en روماتولوژی Rheumatology گزارش مورد Case Report <strong>Background</strong>: Ankylosing spondylitis (AS) and multiple sclerosis (MS) rarely coexist. Diagnosing and managing these conditions simultaneously can be challenging.<br> <strong>Case Presentation</strong>: The current study reported the case of a 42-year-old man diagnosed with AS who later developed MS during follow-up.<br> <strong>Conclusion</strong>: While both AS and MS are autoimmune diseases, experiencing both conditions simultaneously is uncommon. Selecting an effective treatment plan tailored to individuals with both diseases is crucial.&nbsp; Ankylosing spondylitis (AS), Multiple sclerosis (MS) 251 254 http://jros.iums.ac.ir/browse.php?a_code=A-10-1597-2&slc_lang=en&sid=1 Parisa Delkash parisa.delkash@yahoo.com 10031947532846007670 10031947532846007670 No Clinical Research Development Unit, Imam Hossein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Minoo Heidari Almasi minooheidari.mh@gmail.com 10031947532846007671 10031947532846007671 Yes Clinical Research Development Unit, Imam Hossein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Mohammadreza Chehrassan morchehrasan@yahoo.com 10031947532846007672 10031947532846007672 No Department of Orthopedics, Bone and Joint Reconstruction Research Center, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. Seyed Alireza Ebadi s.alireza_ebadi@yahoo.com 10031947532846007673 10031947532846007673 No Department of Internal Medicine, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.