Original ArticlesMutation Analysis of H3F3A and H3F3B as a Diagnostic Tool for Giant Cell Tumor of Bone and ChondroblastomaCleven, Arjen H.G. MD, PhD; Höcker, Saskia MSc; Briaire-de Bruijn, Inge MSc; Szuhai, Karoly MD, PhD; Cleton-Jansen, Anne-Marie PhD; Bovée, Judith V.M.G. MD, PhDAuthor Information Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website, www.ajsp.com. Conflicts of Interest and Source of Funding: The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no. 278742 (Eurosarc). The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Judith V.M.G. Bovée, MD, PhD, Department of Pathology, Leiden University Medical Center, PO Box 9600, L1-Q, 2300 RC Leiden, The Netherlands (e-mail: [email protected]). The American Journal of Surgical Pathology: November 2015 - Volume 39 - Issue 11 - p 1576-1583 doi: 10.1097/PAS.0000000000000512 Buy SDC Metrics Abstract Specific H3F3A driver mutations and IDH2 mutations were recently described in giant cell tumor of bone (GCTB) and H3F3B driver mutations in chondroblastoma; these may be helpful as a diagnostic tool for giant cell–containing tumors of the bone. Using Sanger sequencing, we determined the frequency of H3F3A, H3F3B, IDH1, and IDH2 mutations in GCTBs (n=60), chondroblastomas (n=12), and other giant cell–containing tumors (n=24), including aneurysmal bone cyst, chondromyxoid fibroma, and telangiectatic osteosarcoma. To find an easy applicable marker for H3F3A mutation status, H3K36 trimethylation and ATRX expression were correlated with H3F3A mutations. In total, 69% of all GCTBs harbored an H3F3A (G34W/V) mutation compared with 0% of all other giant cell–containing tumors (P<0.001), whereas 70% of chondroblastomas showed an H3F3B (K36M) mutation compared with 0% of other giant cell–containing tumors (P<0.001). Diffuse H3K36 trimethylation positivity was more often seen in mutated H3F3A GCTBs compared with other giant cell–containing tumors (P=0.005). ATRX protein expression was not correlated with H3F3A mutation status. Hotspot mutations in IDH1 or IDH2 were absent. Our results show that H3F3A and H3F3B mutation analysis appears to be a highly specific, although less sensitive, diagnostic tool for the distinction of GCTB and chondroblastoma from other giant cell–containing tumors. Although H3K36 trimethylation and ATRX immunohistochemistry cannot be used as surrogate markers for H3F3A mutation status, mutations in H3F3A are associated with increased H3K36 trimethylation, suggesting that methylation at this residue may play a role in the etiology of the disease. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.