Which statement best describes the hallmark feature of Ankylosing Spondylitis and its typical demographic?

• A. Joints swelling in hands; Males; Childhood
• B. Upward migration of sacroiliitis; Males; Late teens to early 20s
• C. Erosion of the acromioclavicular joint; Females; 40s
• D. Posterior neck pain; Both genders; 60s

Answer: (B)

Inflammatory involvement of the axial skeleton starting with the sacroiliac joints is the defining feature of Ankylosing Spondylitis. The disease often begins in adolescence or early adulthood and is particularly common in males, aligning with onset in the late teens to early 20s. The sacroiliitis can progressively affect higher segments of the spine, leading to reduced mobility as the spine fuses over time. This combination—sacroiliitis that raises its involvement upward along the spine and a typical patient demographic of young men—best matches the description. Other scenarios, like peripheral hand joint swelling, AC joint erosion, or neck pain in older individuals, do not fit the classic axial, early-onset pattern seen in Ankylosing Spondylitis.