Idiopathic orbital inflammation

Changed by Calum Worsley, 18 Jul 2022

Back to revision history

Disclosures - updated 12 Apr 2022: Nothing to disclose

Updates to Article Attributes

Body was changed:

Show markup changes

Idiopathic orbital inflammation (IOI), also known as orbital pseudotumour and non-specific orbital inflammation (NSOI), is an idiopathic inflammatory condition that most commonly involves the extraocular muscles. Less commonly there is inflammatory change involving the uvea, sclera, lacrimal gland, and retrobulbar soft tissue.

The exact aetiology is not known but an association with many inflammatory/autoimmune diseases is reported.

Terminology

Many terms are used interchangeably in the literature to refer to idiopathic orbital inflammation including orbital pseudotumour, non-specific orbital inflammation and orbital inflammatory syndrome.

Clinical presentation

Patients typically present with rapid-onset, usually unilateral (~90% of cases), painful proptosis and diplopia. Idiopathic orbital inflammation is a diagnosis of exclusion; atypical presentation, poor response to treatment with corticosteroid and recurrence should prompt biopsy to exclude other diseases.

Pathology

Histologically acute lesions demonstrate lymphocytes (which can be mistaken for orbital lymphoma), plasma cells, and giant cell infiltration.

Classification

Division into a number of subgroups according to location has been proposed:

L acrimal pseudotumour (dacryoadenitis)
Anterior pseudotumour: in the immediate retrobulbar fat
Posterior pseudotumour: in the fat at the orbital apex; distinguished from Tolosa-Hunt syndrome in that the cavernous sinus is spared
Myositic pseudotumour (myositis): predominantly ~~involve~~involves the ~~EOMs~~extraocular muscles and therefore mimic thyroid-associated orbitopathy (TAO) but unlike TAO it also involves the tendons
Optic perineuritis: involvement of the optic nerve sheath
Diffuse pseudotumour: affecting multiple compartments

Associations

The condition has been associated with other inflammatory and autoimmune conditions:

iI gG4-related disease, now recognised as a separate entity: IgG4-related orbital disease
s arcoidosis
g ranulomatosis with polyangiitis
s ystemic lupus erythematosus (SLE)
p olyarteritis nodosa (PAN)
d ermatomyositis
r heumatoid arthritis (RA)
s clerosing cholangitis
rR iedel thyroiditis
m ediastinal fibrosis

Radiographic features

Imaging demonstrates enlargement of the muscle belly of one (or more) extraocular muscles typically with the involvement of tendinous insertions. Involvement of the tendinous insertion distinguishes the ~~IOI~~idiopathic orbital inflammation from thyroid-associated orbitopathy (TAO) in which the insertion point is spared. However, sparing of the anterior tendon does not exclude the diagnosis of idiopathic orbital myositis ⁷.

Additional inflammation can be seen in surrounding tissues, including the orbital fat, lacrimal gland, and optic nerve sheath.

It can appear as an infiltrative mass and extends outside of the orbit via superior or inferior orbital fissures. Extension into the cavernous sinus, meninges, and dura can occur. It is most commonly unilateral but can be bilateral in 25% of cases.

MRI

Reported signal characteristics include:

T1: affected region typically isointense (to ~~extra-ocular~~extraocular muscles) ¹ but can also be hypointense ^1-3
T2: affected region typically hypointense due to fibrosis and with more progression of fibrosis it becomes more hypointense, but the signal can also be iso- to hyperintense to extra-ocular muscles ²
T1 C+ (Gd): moderate to a marked diffuse enhancement

Treatment and prognosis

Most cases resolve rapidly with treatment (usually corticosteroids suffice) although in a subset with more chronic progression chemotherapy and radiotherapy may be required. A degree of residual fibrosis can be demonstrated, especially in the more refractory cases.

History and etymology

The disease was first described by Birch-Hirschfeld et al. in 1905 ⁶. They also introduced the term orbital pseudotumour afterward in 1930 ⁷.

Differential diagnosis

One of the main differential diagnoses of idiopathic orbital inflammation is orbital lymphoma. There is considerable overlap between these entities both clinically and radiologically. However, orbital lymphoma usually presents as a progressive orbitopathy rather than acutely, is more often bilateral, shows lower values on ADC, and does not respond to corticosteroid.

Other imaging differential considerations include:

o rbital cellulitis: usually associated with a subperiosteal abscess from adjacent sinusitis or with a previous history of trauma/dental procedure
Tthyroid-associated orbitopathy (TAO): spares the tendinous insertions and not usually painful
Tolosa-Hunt syndrome: related condition with the involvement of the cranial nerves in the cavernous sinus and resulting ophthalmoplegia
g ranulomatosis with polyangiitis: bilateral involvement of the paranasal sinuses and orbits associated with osseous destruction
o rbital sarcoidosis
o rbital metastases
o rbital rhabdomyosarcoma

-<li>Myositic pseudotumour (myositis): predominantly involve the EOMs and therefore mimic <a href="/articles/thyroid-associated-orbitopathy-1">thyroid-associated orbitopathy (TAO)</a> but unlike TAO it also involves the tendons</li>
+<li>Myositic pseudotumour (myositis): predominantly involves the extraocular muscles and therefore mimic <a href="/articles/thyroid-associated-orbitopathy-1">thyroid-associated orbitopathy (TAO)</a> but unlike TAO it also involves the tendons</li>
-<a title="IgG4-related disease" href="/articles/igg4-related-disease">i</a><a href="/articles/igg4-related-disease">gG4-related disease</a>, now recognised as a separate entity: <a href="/articles/igg4-related-orbital-disease">IgG4-related orbital disease</a>
+<a title="IgG4-related disease" href="/articles/igg4-related-disease">I</a><a href="/articles/igg4-related-disease">gG4-related disease</a>, now recognised as a separate entity: <a href="/articles/igg4-related-orbital-disease">IgG4-related orbital disease</a>
~~-<a title="Sarcoidosis" href="/articles/sarcoidosis-1">s</a><a href="/articles/sarcoidosis-1">arcoidosis</a>~~
+<a href="/articles/sarcoidosis-1">s</a><a href="/articles/sarcoidosis-1">arcoidosis</a>
-<a title="Granulomatosis with polyangiitis" href="/articles/granulomatosis-with-polyangiitis">g</a><a title="Granulomatosis with polyangiitis (breast manifestations)" href="/articles/granulomatosis-with-polyangiitis-breast-manifestations-1">ranulomatosis with polyangiitis</a>
+<a href="/articles/granulomatosis-with-polyangiitis">g</a><a href="/articles/granulomatosis-with-polyangiitis-breast-manifestations-1">ranulomatosis with polyangiitis</a>
~~-<a title="Systemic lupus erythematosus (SLE)" href="/articles/systemic-lupus-erythematosus">s</a><a href="/articles/systemic-lupus-erythematosus">ystemic lupus erythematosus (SLE)</a>~~
+<a href="/articles/systemic-lupus-erythematosus">s</a><a href="/articles/systemic-lupus-erythematosus">ystemic lupus erythematosus (SLE)</a>
~~-<a title="Polyarteritis nodosa (PAN)" href="/articles/polyarteritis-nodosa-1">p</a><a href="/articles/polyarteritis-nodosa-1">olyarteritis nodosa (PAN)</a>~~
+<a href="/articles/polyarteritis-nodosa-1">p</a><a href="/articles/polyarteritis-nodosa-1">olyarteritis nodosa (PAN)</a>
~~-<a title="Dermatomyositis" href="/articles/dermatomyositis">d</a><a href="/articles/dermatomyositis">ermatomyositis</a>~~
+<a href="/articles/dermatomyositis">d</a><a href="/articles/dermatomyositis">ermatomyositis</a>
~~-<a title="Rheumatoid arthritis (RA)" href="/articles/rheumatoid-arthritis">r</a><a href="/articles/rheumatoid-arthritis">heumatoid arthritis (RA)</a>~~
+<a href="/articles/rheumatoid-arthritis">r</a><a href="/articles/rheumatoid-arthritis">heumatoid arthritis (RA)</a>
~~-<a title="Sclerosing cholangitis" href="/articles/sclerosing-cholangitis">s</a><a href="/articles/sclerosing-cholangitis">clerosing cholangitis</a>~~
+<a href="/articles/sclerosing-cholangitis">s</a><a href="/articles/sclerosing-cholangitis">clerosing cholangitis</a>
~~-<a title="Riedel thyroiditis" href="/articles/riedel-thyroiditis">r</a><a href="/articles/riedel-thyroiditis">iedel thyroiditis</a>~~
+<a title="Riedel thyroiditis" href="/articles/riedel-thyroiditis">R</a><a href="/articles/riedel-thyroiditis">iedel thyroiditis</a>
~~-<a title="mediastinal fibrosis" href="/articles/mediastinal-fibrosis">m</a><a href="/articles/mediastinal-fibrosis">ediastinal fibrosis</a>~~
+<a href="/articles/mediastinal-fibrosis">m</a><a href="/articles/mediastinal-fibrosis">ediastinal fibrosis</a>
-</ul><h4>Radiographic features</h4><p>Imaging demonstrates enlargement of the muscle belly of one (or more) extraocular muscles typically with the involvement of tendinous insertions. Involvement of the tendinous insertion distinguishes the IOI from <a href="/articles/thyroid-associated-orbitopathy-1">thyroid-associated orbitopathy (TAO)</a> in which the insertion point is spared. However, sparing of the anterior tendon does not exclude the diagnosis of idiopathic orbital myositis <sup>7</sup>.</p><p>Additional inflammation can be seen in surrounding tissues, including the orbital fat, <a href="/articles/lacrimal-gland">lacrimal gland</a>, and optic nerve sheath.</p><p>It can appear as an infiltrative mass and extends outside of the orbit via superior or inferior orbital fissures. Extension into the <a href="/articles/cavernous-sinus">cavernous sinus</a>, <a href="/articles/meninges">meninges</a>, and <a href="/articles/dura-mater">dura</a> can occur. It is most commonly unilateral but can be bilateral in 25% of cases.</p><h5>MRI</h5><p>Reported signal characteristics include:</p><ul>
+</ul><h4>Radiographic features</h4><p>Imaging demonstrates enlargement of the muscle belly of one (or more) extraocular muscles typically with the involvement of tendinous insertions. Involvement of the tendinous insertion distinguishes the idiopathic orbital inflammation from <a href="/articles/thyroid-associated-orbitopathy-1">thyroid-associated orbitopathy (TAO)</a> in which the insertion point is spared. However, sparing of the anterior tendon does not exclude the diagnosis of idiopathic orbital myositis <sup>7</sup>.</p><p>Additional inflammation can be seen in surrounding tissues, including the orbital fat, <a href="/articles/lacrimal-gland">lacrimal gland</a>, and optic nerve sheath.</p><p>It can appear as an infiltrative mass and extends outside of the orbit via superior or inferior orbital fissures. Extension into the <a href="/articles/cavernous-sinus">cavernous sinus</a>, <a href="/articles/meninges">meninges</a>, and <a href="/articles/dura-mater">dura</a> can occur. It is most commonly unilateral but can be bilateral in 25% of cases.</p><h5>MRI</h5><p>Reported signal characteristics include:</p><ul>
~~-<strong>T1:</strong> affected region typically isointense (to extra-ocular muscles) <sup>1</sup> but can also be hypointense <sup>1-3</sup>~~
+<strong>T1:</strong> affected region typically isointense (to extraocular muscles) <sup>1</sup> but can also be hypointense <sup>1-3</sup>
-<a href="/articles/orbital-infection">O</a><a href="/articles/orbital-infection">rbital cellulitis</a>: usually associated with a subperiosteal abscess from adjacent sinusitis or with a previous history of trauma/dental procedure </li>
~~-<li>T<a href="/articles/thyroid-associated-orbitopathy-1">hyroid-associated orbitopathy (TAO)</a>: spares the tendinous insertions and not usually painful</li>~~
+<a title="Orbital cellulitis" href="/articles/orbital-infection">o</a><a href="/articles/orbital-infection">rbital cellulitis</a>: usually associated with a subperiosteal abscess from adjacent sinusitis or with a previous history of trauma/dental procedure </li>
+<li>
+<a title="Thyroid-associated orbitopathy" href="/articles/thyroid-associated-orbitopathy-1">t</a><a href="/articles/thyroid-associated-orbitopathy-1">hyroid-associated orbitopathy (TAO)</a>: spares the tendinous insertions and not usually painful</li>
-<a href="/articles/granulomatosis-with-polyangiitis">G</a><a href="/articles/granulomatosis-with-polyangiitis-orbital-manifestations">ranulomatosis with polyangiitis</a>: bilateral involvement of the paranasal sinuses and orbits associated with osseous destruction</li>
+<a title="Granulomatosis with polyangiitis (orbital manifestations)" href="/articles/granulomatosis-with-polyangiitis-orbital-manifestations">g</a><a href="/articles/granulomatosis-with-polyangiitis-orbital-manifestations">ranulomatosis with polyangiitis</a>: bilateral involvement of the paranasal sinuses and orbits associated with osseous destruction</li>
~~-<a href="/articles/sarcoidosis-orbital-manifestations-1">O</a><a href="/articles/orbital-sarcoidosis">rbital sarcoidosis</a>~~
+<a title="Orbital sarcoidosis" href="/articles/sarcoidosis-orbital-manifestations-1">o</a><a href="/articles/orbital-sarcoidosis">rbital sarcoidosis</a>
~~-<a href="/articles/orbital-metastasis">O</a><a href="/articles/orbital-metastases">rbital metastases</a>~~
+<a title="Orbital metastases" href="/articles/orbital-metastasis">o</a><a href="/articles/orbital-metastases">rbital metastases</a>
~~-<a href="/articles/rhabdomyosarcoma-orbit">O</a><a href="/articles/rhabdomyosarcoma-orbit">rbital rhabdomyosarcoma</a>~~
+<a title="Orbital rhabdomyosarcoma" href="/articles/rhabdomyosarcoma-orbit">o</a><a href="/articles/rhabdomyosarcoma-orbit">rbital rhabdomyosarcoma</a>

References changed:

1. Schaffler G, Simbrunner J, Lechner H et al. Idiopathic Sclerotic Inflammation of the Orbit with Left Optic Nerve Compression in a Patient with Multifocal Fibrosclerosis. AJNR Am J Neuroradiol. 2000;21(1):194-7. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7976342">PMC7976342</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/10669249">Pubmed</a>
2. Kapur R, Sepahdari A, Mafee M et al. MR Imaging of Orbital Inflammatory Syndrome, Orbital Cellulitis, and Orbital Lymphoid Lesions: The Role of Diffusion-Weighted Imaging. AJNR Am J Neuroradiol. 2009;30(1):64-70. <a href="https://doi.org/10.3174/ajnr.A1315">doi:10.3174/ajnr.A1315</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/18842758">Pubmed</a>
3. Wolfgang Dähnert. Radiology Review Manual. (2003) ISBN: 9780781738958 - <a href="http://books.google.com/books?vid=ISBN9780781738958">Google Books</a>
4. Nugent R, Rootman J, Robertson W, Lapointe J, Harrison P. Acute Orbital Pseudotumors: Classification and CT Features. AJR Am J Roentgenol. 1981;137(5):957-62. <a href="https://doi.org/10.2214/ajr.137.5.957">doi:10.2214/ajr.137.5.957</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/6975021">Pubmed</a>
7. Dresner S, Rothfus W, Slamovits T, Kennerdell J, Curtin H. Computed Tomography of Orbital Myositis. AJR Am J Roentgenol. 1984;143(3):671-4. <a href="https://doi.org/10.2214/ajr.143.3.671">doi:10.2214/ajr.143.3.671</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/6331757">Pubmed</a>
1. Schaffler GJ, Simbrunner J, Lechner H et-al. Idiopathic sclerotic inflammation of the orbit with left optic nerve compression in a patient with multifocal fibrosclerosis. AJNR Am J Neuroradiol. 2000;21 (1): 194-7. <a href="http://www.ajnr.org/cgi/content/full/21/1/194">AJNR Am J Neuroradiol (full text)</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/10669249">Pubmed citation</a><div class="ref_v2"></div>
2. Kapur R, Sepahdari AR, Mafee MF et-al. MR imaging of orbital inflammatory syndrome, orbital cellulitis, and orbital lymphoid lesions: the role of diffusion-weighted imaging. AJNR Am J Neuroradiol. 2009;30 (1): 64-70. <a href="http://dx.doi.org/10.3174/ajnr.A1315">doi:10.3174/ajnr.A1315</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/18842758">Pubmed citation</a><div class="ref_v2"></div>
3. Dähnert W. Radiology review manual. Lippincott Williams & Wilkins. (2007) ISBN:0781738954. <a href="http://books.google.com/books?vid=ISBN0781738954">Read it at Google Books</a> - <a href="http://www.amazon.com/gp/product/0781738954?ie=UTF8&tag=radiopaediaor-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0781738954">Find it at Amazon</a><div class="ref_v2"></div>
4.. Nugent RA, Rootman J, Robertson WD et-al. Acute orbital pseudotumors: classification and CT features. AJR Am J Roentgenol. 1981;137 (5): 957-62. <a href="http://www.ajronline.org/cgi/content/abstract/137/5/957">AJR Am J Roentgenol (abstract)</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/6975021">Pubmed citation</a><div class="ref_v2"></div>
7. Dresner SC, Rothfus WE, Slamovits TL, Kennerdell JS, Curtin HD. Computed tomography of orbital myositis. (1984) AJR. American journal of roentgenology. 143 (3): 671-4. <a href="https://doi.org/10.2214/ajr.143.3.671">doi:10.2214/ajr.143.3.671</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/6331757">Pubmed</a> <span class="ref_v4"></span>

ADVERTISEMENT: Supporters see fewer/no ads

{"current_user":null,"inclusions":[{"imageId":13285,"studyId":6761,"caseSlug":"orbital-pseudotumour","caption":"Case 1: coronal","thumbnail":"https://prod-images-static.radiopaedia.org/images/13285/e58a4b52cda3ea186ae63f22472f77_big_gallery.jpeg","isStack":false,"diagnosticCertainty":"confirmed_unsubstantiated"},{"imageId":13282,"studyId":6761,"caseSlug":"orbital-pseudotumour","caption":"Case 1: axial","thumbnail":"https://prod-images-static.radiopaedia.org/images/13282/4a42c8aa815623d112a9700cc752ca_big_gallery.jpeg","isStack":false,"diagnosticCertainty":"confirmed_unsubstantiated"},{"imageId":4326561,"studyId":24312,"caseSlug":"orbital-pseudotumour-2","caption":"Case 2","thumbnail":"https://prod-images-static.radiopaedia.org/images/4326561/0cfc9a4b4c0e4f3a8bb497e8e52ec2_big_gallery.jpg","isStack":true,"diagnosticCertainty":"probable"},{"imageId":16055898,"studyId":42201,"caseSlug":"orbital-pseudotumour-5","caption":"Case 3","thumbnail":"https://prod-images-static.radiopaedia.org/images/16055898/2305054b806526d55e4d797a77e773_big_gallery.jpeg","isStack":true,"diagnosticCertainty":"confirmed_substantiated"},{"imageId":28893245,"studyId":57293,"caseSlug":"orbital-pseudotumour-7","caption":"Case 4","thumbnail":"https://prod-images-static.radiopaedia.org/images/28893245/db77a60abd31a85be85321cb23ac880707892975e28c3e7ed31da67a348433ef_big_gallery.jpeg","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated"},{"imageId":32782977,"studyId":62188,"caseSlug":"orbital-pseudotumor-3","caption":"Case 5","thumbnail":"https://prod-images-static.radiopaedia.org/images/32782977/2f786776d8e2595dfcadb49e0e8b1b_big_gallery.jpeg","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated"},{"imageId":34060821,"studyId":63727,"caseSlug":"myositic-orbital-pseudotumour","caption":"Case 6: myositic pseudotumor","thumbnail":"https://prod-images-static.radiopaedia.org/images/34060821/dec9d0cc21a4bcf66cb154b3f42117_big_gallery.jpeg","isStack":true,"diagnosticCertainty":"confirmed_substantiated"},{"imageId":52956333,"studyId":92092,"caseSlug":"myositic-orbital-pseudotumour-inferior-rectus-muscle","caption":"Case 7","thumbnail":"https://prod-images-static.radiopaedia.org/images/52956333/acdabda29322e9f40152a36c557b6f_big_gallery.jpeg","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated"},{"imageId":48558773,"studyId":77433,"caseSlug":"orbital-pseudotumour-9","caption":"Case 8","thumbnail":"https://prod-images-static.radiopaedia.org/images/48558773/527ef2e75f05c08b71d342556e1c3b_big_gallery.jpeg","isStack":true,"diagnosticCertainty":"probable"},{"imageId":58666805,"studyId":121831,"caseSlug":"nonspecific-orbital-inflammation","caption":"Case 9: Idiopathic orbital inflammation","thumbnail":"https://prod-images-static.radiopaedia.org/images/58666805/23._big_gallery.jpeg","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated"},{"imageId":60925473,"studyId":131237,"caseSlug":"idiopathic-orbital-inflammation-3","caption":"Case 10","thumbnail":"https://prod-images-static.radiopaedia.org/images/60925473/7bae9c0a4ea20643a6c333d0c872ca920cd921eee8fe356a1407448dab3d719d_big_gallery.jpeg","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated"}],"ddx_inclusions":[{"imageId":13273,"studyId":6760,"caseSlug":"orbital-metastases-breast-cancer-1","caption":"Breast cancer metastases","thumbnail":"https://prod-images-static.radiopaedia.org/images/13273/a45b250a517709b113785d1700a107_big_gallery.jpeg","isStack":false,"diagnosticCertainty":"confirmed_unsubstantiated"},{"imageId":6216,"studyId":6593,"caseSlug":"orbital-malignant-melanoma","caption":"Orbital melanoma","thumbnail":"https://prod-images-static.radiopaedia.org/images/6216/b71d3b12c0136b6ce147d0ab83ca86_big_gallery.jpeg","isStack":false,"diagnosticCertainty":"probable"},{"imageId":1092,"studyId":10055,"caseSlug":"thyroid-associated-orbitopathy-7","caption":"Thyroid eye disease","thumbnail":"https://prod-images-static.radiopaedia.org/images/1092/a652111d5c9c978f6d57987ce185d7_big_gallery.jpeg","isStack":false,"diagnosticCertainty":"confirmed_substantiated"},{"imageId":381548,"studyId":9878,"caseSlug":"orbital-lymphoma","caption":"Orbital lymphoma","thumbnail":"https://prod-images-static.radiopaedia.org/images/381548/3e745869f2897b405ffbcd822bd342_big_gallery.jpg","isStack":true,"diagnosticCertainty":"confirmed_unsubstantiated"}],"lang":"us"}