Thyroid orbitopathy

  • Immune-mediated disorder
  • Associated with hyperthyroidism in Graves disease
  • Can be seen in hypo or euthyroid individuals
  • Orbitopathy often precedes actual thyroid disease
  • M:F = 1:4
  • 4th to 5th decade
  • Most common cause of bilateral or unilateral proptosis
  • Deposition of mucopolysaccharides (hyaluronic acid) within extra-ocular muscles
  • Fusiform muscle enlargement with sparing of tendon
  • Inferior > medial > superior > lateral recti involved
  • Isolated lateral rectus involvement (RARE – look for other causes)
  • Increase of intra-orbital fat and fat stranding giving a dirty appearance 
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Tailor, Tina D., et al. “Orbital neoplasms in adults: clinical, radiologic, and pathologic review.” Radiographics 33.6 (2013): 1739-1758.

LeBedis, Christina A., and Osamu Sakai. “Nontraumatic orbital conditions: diagnosis with CT and MR imaging in the emergent setting.” Radiographics 28.6 (2008): 1741-1753.