Many patients have experienced that sometimes doctors say “you have spondyloarthritis” and sometimes they meet another doctor and say “you have ankylosing spondylitis”. This literally different disease inevitably leads patients to question the different statements of different doctors, how can one doctor say the same thing? In the face of such questions, it is sometimes difficult for doctors to explain clearly in a few sentences, especially in the short time available for outpatient visits, so when the explanation is clear and the patient understands, it is impossible to finish the work. Here is a brief breakdown of the concepts related to spondyloarthritis, which I hope will be helpful. Spondyloarthritis (SpA), previously known as seronegative spondyloarthropathy or spondyloarthropathy (SpA), is a group of chronic inflammatory rheumatic diseases, noting that it is a group of diseases, which means that there are several diseases under the name spondyloarthritis. Spondyloarthritis is divided into medial spondyloarthritis and peripheral spondyloarthritis; medial spondyloarthritis includes non-radiographic medial spondyloarthritis and ankylosing spondylitis, that is, ankylosing spondylitis is both medial spondyloarthritis and spondyloarthritis. Similarly, psoriatic arthritis is also peripheral spondyloarthritis or spondyloarthritis. The clinical manifestations of this group of diseases included in spondyloarthritis are not distinctly separate and sometimes cross over. For example, ankylosing spondylitis can present with acute anterior uveitis, as well as enterocolitis and a psoriatic rash; similarly, psoriatic arthritis can present with low back pain and sacroiliac arthritis. Ankylosing spondylitis is a type of spondyloarthritis that involves the mid-axis joints and has radiographic changes in the sacroiliac joints. By understanding the relationship between these groups of diseases, you will not think that your doctor will say one thing at a time and another at a time.