Dense osteitis does not result in a positive B27. B27 positivity is a diagnostic indicator of ankylosing spondylitis. Patients with ankylosing spondylitis may show B27 positivity when tested. Dense osteitis, or dense iliitis, is an osteoarthropathy with increased bone density in the auricular joint between the sacrum and the ilium. The exact cause of the disease is unclear, and it may be related to infection, trauma, or pregnancy, and is not part of ankylosing spondylitis, so it does not lead to B27 positivity. Dense osteitis may cause pain in the lumbosacral and lower lumbar regions, and occasionally radiating pain in the posterior femur and lower buttocks. Currently, conservative treatment is the mainstay of clinical care. When dense osteitis causes persistent pain, joint fusion surgery may be considered. Dense osteitis needs to go to the hospital in time, under the guidance of the doctor standardized treatment.