doi:10.1002/jemt.23976engCastiella, T.Iruzubieta, P.Monleón, E.Cardiel, M. J.Gómez-Vallejo, J.Monzón, M.Junquera, M. C.Stromal cells of giant cell tumor of bone show primary cilia in giant cell tumor of boneART-2022-126938Giant cell tumor of bone (GCTB) is a locally aggressive primary bone neoplasm com-posed by tumoral stromal cells (SCs) and a reactive component that consists ofmonocytic/histiocytic cells that give rise by fusion to osteoclast-like multinucleatedcells. Recently, specific Histone 3.3 mutations have been demonstrated in SCs ofGCTB. Many of the pathways related to bone proliferation and regulation depend onthe primary cilium, a microtubule-based organelle that protrudes outside the cell andacts as a sensorial antenna. In the present work, we aimed to study the presence androle of primary cilia in GCTB. Ultrastructural, immunohistochemical, and immunofluo-rescence studies were performed in order to demonstrate, for the first time, that theprimary cilium is located in spindle-shaped SCs of GCTB. Moreover, we showedHedgehog (Hh) signaling pathway activation in these cells. Hence, primary cilia mayplay a relevant role in GCTB tumorogenesis through Hh signaling activation in SCs.2022http://zaguan.unizar.es/record/11879210.1002/jemt.23976http://zaguan.unizar.es/record/118792oai:zaguan.unizar.es:118792MICROSCOPY RESEARCH AND TECHNIQUE 85, 3 (2022), 1065-1074All rights reservedhttp://www.europeana.eu/rights/rr-f/info:eu-repo/semantics/openAccess