Orbital Pseudotumor:Idiopathic Orbital Inflammation

Shiva KambhampatiMS4,George Washington University School of Medicine/

University of North Carolina at Chapel Hill

Outline

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

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

Differential Diagnosis of Orbital Inflammation

Inflammatory Thyroid Opthalmopathy Sarcoidosis Wegener’s Orbital Cellulitis Abscess Vasculitis

Neoplastic Lymphoma Metastases

•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

Clinical Presentation

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

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

Case: Axial T1 Pre-Contrast

Axial T1 image shows isointense infiltrative process in left eye involving the retro-ocular fat and external rectus

muscle.

Case: Axial T2

Axial T2 image shows the process to be mostly hypointense. Note proptosis.

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.

Orbital Pseudotumor Forms

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

Differential Diagnosis of Orbital Inflammation Inflammatory

Thyroid Opthalmopathy Sarcoidosis Wegener’s Orbital Cellulitis Abscess Vasculitis

Neoplastic Lymphoma Metastases

Histology of Idiopathic Orbital Inflammation

Fibrous connective tissue and scant perivascular patchy polyclonal lymphocytic infiltrates

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

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

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

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

References Yuen SJ, Rubin PA. Idiopathic orbital inflammation: distribution,

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Lee et al. MR Imaging of Orbital Inflammatory Pseudotumors with Extraorbital Extension. Korean J Radiol. 2005 Apr-Jun; 6(2): 82–88.

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Weber AL, Romo LV, Sabates NR. Pseudotumor of the orbit. Clinical, pathologic, and radiologic evaluation. Radiol Clin North Am. 1999;37:151–168. [PubMed]

Maksimovic O, Bethge WA, Pintoffl JP et-al. Marginal zone B-cell non-Hodgkin's lymphoma of mucosa-associated lymphoid tissue type: imaging findings. AJR Am J Roentgenol. 2008;191 (3): 921-30. doi:10.2214/AJR.07.2629

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