Discitis--a rare early symptom of ankylosing spondylitis.

This case report describes a patient who suffered from backache at the age of 12 years. The initial diagnosis was Scheuermann's disease but repeated examinations showed a progressive discitis, without signs of arthritis of the sacro-iliac joints. There was also a recurring effusion of the left knee. Three years later the clinical and radiological evaluation showed irreversible immobilisation of the dorsolumbar spine, whereas the sacro-iliac joints were mildly affected. Discitis seems to be a rare early symptom of ankylosing spondylitis.