title: SDHD immunohistochemistry: a new tool to validate SDHx mutations in pheochromocytoma/paraganglioma.
abstract: BACKGROUND
  Pheochromocytomas (PCC) and paragangliomas (PGL) may be caused by a germline mutation in 12 different predisposing genes. We previously reported that immunohistochemistry is a useful approach to detect patients harboring SDHx mutations. SDHA immunostaining is negative in SDHA-mutated tumors only, while SDHB immunostaining is negative in samples mutated on all SDHx genes. In some cases of SDHD or SDHC-mutated tumors, a weak diffuse SDHB labeling has however been described.
  
  
  OBJECTIVE
  Here, we addressed whether the same procedure could be applicable to detect patients with germline SDHD mutations, by testing two new commercially available anti-SDHD antibodies.
  
  
  METHODS
  We performed a retrospective study on 170 PGL/PCC in which we investigated SDHD and SDHB expression by immunohistochemistry.
  
  
  RESULTS
  SDHx-mutated PGL/PCC showed a completely negative SDHB staining (23/27) or a weak cytoplasmic background (4/27). Unexpectedly, we observed that SDHD immunohistochemistry was positive in SDHx-deficient tumors and negative in the other samples. Twenty-six of 27 SDHx tumors (including the four weakly stained for SDHB) were positive for SDHD. Among non-SDHx tumors, 138/143 were positive for SDHB and negative for SDHD. Five cases showed a negative immunostaining for SDHB, but were negative for SDHD.
  
  
  CONCLUSIONS
  Our results demonstrate that a positive SDHD immunostaining predicts the presence of an SDHx gene mutation. Because SDHB negative immunostaining is sometimes difficult to interpret in the case of background, the addition of SDHD positive immunohistochemistry will be a very useful tool to predict or validate SDHx gene variants in PGL/PCC.
authors.affiliation: INSERM (M.M., C.B., C.L-L., L.A., A-P.G-R., J.F.), UMR U970, Paris Cardiovascular Research Center-PARCC, F-75015 Paris, France; Université Paris Descartes (M.M., C.B., J.B., C.L-L., L.A., M.S., A-P.G-R., J.F.), Sorbonne Paris Cité, Faculté de Médecine, F-75006 Paris, France; Department of Pathology (L.O., R.d.K.), Erasmus MC Cancer Institute, Erasmus MC, University Medical Center, Rotterdam, The Netherlands; Assistance Publique-Hôpitaux de Paris (AP-HP), Hôpital Européen Georges Pompidou, Département d'Anatomo-Pathologie (C.B.), Services d'Hypertension Artérielle (L.A.), Chirurgie Digestive (F.Z.), and Génétique (A-P.G-R.), F-75015 Paris, France; Assistance Publique-Hôpitaux de Paris (J.B.), Hôpital Cochin, Centre de Référence Maladies Rares de la Surrénale, Service des Maladies Endocriniennes et Métaboliques, F-75014 Paris, France; INSERM (J.B.), U1016, CNRS UMR8104, Département d'Endocrinologie, Métabolisme and Cancer, Institut Cochin, F-75014 Paris, France; Rare Adrenal Cancer Network-Cortico Médullosurrénale Tumeur Endocrine (J.B., A-P.G-R.), Institut National du Cancer, F-75014 Paris, France; Collège de France (X.I.), Centre Interdisciplinaire de Recherche en Biologie, F-75005 Paris, France; INSERM U1050 (X.I.), F-75005 Paris, France; and CNRS UMR7241 (X.I., M.S.), F-75005 Paris, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Menara
authors.forename: Lindsey
authors.initials: L
authors.lastname: Oudijk
authors.forename: Cécile
authors.initials: C
authors.lastname: Badoual
authors.forename: Jérôme
authors.initials: J
authors.lastname: Bertherat
authors.forename: Charlotte
authors.initials: C
authors.lastname: Lepoutre-Lussey
authors.forename: Laurence
authors.initials: L
authors.lastname: Amar
authors.forename: Xavier
authors.initials: X
authors.lastname: Iturrioz
authors.forename: Mathilde
authors.initials: M
authors.lastname: Sibony
authors.forename: Frank
authors.initials: F
authors.lastname: Zinzindohoué
authors.forename: Ronald
authors.initials: R
authors.lastname: de Krijger
authors.forename: Anne-Paule
authors.initials: AP
authors.lastname: Gimenez-Roqueplo
authors.forename: Judith
authors.initials: J
authors.lastname: Favier
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D009154:Mutation; D010235:Paraganglioma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010673:Pheochromocytoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012189:Retrospective Studies; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism*
chemical_list: C491545:SDHD protein, human; D013385:Succinate Dehydrogenase