Pediatric Dermatomyositis

  • Etiology: Autoimmune inflammatory myositis with multisystemic features
  • Imaging Radiograph: Soft tissue calcification is complication of longstanding or severe disease and is best seen on radiographs
  • Imaging MRI:
    — SITR and T2WI: Hyperintensity that is widespread and diffuse which is bilateral and often symmetrical in proximal muscles without atrophy and is anterior compartment dominant (vastus lateralis and intermedialis)
  • DDX:
  • Complications:
  • Treatment:
  • Clinical:
    — Puritic rash on exposed skin especially extensor surfaces (heliotrope rash)
    — Proximal weakness

Radiology Cases of Dermatomyositis

MRI of dermatomyositis
Axial T2 (upper left) and coronal STIR (upper right) MRI without contrast of the pelvis show increased signal intensity in all of the muscles in the pelvis and thighs while the coronal T1 without contrast (lower left) and coronal T1 with contrast (lower right) MRI of the pelvis show enhancement in all of the muscles in the pelvis and thighs.
MRI of dermatomyositis
Coronal (above) and axial (below left) T2 MRI of the pelvis along with axial T2 MRI of the thighs (below right) shows diffuse, bilateral, symmetrical bright signal in the visualized muscles representing intramuscular edema in the quadratus lumborum, gluteal, and proximal thigh hamstring muscles.
MRI of dermatomyositis
Axial T2 MRI through the hips (above) shows small patchy areas of increased T2 signal bilaterally and symmetrically in the gluteus muscles and in the subcutaneous tissues of the lateral and posterior thighs which show mild enhancement on axial T1 MRI with contrast (below).