Clinical ImagesOsteoid Osteoma Mimicking ArthritisCorrêa, Diogo Goulart MD, PhD∗,†; Costa, Flavia Martins MD, PhD∗,‡ Author Information From the ∗Department of Radiology, Clínica de Diagnóstico por Imagem (CDPI)/DASA, Rio de Janeiro †Department of Radiology, Federal Fluminense University, Hospital Universitário Antônio Pedro, Niterói ‡Department of Radiology, Hospital Universitário Clementino Fraga Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. The authors declare no conflict of interest. All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from the patient included in the study. Authors Contributions: D.G.C.: substantial contributions to the design of the work, and interpretation of data; drafting of the work; final approval of the version to be published; and agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. F.M.C.: substantial contributions to the conception and design of the work, analysis, and interpretation of data for the work; drafting of the work; final approval of the version to be published; and agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Correspondence: Diogo Goulart Corrêa, MD, PhD, Clínica de Diagnóstico por Imagem (CDPI), Avenida das Américas, 4666, Rooms 302A, 303, 307, 325, 326, Barra da Tijuca, Rio de Janeiro, Rio de Janeiro, Brazil 2640-102. E-mail: [email protected]. JCR: Journal of Clinical Rheumatology 29(1):p e1-e2, January 2023. | DOI: 10.1097/RHU.0000000000001934 Buy Metrics Abstract Intra-articular osteoid osteoma may simulate arthritis, due to the intra-articular presence of prostaglandin, which leads to synovitis, joint effusion, pain, and high local temperature. Also, intra-articular osteoid osteoma may present with minimum or no cortical thickening. Therefore, a high suspicion is needed for a correct and early diagnosis. Perfusion weighted imaging, such as dynamic contrast-enhanced imaging, can aid in the localization of the tumor nidus, seen as an early arterial-phase focal enhancement after the gadolinium injection, with fast washout, as a result of its hypervascularity. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.