Resumen: Giant 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. Idioma: Inglés DOI: 10.1002/jemt.23976 Año: 2022 Publicado en: MICROSCOPY RESEARCH AND TECHNIQUE 85, 3 (2022), 1065-1074 ISSN: 1059-910X Factor impacto JCR: 2.5 (2022) Categ. JCR: ANATOMY & MORPHOLOGY rank: 5 / 20 = 0.25 (2022) - Q1 - T1 Categ. JCR: MICROSCOPY rank: 2 / 8 = 0.25 (2022) - Q1 - T1 Categ. JCR: BIOLOGY rank: 47 / 92 = 0.511 (2022) - Q3 - T2 Factor impacto CITESCORE: 5.2 - Physics and Astronomy (Q2) - Health Professions (Q1) - Medicine (Q2)