Juvenile Spondyloarthropathies and Pediatric Collagen Vascular Disorders

Abstract

The juvenile spondyloarthropathies comprise a group of conditions characterized by inflammation of the sacroiliac joints and of the spine, association with HLA-B27 antigen, and disease onset before age 16. This group encompasses juvenile ankylosing spondylitis, juvenile psoriatic arthritis, reactive arthritis, arthritis associated with inflammatory bowel disease, and the undifferentiated forms of spondyloarthropathy. In addition to the axial skeleton, the juvenile spondyloarthropathies also affect the peripheral joints, mostly in the lower extremities, and prominent enthesopathy is often present. Peripheral arthritis usually predominates during the initial stage and sacroiliitis/spondylitis are late findings, so that children with early-stage juvenile spondyloarthropathies may be incorrectly diagnosed as having classic juvenile idiopathic arthritis. Classic radiographic criteria employed for adult-type disease are fairly insensitive for early diagnosis of juvenile spondyloarthropathies. Therefore, imaging methods such as ultrasonography (US) and magnetic resonance imaging (MRI), which are more sensitive, have become more and more important, given that early diagnosis and timely introduction of treatment are paramount for improved outcome and better quality of life. Pediatric collagen vascular disorders are multisystemic autoimmune diseases of unknown etiology, which are similar in many ways to their adult counterparts. Nonetheless, peculiarities in the presentation and in the evolution of the juvenile forms of collagen diseases make them unique, thus deserving separate study. Even though osteoarticular manifestations are not the more relevant in most patients, some imaging findings are quite typical, and it is important for the radiologist to be acquainted with them. The following paragraphs will discuss the major juvenile spondyloarthropathies and the juvenile forms of dermatomyositis, systemic lupus erythematous, scleroderma, and mixed connective tissue disease.