Orbital Pseudotumor Idiopathic Orbital Inflammation Shiva Kambhampati MS

Orbital Pseudotumor: Idiopathic Orbital Inflammation Shiva Kambhampati MS 4, 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 1900 s 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 3 rd most common cause of orbital inflammation

Differential Diagnosis of Orbital Inflammation Inflammatory Thyroid Opthalmopathy Sarcoidosis Wegener’s Orbital Cellulitis Abscess Vasculitis Neoplastic Lymphoma Metastases

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

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 T 1 Hypointense compared to normal muscle on T 2 Enhancement on post-contrast T 1 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 T 1 Pre-Contrast Axial T 1 image shows isointense infiltrative process in left eye involving the retro-ocular fat and external rectus muscle.

Case: Axial T 2 image shows the process to be mostly hypointense. Note proptosis.

Case: Axial T 1 Post-Contrast Post contrast T 1 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 Radiotherapy Usually rapid clinical response and resolution of pain 2 nd line therapy Adjuvant treatment when incomplete response 1 st line therapy if steroids contraindicated Immunomodulators/Immunosuppresants

Conclusions Fairly common cause of orbital inflammation (3 rd) 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 Ig. G 4 Related Systemic Disease Theory that links different inflammatory disorders that were previously thought to be unrelated

Ig. G 4 Related Systemic Disease (Ig. G 4 -RSD) Systemic disease that is characterized by extensive Ig. G 4 -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 Ig. G 4 -related The prototype is Ig. G 4 -related sclerosing pancreatitis (also known as autoimmune pancreatitis) Disease usually responds well to steroid therapy

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