Orbital Pseudotumor: Idiopathic Orbital Inflammation Shiva Kambhampati MS4,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 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 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, clinical features, and treatment outcome. Arch Ophthalmol 2003;121:491-9. Lee et al. MR Imaging of Orbital Inflammatory Pseudotumors with Extraorbital Extension. Korean J Radiol. 2005 Apr-Jun; 6(2): 82–88. 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. 1993;14:181– 184.[PubMed] 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 Cheuk W. IgG4-related sclerosing disease: a critical appraisal of an evolving clinicopathologic entity. Advances in Anatomic Pathology. 2010 Sep;17(5):303-32.
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