Juvenile ankylosing spondylitis, its clinical features and HLA-B27.

We have experienced six patients of juvenile ankylosing spondylitis. Their chief complaints were polyarthralgia or coxalgia, however, any pain or stiffness in lumbar regions was absent. These clinical features were atypical for those of ankylosing spondylitis, and much more like those of a peripheral arthropathy such as juvenile rheumatoid arthritis. After a long-term follow-up, all the patients showed definite clinical features of ankylosing spondylitis. HLA-B27 was found in 4 out of 6 cases. This frequency is almost equal to that of adult ankylosing spondylitis patients. HLA typing was very important in the early diagnosis.