SDHB/SDHA immunohistochemistry in pheochromocytomas and paragangliomas: a multicenter interobserver variation analysis using virtual microscopy: a Multinational Study of the European Network for the Study of Adrenal Tumors (ENS@T)

• Published in: Modern pathology 2015-06, Vol.28 (6), p.807-821
• Main Authors: Papathomas, Thomas G, Oudijk, Lindsey, Persu, Alexandre, Gill, Anthony J, van Nederveen, Francien, Tischler, Arthur S, Tissier, Frédérique, Volante, Marco, Matias-Guiu, Xavier, Smid, Marcel, Favier, Judith, Rapizzi, Elena, Libe, Rosella, Currás-Freixes, Maria, Aydin, Selda, Huynh, Thanh, Lichtenauer, Urs, van Berkel, Anouk, Canu, Letizia, Domingues, Rita, Clifton-Bligh, Roderick J, Bialas, Magdalena, Vikkula, Miikka, Baretton, Gustavo, Papotti, Mauro, Nesi, Gabriella, Badoual, Cécile, Pacak, Karel, Eisenhofer, Graeme, Timmers, Henri J, Beuschlein, Felix, Bertherat, Jérôme, Mannelli, Massimo, Robledo, Mercedes, Gimenez-Roqueplo, Anne-Paule, Dinjens, Winand NM, Korpershoek, Esther, de Krijger, Ronald R
• Format: Article
• Language: English
• Subjects: 13/1; 13/51; 631/67/1459/1280; 82; 82/1; 82/80; Adrenal Gland Neoplasms - genetics; Biomarkers, Tumor - analysis; Biomarkers, Tumor - genetics; Electron Transport Complex II - analysis; Electron Transport Complex II - genetics; Humans; Immunohistochemistry - standards; Laboratory Medicine; Medicine; Medicine & Public Health; Microscopy - methods; Mutation; Observer Variation; original-article; Paraganglioma - genetics; Pathology; Pheochromocytoma - genetics; Succinate Dehydrogenase - analysis; Succinate Dehydrogenase - genetics; Telepathology - methods
• ISSN: 0893-3952; 1530-0285
• DOI: 10.1038/modpathol.2015.41

Despite the established role of SDHB/SDHA immunohistochemistry as a valuable tool to identify patients at risk for familial succinate dehydrogenase-related pheochromocytoma/paraganglioma syndromes, the reproducibility of the assessment methods has not as yet been determined. The aim of this study was to investigate interobserver variability among seven expert endocrine pathologists using a web-based virtual microscopy approach in a large multicenter pheochromocytoma/paraganglioma cohort ( n =351): (1) 73 SDH mutated, (2) 105 non- SDH mutated, (3) 128 samples without identified SDH-x mutations, and (4) 45 with incomplete SDH molecular genetic analysis. Substantial agreement among all the reviewers was observed either with a two-tiered classification (SDHB κ =0.7338; SDHA κ =0.6707) or a three-tiered classification approach (SDHB κ =0.6543; SDHA κ =0.7516). Consensus was achieved in 315 cases (89.74%) for SDHB immunohistochemistry and in 348 cases (99.15%) for SDHA immunohistochemistry. Among the concordant cases, 62 of 69 (~90%) SDHB-/C-/D-/AF2- mutated cases displayed SDHB immunonegativity and SDHA immunopositivity, 3 of 4 (75%) with SDHA mutations showed loss of SDHA/SDHB protein expression, whereas 98 of 105 (93%) non- SDH -x-mutated counterparts demonstrated retention of SDHA/SDHB protein expression. Two SDHD -mutated extra-adrenal paragangliomas were scored as SDHB immunopositive, whereas 9 of 128 (7%) tumors without identified SDH-x mutations, 6 of 37 (~16%) VHL -mutated, as well as 1 of 21 (~5%) NF1 -mutated tumors were evaluated as SDHB immunonegative. Although 14 out of those 16 SDHB-immunonegative cases were nonmetastatic, an overall significant correlation between SDHB immunonegativity and malignancy was observed ( P =0.00019). We conclude that SDHB/SDHA immunohistochemistry is a reliable tool to identify patients with SDH-x mutations with an additional value in the assessment of genetic variants of unknown significance. If SDH molecular genetic analysis fails to detect a mutation in SDHB-immunonegative tumor, SDHC promoter methylation and/or VHL/NF1 testing with the use of targeted next-generation sequencing is advisable.