrays including 38 SFT (25 meningeal and 13 extrameningeal), 55 meningeal haemangiopericytomas (24 grade II, 31 grade III), 163 meningiomas (86 grade I, 62 grade II, 15 grade III) and 98 genetically confirmed synovial sarcomas.
  
  
  RESULTS
  ALDH1A1 gene was overexpressed in SFT/HPC, as compared to meningiomas and synovial sarcomas. These findings were confirmed at the protein level. 84% of the SFT and 85.4% of the HPC were positive with anti-ALDH1 antibody, while only 7.1% of synovial sarcomas and 1.2% of meningiomas showed consistent expression. Positivity was usually more diffuse in SFT/HPC compared to other tumours with more than 50% of tumour cells immunostained in 32% of SFT and 50.8% of HPC. ALDH1 was a sensitive and specific marker for the diagnosis of SFT (SE = 84%, SP = 98.8%) and HPC (SE = 84.5%, SP = 98.7%) of the meninges. In association with CD34, ALDH1 expression had a specificity and positive predictive value of 100%.
  
  
  CONCLUSIONS
  We show that ALDH1, a stem cell marker, is an accurate diagnostic marker for SFT and HPC, which improves the diagnostic value of CD34. ALDH1 could also be a new therapeutic target for these tumours which are not sensitive to conventional chemotherapy.
authors.affiliation: Department of Neuropathology and APHM Tumor Bank, LaTimone Hospital, Marseille, France. corinne.bouvier@univ-amu.fr.
authors.forename: Corinne
authors.initials: C
authors.lastname: Bouvier
authors.forename: François
authors.initials: F
authors.lastname: Bertucci
authors.forename: Philippe
authors.initials: P
authors.lastname: Métellus
authors.forename: Pascal
authors.initials: P
authors.lastname: Finetti
authors.forename: André
authors.initials: A
authors.lastname: Maues de Paula
authors.forename: Fabien
authors.initials: F
authors.lastname: Forest
authors.forename: Karima
authors.initials: K
authors.lastname: Mokhtari
authors.forename: Catherine
authors.initials: C
authors.lastname: Miquel
authors.forename: Daniel
authors.initials: D
authors.lastname: Birnbaum
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vasiljevic
authors.forename: Anne
authors.initials: A
authors.lastname: Jouvet
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Coindre
authors.forename: Anderson
authors.initials: A
authors.lastname: Loundou
authors.forename: Dominique
authors.initials: D
authors.lastname: Figarella-Branger
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D000080924:Aldehyde Dehydrogenase 1 Family; D018952:Antigens, CD34 / Q000235:genetics / Q000378:metabolism; D014408:Biomarkers, Tumor; D020869:Gene Expression Profiling; D006393:Hemangiopericytoma / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008577:Meningeal Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008579:Meningioma / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D046228:Microarray Analysis; D060787:Neoplasm Grading; D012333:RNA, Messenger / Q000378:metabolism; D050697:Retinal Dehydrogenase; D013584:Sarcoma, Synovial / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity; D054364:Solitary Fibrous Tumors / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D000080924:Aldehyde Dehydrogenase 1 Family; D000444:Aldehyde Dehydrogenase; C510223:ALDH1A1 protein, human; D050697:Retinal Dehydrogenase