The distinct clinical features of giant cell tumor of bone in pagetic and non-pagetic patients are associated with genetic, biochemical and histological differences

// Giuseppina Divisato 1 , Federica Scotto di Carlo 1, 2 , Laura Pazzaglia 3 , Riccardo Rizzo 4 , Domenico A. Coviello 5 , Maria Serena Benassi 3 , Piero Picci 3 , Teresa Esposito 1, 6 and Fernando Gianfrancesco 1 1 Institute of Genetics and Biophysics Adriano Buzzati-Traverso, National Research Council of Italy, Naples, Italy 2 Department of Environmental, Biological and Pharmaceutical Sciences and Technologies (DiSTABiF), University of Campania Luigi Vanvitelli, Caserta, Italy 3 Laboratory of Experimental Oncology, Rizzoli Orthopaedic Institute, Bologna, Italy 4 Institute of Protein Biochemistry, National Research Council of Italy, Naples, Italy 5 Laboratory of Human Genetics, Galliera Hospital, Genova, Italy 6 IRCCS INM Neuromed, Pozzilli, Italy Correspondence to: Fernando Gianfrancesco, email: fernando.gianfrancesco@igb.cnr.it Keywords: bone cancer, GCT, pagetic GCT, ZNF687, H3F3A Received: August 04, 2016     Accepted: May 23, 2017     Published: June 27, 2017 ABSTRACT Giant Cell Tumor of Bone (GCT) is a tumor characterized by neoplastic mesenchymal stromal cells and a high number of osteoclast-like multinucleated giant cells. Rarely, GCT could arise in bones affected by Paget’s disease of bone (GCT/PDB). Although it is already known that GCT/PDB and GCT show a different clinical profile regarding the age-onset and skeletal localization, our deep clinical comparison between the two GCT/PDB and GCT cohorts, permitted us to identify additional differences (e.g. focality, ALP serum levels, the 5-year survival rate and the familial recurrence), strongly suggesting a different molecular basis. Accordingly, driver somatic mutations in H3F3A and IDH2 were described in GCT patients, while we recently identified a germline mutation in ZNF687 as the genetic defect of GCT/PDB patients. Here, we detected H3F3A mutations in our GCT cohort, confirming its molecular screening as the elected diagnostic tool, and then we excluded the two-hit in H3F3A and IDH2 as the trigger event for the GCT/PDB development. Importantly, we also identified an alternative biochemical profile with GCT/PDB not exhibiting the up-regulation of the GCT marker FGFR2IIIc . Finally, our histological analysis also showed a different appearance of the two forms of the tumor, with GCT/PDB showing a higher number of osteoclast-like giant cells (twice), with an abnormal number of nuclei per cell, corroborating its different behaviour in terms of neoplastic properties. We demonstrated that the distinct clinical features of pagetic and conventional GCT are associated with different genetic background, resulting in a specific biochemical and histological behaviour of the tumour.