Orbital Pseudotumor: Idiopathic Orbital Inflammation

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Orbital PseudotumorIdiopathic Orbital
Inflammation

• Shiva Kambhampati
• MS4,George Washington University School of
  Medicine/ University of North Carolina at Chapel
  Hill

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Outline

• What is Orbital Pseudotumor?
• Differential Diagnosis
• Case Presentation
• Radiological Findings and Analysis
• Orbital Pseudotumor Subtypes
• Treatment
• Conclusions

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What is Orbital Pseudotumor?

• First described in the 1900s
• AKA Idiopathic Orbital Inflammation, or
  nonspecific Orbital Inflammatory Disease
• Nonmalignant space occupying lesion involves
  orbital tissue and simulates a neoplasm
• Diagnosis of exclusion, based on patient
  history, clinical picture, response to steroids,
  and occasionally by biopsy
• Etiology unknown
• 3rd most common cause of orbital inflammation

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Differential Diagnosis of Orbital Inflammation

• Inflammatory
• Thyroid Opthalmopathy
• Sarcoidosis
• Wegeners
• Orbital Cellulitis
• Abscess
• Vasculitis
• Neoplastic
• Lymphoma
• Metastases

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Clinical Presentation

• Typically acute but can be insidious
• Painful
• Usually unilateral
• No real pattern of muscle involvement
• Ocular findings include
• Diplopia
• Decreased Visual Acuity
• Proptosis
• Edema
• Absent systemic symptoms

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Imaging Findings of Orbital Pseudotumor

• Imaging findings are characterized by
  inflammatory changes in orbital structures such
  as globe, lacrimal glands, extraocular muscles,
  orbital fat, and the optic nerve.
• MR findings
• Isointense on T1
• Hypointense compared to normal muscle on T2
• Enhancement on post-contrast T1 images

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Case Presentation

• 62 y-o male dull ache in left eye and limited EOM
• PMH uveitis
• Other Classical Clinical Presentations include
• Eye pain
• Edema
• Proptosis
• Motility Restriction
• Ophthalmoplegia
• Lid Erythema

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Case Axial T1 Pre-Contrast
Axial T1 image shows isointense infiltrative
process in left eye involving the retro-ocular
fat and external rectus muscle.
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Case Axial T2
Axial T2 image shows the process to be mostly
hypointense. Note proptosis.
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Case Axial T1 Post-Contrast
Post contrast T1 image shows the process to
enhance and extend to ipsilateral cavernous sinus
and along dura of left middle cranial fossa.
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Orbital Pseudotumor Forms

• Dacryoadenitis
• Myositis
• Sclerosis
• Optic Nerve involvement
• Tolosa-Hunt Syndrome
• Intracranial extension

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Differential Diagnosis of Orbital Inflammation

• Inflammatory
• Thyroid Opthalmopathy
• Sarcoidosis
• Wegeners
• Orbital Cellulitis
• Abscess
• Vasculitis
• Neoplastic
• Lymphoma
• Metastases

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Histology of Idiopathic Orbital Inflammation

• Fibrous connective tissue and scant perivascular
  patchy polyclonal lymphocytic infiltrates

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Treatment

• Systemic Corticosteroids
• Usually rapid clinical response and resolution of
  pain
• Radiotherapy
• 2nd line therapy
• Adjuvant treatment when incomplete response
• 1st line therapy if steroids contraindicated
• Immunomodulators/Immunosuppresants

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Conclusions

• Fairly common cause of orbital inflammation (3rd)
• Diagnosis of Exclusion, other causes must be
  ruled out
• Occasionally diagnosis by biopsy is performed
• Systemic Corticosteroids is primary treatment
• Rapid response to steroid treatment supports
  diagnosis of Orbital Pseudotumor
• MRI better imaging modality for characterizing
  intracranial extension
• Orbital Pseudotumor is not a lymphoid tumor

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Etiology

• Etiology of Idiopathic Orbital Pseudotumor is
  unknown, but there are some theories in the
  literature
• Originally it was thought to be infectious in
  origin, with historical reports occurring after
  viral illnesses.
• Autoimmune pathogenesis was theorized because of
  a strong association with and rheumatologic
  diseases.
• Reports of circulating antibodies against
  extraocular muscle proteins
• IgG4 Related Systemic Disease
• Theory that links different inflammatory
  disorders that were previously thought to be
  unrelated

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IgG4 Related Systemic Disease (IgG4-RSD)

• Systemic disease that is characterized by
  extensive IgG4-positive plasma cells and
  T-lymphocyte infiltration of various organs
• Pancreatitis, sclerosing cholangitis,
  cholecystitis, sialadenitis, retroperitoneal
  fibrosis, tubulointerstitial nephritis,
  interstitial pneumonia, prostatitis, inflammatory
  pseudotumor and lymphadenopathy, are all thought
  to be IgG4-related
• The prototype is IgG4-related sclerosing
  pancreatitis (also known as autoimmune
  pancreatitis)
• Disease usually responds well to steroid therapy

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References

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  inflammation distribution, clinical features,
  and treatment outcome. Arch Ophthalmol
  2003121491-9.
• Lee et al. MR Imaging of Orbital Inflammatory
  Pseudotumors with Extraorbital Extension. Korean
  J Radiol. 2005 Apr-Jun 6(2) 8288.
• Bencherif B, Zouaoui A, Chedid G, Kujas M, Van
  Effenterre R, Marsault C. Intracranial extension
  of an idiopathic orbital inflammatory
  pseudotumor. AJNR Am J Neuroradiol. 19931418118
  4.PubMed
• Weber AL, Romo LV, Sabates NR. Pseudotumor of the
  orbit. Clinical, pathologic, and radiologic
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