A case of ankylosing spondylitis presenting with fever of unknown origin diagnosed as aortitis: A case report

KEY CLINICAL MESSAGE: Clinicians should be aware of rare manifestations of AS, while considering a low threshold for screening vascular involvement in an axial SpA/nrxSpA/AS presenting with unexplained fevers and significant constitutional symptoms and elevated markers. ABSTRACT: Ankylosing spondylitis (AS) is a chronic inflammatory disease from the spondyloarthritis complex, which usually affects young men and primarily involves sacroiliac joints and the spine. It can also present with non‐joint involvement, such as cardiovascular manifestations. Aortitis is a rare yet critical cardiovascular complication associated with AS, which can lead to life‐threatening outcomes when undiagnosed. Here we report a 34‐year‐old man with intermittent fevers and significant weight loss, myalgia, and arthralgia for 1 year before being referred to our hospital due to undefinable causes despite multiple diagnostic efforts. The patient presented with elevated inflammatory markers and involvement of sacroiliac joints in favor of the AS. A positron emission tomography scan was also done to rule out underlying malignancy, which led to the detection of inflammation in ascending aorta, compatible with aortitis. The patient was treated with nonsteroidal anti‐inflammatory drugs, prednisolone, and infliximab, and his signs and symptoms significantly improved. Our case reports a rare but substantial complication of AS, in a young patient without a history of prolonged disease presenting with unspecific manifestations. The implantation of a thorough examination of AS patients, including cardiac examinations, could contribute to faster and more efficient diagnosis and treatment.