Juvenile spondyloarthropathy: an important clinical lesson to remember

Abstract

Spondyloarthropathy (SpA) is a group of inflammatory conditions that include spondylitis, sacroiliitis, asymmetrical peripheral arthritis and enthesitis. This condition is known as juvenile SpA when the diagnosis is made in patients up to 16 years of age. Enthesitis is a highly specific feature that occurs more often in juvenile SpA than in the adult form. In contrast to adult onset SpA, the initial manifestation of juvenile SpA rarely presents as inflammatory back pain. Peripheral arthritis is the more common presenting feature. We report a case of a 12-year-old boy who presented with a 1-year history of progressive low back pain, gluteal pain and thigh pain. There were no clinical symptoms of arthropathy of the distal extremities. MRI of the whole spine was performed twice, which, unfortunately, was unyielding. Finally, MRI of the sacroiliac joints revealed asymmetric sacroiliitis as well as enthesitis of the hips and pelvis. Further laboratory data showed negative rheumatoid factor and positive human leucocyte antigen (HLA) B27. A diagnosis of juvenile SpA with sacroiliitis and enthesitis was made. The imaging characteristics of juvenile SpA are highlighted.

Figure 1

MRI of the sacroiliac joints. (A–C) Short τ inversion recovery coronal view showing bilateral asymmetrical periarticular hyperintense signal of the bone marrow (black arrows) indicating active sacroiliitis. At the entheses (white arrows), there is subjacent marrow and peri-enthesial oedema involving the right anterior superior iliac spine, bilateral ischial tuberosities and left greater trochanter. (D) There is synovitis of the left sacroiliac joint (white arrow) and marrow enhancement of the right sacroiliac joint (black arrowhead).

Figure 2

MRI of the sacroiliac joint on coronal view in T2-weighted (A) and T1-weighted images (B). There is joint space widening, articular erosion and subchondral sclerosis of the proximal third of the left sacroiliac joint (black arrow). Periarticular fat deposition (asterisks) is noted at the middle third of the left sacroiliac joint. The changes indicate areas of previous inflammation. Subchondral oedema and articular erosion are observed at the right sacroiliac joint (B).