Recognizing Psoriatic Arthritis in Children, Not Always Clear-Cut

More than 290,000 children and teenagers have some form of pediatric arthritis, including psoriatic arthritis, but distinguishing between psoriatic arthritis, juvenile idiopathic arthritis, spondyloarthritis and other types of childhood arthritis is not always easy. [[{"type":"media","view_mode":"media_crop","fid":"41142","attributes":{"alt":"©PuwadolJaturawutthichai/Shutterstock.com","class":"media-image media-image-right","id":"media_crop_9147304352372","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"4295","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"font-size: 13.008px; line-height: 1.538em; float: right;","title":" ","typeof":"foaf:Image"}}]] Since early detection and treatment of pediatric psoriatic arthritis is critical to preventing future joint damage, rheumatologists need diagnostic tools that are more sensitive than X-rays, which can be difficult to read in growing children. These tools increasingly include ultrasound or magnetic resonance imaging. While psoriatic arthritis is more common in adults 40 years old and older, in children, both features may occur simultaneously and in many cases, arthritis may even precede the skin lesions. A peak period for the onset of pediatric psoriatic arthritis is between 11 and 12 years old, with genes, immune system factors and environment believed to play a role in the disease. 

Characterizing Juvenile Psoriatic Arthritis

 Juvenile psoriatic arthritis is among a group of related seronegative, immune-mediated inflammatory arthritic disorders in children that fall under the umbrella term spondyloarthritis. In some children, arthritis can be undifferentiated, meeting criteria for enthesitis-related arthritis, affecting areas where ligaments or muscles attach to bone, often in the joints of the lower extremities. Other children develop more differentiated forms such as juvenile ankylosing spondylitis, psoriatic arthritis or arthritis related to inflammatory bowel disease. But the criteria for those often overlap, according to a review from the

National Institute of Arthritis and Musculoskeletal and Skin Diseases

.   In a study published in the March 2013 issue of

Pediatric Rheumatology

, researchers conducted a study assessing the clinical features and long-term outcomes among 119 young psoriatic arthritis patients.  The patients were studied by four groups of clinical characteristics:  Oligoarticular course, rheumatoid factor negative, either extended oligoarticular or polyarticular, rheumatoid factor positive with polyarticular and enthesitis-related arthritis. Among the group, 55% (n=65) had an oligoarticular-onset.  The researchers wrote:  “We suggest that JPsA may comprise four distinct groups that are similar to non-JPsA JIA regarding presentation, disease course, uveitis associations, response to treatment and outcome.  If other large independent cohorts confirm our findings then we suggest that the presence of psoriasis may have little clinical relevance in the outcome and response to therapy of children with JIA and therefore we may consider psoriasis as an extra-articular manifestation seen in JIA, similar to uveitis, rather a feature requiring a distinct classification grouping.”  

References:

• Colbert RA. Classification of juvenile spondyloarthritis: enthesitis-related arthritis and beyond.Nature Reviews Rheumatology. August 2010. doi:10.1038/nrrheum.2010.103.
• Aviel YB, Tyrrell P, Schneider R, et al.Juvenile Psoriatic Arthritis (JPsA): juvenile arthritis with psoriasis?Pediatric Rheumatology. March 2013. doi:  10.1186/1546-0096-11-11