New clinical and radiographic features of the seronegative spondyloarthropathies

The influence of patient characteristics, disease variables, and HLA alleles on the development of radiographically evident sacroiliitis in juvenile idiopathic arthritis

OBJECTIVE

To assess the frequency of sacroiliitis and the radiographic and clinical outcome in juvenile idiopathic arthritis (JIA) and determine patient characteristics, early disease variables, and genetic markers that predict development of sacroiliitis.

METHODS

We performed a retrospective cohort study of 314 (79%) of the 400 JIA patients first admitted to the hospital between 1980 and 1985. The participants were examined after a median disease duration of 14.9 years (range 11.7-25.1). Radiographs of the sacroiliac joints, hips, ankles, and tarsi were obtained and studied in a blinded manner by 2 radiologists. The presence of HLA-DRB1 and DPB1 alleles was determined by genotyping and that of HLA-B27 by serologic testing. Variables relating to the onset and course of the disease were obtained by chart reviews.

RESULTS

Twenty (6%) of the JIA patients developed radiographic sacroiliitis according to the New York criteria. In 9 patients (45%), sacroiliitis had not been demonstrated before the followup examination. At followup, spinal flexion (lateral and anterior) was reduced in 70-75% of patients with sacroiliitis and in 30-35% of those without sacroiliitis. Compared with the JIA patients without sacroiliitis, those with sacroiliitis more frequently had inflammatory back pain, enthesitis, radiographic changes in the hips and calcanei, erosions of any peripheral joint, and uveitis. Predictors of sacroiliitis were HLA-B27, absence of DPB1*02, hip joint involvement within the first 6 months, and disease onset after age 8 years. The following factors were more common among patients in whom sacroiliitis developed than in other JIA patients: DRB1*04, male sex, family history of ankylosing spondylitis, psoriasis, inflammatory back pain, and enthesitis within the first 6 months.

CONCLUSION

In the current study, radiographically evident sacroiliitis had developed in 6% of JIA patients after a median disease duration of 14.9 years. HLA-B27, absence of DPB1*02, late onset of disease, and early hip involvement were predictors of sacroiliitis.

Seronegative spondyloarthropathy associated with megarectum

In this report we describe a case of a 19-year-old man with a two-year history of polyarthritis affecting the lower limbs and dactylitis of the toes. His clinical picture fulfilled the new European diagnostic criteria for spondyloarthropathies. Systemic examination revealed a big mass in the left iliac fossa that was found to be due to an acquired functional megacolon. Complete remission of the joint involvement was obtained by treating the bowel disease.

The pathogenetic aspects of spondyloarthropathies from the point of view of HLA-B27

The association of HLA-B27 and seronegative spondyloarthropathies, especially ankylosing spondylitis has been known for almost two decades. The spontaneous development of spondyloarthropathy like joint disease in HLA-B27 transgenic rats verifies the suspicion that the HLA-B27 antigens are directly responsible for disease development. With the recently revealed crystal structure of HLA-B27 and understanding of the class I molecule in general, a new hypothesis can be formulated based on the assumption that the pathogenesis of these diseases is a subversion of the physiological function.