Idiopathic orbital inflammatory syndrome without pain: A case report

Article Outline

• Abstract
• Case
• Discussion
• Conclusion
• References
• Copyright

Abstract 

Background

Idiopathic orbital inflammatory syndrome (IOIS) is a collection of primary orbital inflammatory expressions manifested in a variety of clinical presentations. Because the process is idiopathic, it lacks association with neoplastic, infectious, or systemic immunologic and inflammatory diseases. Therefore, an extensive analysis is required to exclude secondary etiologies of orbital inflammation.

Case report

Exhibited is a case of a 68-year-old white man presenting with a recent history of viral conjunctivitis and acute complaints of monocular vision loss, epiphora, photophobia, and generalized irritation without pain. On examination, he was found to have chemosis, a serous retinal detachment, and choroidal detachments. Magnetic resonance imaging found evidence of dacryoadenitis, posterior scleritis, and mild diffuse orbital inflammation. Extensive history and physical examination found no evidence of systemic inflammatory disease. IOIS was diagnosed and treated successfully with prednisone, without recurrence.

Conclusions

Pain is historically considered a cardinal sign of acute inflammation and a predominant symptom of IOIS. The authors present a case of acute IOIS, atypical because of its presentation in the absence of pain. In addition, a review of the literature is conducted to identify predominant clinical and radiologic characteristics of IOIS along with current accepted and proposed treatment options. Differentials are discussed to distinguish this disease from systemic immunologic and inflammatory conditions such as syphilis, sarcoidosis, and Wegener's granulomatosis as well as potentially fatal neoplastic conditions.

Keywords: Idiopathic orbital inflammatory syndrome, Inflammatory orbital pseudotumor, Magnetic resonance imaging, Posterior scleritis, Serous retinal detachment

Idiopathic orbital inflammatory syndrome (IOIS) represents a constellation of inflammatory manifestations of the orbit in the absence of infectious, neoplastic, systemic fibro-inflammatory, granulomatous, or vasculitic disease. IOIS is a relatively rare disease, encompassing only 6% of all orbital lesions.¹ This pathology was initially termed inflammatory orbital pseudotumor in 1930 upon presentation of a primary orbital inflammatory lesion that was discovered during orbital exploration for an expected neoplasm.² The term orbital inflammatory pseudotumor has been replaced largely by IOIS to encompass orbital inflammatory manifestations that may present without space-occupying, masslike signs and symptoms.

IOIS presents as inflammation of any structure within the orbit, including the extraocular muscles and their tendons, lacrimal gland, sclera, orbital fibro-fatty matrix, and perineural connective tissue.¹, ³ Classifications of IOIS are based on anatomic involvement when it presents with localized or isolated manifestations. For example, when inflammation is localized to the orbital apex, superior orbital fissure, and anterior cavernous sinus (causing sudden severe pain around or behind one eye), it is termed Tolosa-Hunt syndrome. Examples of isolated anatomic classifications include myositis, dacryoadenitis, tenonitis, scleritis, trochleitis, and perioptic neuritis. IOIS may also be classified according to histopathologic type, including histopathologically classic (infiltrate containing lymphocytes, plasma cells, and histiocytes within the preserved but edematous architecture of the affected tissue), dominant sclerosis, granulomatous, vasculitic, and tissue eosinophilia.⁴

Because of the histopathologic and anatomic variations, IOIS may manifest a heterogenous assortment of clinical signs and symptoms. It almost always presents unilaterally, except in myositic cases.¹, ⁴ IOIS typically presents with pain, proptosis, periorbital edema, conjunctival injection, and chemosis. Although symptoms generally present in an acute fashion, they also may occur insidiously over a period of months.⁴ Extraocular muscle motility restrictions, ptosis, and vision loss from optic nerve compression or perineuritis of the optic nerve may also be observed.

Epidemiologic observations show that IOIS is most prevalent in the third to fifth decades of life, although it has been documented in infants and geriatric patients.¹, ⁵ IOIS has been reported to have no racial or sex predilection.¹ However, there is some variability in epidemiologic reports on sex, suggesting a predominance among women (1.8:1). This finding may be skewed because of a greater female predominance in the myositic and Tolosa-Hunt subsets.⁵, ⁶

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Case 

A 68-year-old white man presented to the eye clinic with complaints of reduced vision, photophobia, epiphora, and irritation of the right eye. He denied any pain. His medical history included non–insulin-dependent diabetes, hypertension, hypertriglyceridemia, cardiomyopathy, and atrial fibrillation. He also had previous radiologic evidence of a pulmonary granuloma, which resolved 1 year before his ocular symptoms presented. The etiology of this granuloma remains unknown. The patient had no other clinical evidence of systemic inflammatory disease. His ocular history was significant for early dry age-related macular degeneration (ARMD) and physiologically large cup-to-disc ratios. His history also included a recent episode of ocular redness and epiphora in the right eye (O.D.), which had been diagnosed as an acute viral conjunctivitis. He reported to our clinic because the course of this presumed viral conjunctivitis had worsened. Most notably, he had experienced a dramatic reduction in acuity. He denied photopsia, visual field defects, fever, sore throat, or malaise.

Corrected visual acuities were 20/200 O.D. and 20/20 in the left eye (O.S.), with no improvement on pinhole testing. Pupils were reactive with a 1+ afferent defect O.D., and extraocular motilities exhibited full range of motion without pain in both eyes (OU). Confrontation visual fields showed absolute constriction of the superior peripheral field, without respect for the midline. His paracentral visual field was normal to confrontation. Exophthalmometry showed that the right eye was slightly proptotic with measurements of 24 mm O.D. and 21 mm O.S. Anterior segment examination of the right eye found grade 3+ conjunctival chemosis, grade 3+ generalized conjunctival hyperemia, and grade 1+ superior and inferior palpebral follicles. The conjunctiva in left eye was clear, and the corneas were clear bilaterally. Intraocular pressures were 14 mmHg O.D. and 15 mmHg O.S. by Goldmann tonometry.

Dilated fundus examination of the right eye found an extensive serous retinal detachment extending from the peripheral retina in all quadrants through the posterior pole, including the fovea. Peripheral choroidal detachments were also present for 360° (see Figure 1). Retinal findings in the left eye included those associated with early ARMD, specifically mild mottling of the retinal pigment epithelium and rare small drusen. The patient received a tentative diagnosis of posterior scleritis O.D. Magnetic resonance imaging (MRI) of the brain and orbits, magnetic resonance angiography (MRA), and laboratory tests were ordered. The patient was started on 80 mg oral prednisone along with 20 mg of omeprazole, a consult with a retina specialist was submitted, and the patient was asked to return to the clinic the following day.

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• Figure 1 

  Fundus photographs. White arrows indicate serous retinal detachment. Yellow arrows indicate choroidal detachment.

The MRI study found significant edema of the right lacrimal gland and inflammation of the posterior sclera on the right side. There was also a generalized orbital inflammatory response indicated by retrobulbar contrast enhancement (see Figure 2). The ophthalmic vein was normal in caliber, and there was no evidence of orbital varix. The MRA study showed normal vascular anatomy without carotid cavernous fistula. A complete blood count with differentials found normal eosinophil and neutrophil counts, although there was a slightly elevated white blood cell (WBC) count to 12.23 K/cmm (normal WBC: 3.20 to 10.0 K/cmm for the laboratory used.) The mild leukocytosis was attributed to initiating oral prednisone on the day before blood was drawn. His Westergren erythrocyte sedimentation rate was age appropriately normal at 24 mm/h. Other tests ordered included complete blood chemistry panel, urinalysis, antinuclear antibodies, antineutrophil cytoplasmic antibodies, and purified protein derivative. Each of the laboratory results showed no indication of systemic inflammatory disease.

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• Figure 2 

  MRI showing the right eye's choroidal detachment, swollen lacrimal gland, and contrast enhancement of the posterior sclera with mild intraorbital diffusion of contrast. Green arrow indicates orbital portion and blue arrow indicates palpebral portion of the lacrimal gland.

A number of orbital conditions were considered for the etiology of this clinical presentation (see Table 1). A lack of pulsatile proptosis and bruit along with a normal MRA successfully ruled out carotid cavernous fistula. Normal cavernous sinuses on MRI and absence of fever and chills excluded cavernous sinus thrombosis. Orbital cellulitis was eliminated from the differentials because of the absence of fever and minimal leukocytosis with normal neutrophil count. Mucormycosis was not considered because the patient had no significant history of immunosuppression or acidosis and did not present with fever or pain. MRI demonstrated no evidence of orbital neoplasm or infection. The invariable nature of this patient's proptosis on Valsalva maneuver made venous varix unlikely, and the absence of such was proven by the magnetic resonance study. The laboratory results and imaging studies confirmed an inflammatory response involving the eye and orbit without evidence of infection, aberrant vascular changes, neoplastic disease, or other space-occupying lesions. Because the MRI showed lacrimal gland inflammation, scleritis, and retrobulbar extension of inflammation, posterior scleritis on the right side with disseminated orbital inflammation was diagnosed. Subsequently, systemic inflammatory disease etiologies and IOIS were then considered as diagnoses.

Table 1.

A detailed history, physical examination, and appropriate laboratory studies were conducted to evaluate for systemic conditions that may prompt orbital inflammation. Table 2 includes several systemic diseases that should be considered. Because of the patient's previous history of lung granulomas, it was important to rule out Wegener's granulomatosis, which can present with signs and symptoms similar to those in this case. Normal creatinine levels on serology and an absence of red blood cells on urinalysis confirmed the lack of glomerular nephritis, which, along with the absence of antineutrophil cytoplasmic antibodies, ruled out Wegener's granulomatosis. After excluding all evidence of systemic inflammatory and autoimmune disease processes, IOIS was diagnosed. His oral prednisone was continued for 10 days at 80 mg/d, with a slow taper over 5 months. The patient's symptoms and orbital signs resolved within 5 weeks, with the serous retinal detachments resolving in 3.5 months. Visual acuity in the affected eye returned to 20/25. The patient has subsequently been followed up for 19 months without recurrence.

Table 2. Disease mimickers of idiopathic orbital inflammatory syndrome

Disease processes	Examples
Infectious disease	Orbital cellulitis	Infectious dacryoadenitis
Neoplastic disease	Lymphoma/lymphoid tumors	Lacrimal gland cancers (ie, adenocarcinoma)
	Metastatic carcinoma	Plasmacytoma
	Orbital cavernoma	Meningioma
Vascular malformation	Venous varix	Cavernous sinus fistula
Systemic inflammatory and immunologic diseases	Wegener's granulomatosis	Polyarteritis nodosa
	Sarcoidosis	Thyroid eye disease
	Systemic lupus erythematosus	Sjögren's syndrome
	Rheumatoid arthritis

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Discussion 

The described case is a unique presentation of IOIS manifested as posterior scleritis with concomitant lacrimal gland and orbital fibro-fatty matrix inflammation in the absence of pain. Pain is often considered a cardinal characteristic of inflammation; however, it is not reported in all cases of IOIS. Pain was noted as the most predominant clinical feature (69%) in an evaluation of 90 eyes with IOIS by Ahn Yuen and Rubin.⁵ In a similar study evaluating the clinical features of 24 cases of IOIS, Swamy et al.⁷ only noted pain as a presenting symptom in 58% of patients. The lower incidence of pain in the latter retrospective study may be attributed to selection bias, because it was reported that three quarters of patients initially considered in this evaluation were excluded because a biopsy was not performed. This fact would potentially skew the data toward atypical cases because it is possible that a higher proportion of patients presenting with orbital inflammatory manifestations in the absence of pain would undergo a biopsy. Regardless, both of these studies indicate that a significant percentage of patients with IOIS report associated pain.

Idiopathic orbital inflammatory syndrome, by definition, is a diagnosis of exclusion. Although orbital inflammation may be observed in association with systemic disease, such manifestations are excluded from the primary process classified as IOIS. Therefore, the impetus in diagnosing IOIS is placed on first supporting a diagnosis of orbital inflammation, and second, ruling out any infectious, neoplastic, or systemic disease that can cause orbital inflammatory manifestations such as polyarteritis nodosa, Wegener's granulomatosis, syphilis, and sarcoidosis (see Table 2). Upon exclusion of associated infectious, neoplastic, or systemic inflammatory diseases, a primary idiopathic orbital inflammation can be deduced, and IOIS can then be conferred as a diagnosis.

A key component of the management of IOIS is the performance of appropriate radiologic studies. Magnetic resonance imaging is superior to computed tomography for analysis of soft tissue inflammation. Orbital inflammation most often presents with an MRI signal intensity that is isointense to muscle on T1-weighted imaging and isointense or minimally hyperintense to fat on T2-weighted imaging.⁸, ⁹ These characteristics are notable for the swollen lacrimal gland in Figure 2. Multiple cases have been presented showing extraorbital extension of these inflammatory signal characteristics.¹⁰, ¹¹ An additional characteristic of inflammation is that it typically will present slightly darker or unchanged on T2-weighted images relative to its appearance on T1-weighted images.¹² These findings distinguish inflammation from other pathologies, such as most varieties of neoplasms, which often present a relatively high T2-weighted signal. However, not all neoplasms share this characteristic. Meningiomas and lymphomas may often be indistinguishable from orbital inflammation because of their capacity to demonstrate T2-weighted isointense signals.⁹

Although no finding is pathognomonic for meningioma or lymphoma, some published discriminating radiologic features have been described as highly suggestive indicators for these pathologies. Meningiomas are classically described as having an extension into the dura or a “dural tail.” In addition, optic nerve meningiomas are most often described as having a characteristic “tram track” appearance of optic nerve sheath enhancement.¹⁴ This radiologic trait results from the circumferential thickening of the optic nerve sheath produced by meningiomas. On MRI, the contrast enhanced T1-weighted axial or sagittal image shows 2 enhanced rows of tumor separated by the relatively low signal optic nerve, creating the “tram track” attribute. To differentiate lymphoma from IOIS, Yan et al.¹² presented a retrospective review of 209 patients with IOIS and 110 patients with lymphoid tumors. Two discriminating MRI characteristics determined IOIS: (1) greater contrast enhancement than noted in lymphoid infiltration and (2) slightly darker or unchanged T2-weighted image relative to T1-weighted image. The T2-weighted signal presented slightly brighter than T1 for lymphomatous infiltrates.

Another diagnostic challenge is encountered when differentiating idiopathic perioptic neuritis, a rare subset of IOIS, from demyelinating optic neuritis. This is an important distinction because oral corticosteroid treatment has been shown to be an effective treatment for perineuritis, but has been shown to facilitate recurrence in optic neuritis.⁹ Purvin et al.¹³ reviewed 14 patients with perioptic neuritis to delineate its clinical characteristics relative to optic neuritis associated with demyelinating disease. They found that the average age of perioptic neuritis patients is older than those with optic neuritis; however, the age range is extensive and overlaps optic neuritis. In addition, perioptic neuritis patients tend to have sparing of central vision with paracentral or arcuate defects that progress over weeks compared with optic neuritis, which typically affects central vision and progresses over days with subsequent spontaneous recovery. In addition, treatment of perioptic neuritis with corticosteroids yields dramatic relief of pain, often within hours.¹³ Careful observation of the optic nerve on MRI of perineuritis will show enhancement around, rather than within, the optic nerve in the majority of cases, because the sheath is the focus of inflammation.⁹ This radiologic appearance is similar to the “tram track” sign of a meningioma, but often there will be mild evidence of other orbital inflammation concurrent with optic perineuritis, such as pathologic enhancement of an extraocular muscle or sclera, as well as streaky enhancement of orbital fat.¹³

Upon diagnostic confirmation of orbital inflammation, infectious, neoplastic, and systemic inflammatory disease must be ruled out. This mandates a thorough history and physical examination. Based on clinical signs and symptoms, this often entails an extensive hematologic evaluation to include complete blood count with differentials, erythrocyte sedimentation rate, antinuclear antibodies, anti–double-stranded DNA, antineutrophil cytoplasmic antibodies, angiotensin-converting enzyme level, fluorescent treponemal antibody absorbed test, rapid plasma reagin test, and serum protein electrophoresis.

In the adult population, the most common orbital inflammatory disease is thyroid-associated orbitopathy (TAO). This process represents an orbital expression of systemic disease, most often Graves' disease, and thus should be included as a possible differential diagnosis. Patients with TAO usually present with bilateral but often asymmetric orbital involvement and do not typically report pain. Differentiating clinical signs include tendon-sparing extraocular muscle enlargement, eyelid retraction, exophthalmos, and a hallmark characteristic lag in eyelid movement behind the associated movement of the globe during vertical ocular pursuits.¹⁵

Another important differential for IOIS includes neoplasm, which may present with a certain degree of inflammation. In this circumstance, the role of a biopsy is debatable. Some clinicians recommend biopsy on all cases presenting as orbital inflammation, except (1) in a young patient with painful ophthalmoplegia, ptosis, and mild proptosis along with an orbital radiologic pattern showing only myositis and (2) patients with orbital apex syndrome.⁸ Others are more conservative, reserving biopsy for patients whose inflammation does not respond abruptly to corticosteroid treatment, is refractory to steroid treatment, or is recurrent in nature.⁵, ⁹ This biopsy-conservative treatment plan has been perpetuated by a long-standing hypothesis that IOIS can be confirmed by its immediate and dramatic response to corticosteroids. Some clinicians have deemed this expected result to therefore be a therapeutic challenge test to substantiate this diagnosis. However, in a study evaluating this hypothesis, the results of such a response to corticosteroids are shown to have a sensitivity of only 78% and a false-positive rate of 11%.¹⁶, ¹⁷

Although spontaneous remission may occur without therapy for IOIS patients, clinicians often initiate 60 to 100 mg of corticosteroids daily for adults, followed by a slow taper over 4 to 6 weeks (see Table 3).¹⁸ Treatment with oral corticosteroids alone has been shown to be effective in 31% to 37% of patients.¹⁶, ¹⁸, ¹⁹ For cases of apical involvement and vision loss, intravenous corticosteroids should be considered.³, ¹⁶ Recurrence after initial response to corticosteroid treatment is estimated to be 52%,¹⁶ and in such cases, biopsy is recommended. This should then be followed by a second course of corticosteroids instituted over a longer treatment period with a prolonged tapering dosage.¹ Fibrotic and inflammatory mass lesions, often presenting similar to a tumor of the lacrimal gland, are the most resistant to corticosteroids.¹⁹ Recently, pilot study data were presented by Leibovitch et al.²⁰ showing the effectiveness of intraorbital triamcinolone injections for IOIS. Of the 10 patients studied, 8 experienced complete resolution, and 1 experienced substantial improvement.

Table 3. Treatment for IOIS

Type of case to be treated	Treatment
Most cases	Corticosteroids (60-100 mg per day or 1.0 to 1.5 mg/kg/d)
Apical involvement and vision loss	IV corticosteroids (methylprednisolone 1.0 g/d for 1 to 3 days)
Large sclerotic or discrete masses	Surgical resection/debulking (intraorbital triamcinolone may be useful during surgery)
Steroid-responsive cases in steroid-intolerant patients	Radiation may be useful
1) Steroid-nonresponsive cases, 2) Patients who cannot be weaned, 3) Patients who cannot tolerate steroid and fail radiation treatment	Immunosuppressants (typically left to the responsibility of a rheumatologist) •Antimetabolites (methotrexate, azathioprine, mycophenolate mofetil) •T-cell inhibitors (cyclosporine, tacrolimus) •Alkylating agents (cyclophosphamide, chlorambucil)

Multiple treatment modalities have been suggested and considered effective for patients who are intolerant to steroids or for those in whom the condition is resistant to steroid treatment. Surgical resection often is the most effective for sclerotic or discrete involvement, and radiation is effective for many nonfibrotic cases refractory to corticosteroids.⁹, ¹⁹ Immunosuppressive therapy also is included in the treatment protocol for cases that have proven to be nonresponsive to radiation and for those cases presenting with predominant vasculitis.¹, ³, ⁹, ¹⁷ These include cytotoxic agents, such as cyclophosphamide and corticosteroid-sparing immunosuppressants, such as methotrexate. Additional proposed adjuvant treatments include intravenous immunoglobulin, plasmapheresis, and biological treatments, such as antitumor necrosis factor alpha.¹⁸ Any corticosteroid-resistant cases should be managed in conjunction with a rheumatologist.

IOIS remains an enigmatic and debatable orbital disease because of the variable spectrum of its clinical presentation, response to treatment, and sequelae. Because of this variability, debate has arisen among ophthalmic professionals as to whether IOIS is a single disease process with patient-dependent variations or a collection of diverse pathogenic processes.

In response to this ambiguity, Harris presents a pathogenic explanation, hypothesizing IOIS as a process of chronic inflammation with multiple potential initiators.³ This theory describes the processing and presenting of antigens via macrophages to helper T-cells, initiating a cellular response. The result is a cloning of more helper T-cells and production of cytokines that serve to activate more macrophages and cause effector T-cells to multiply and lyse the antigen-bearing cells. The consequence is cellular damage and tissue injury. Harris further hypothesizes that the inflammatory process may be initiated at any point along the cascade, noting for example that bacterial endotoxins can cause inflammation by their direct action on macrophages and that bacterial antigens may directly activate B-cells. He adds that the granulomatous pattern may be encountered when intracellular antigens and organisms, such as viruses, are not fully digested by macrophages. The result is a proliferation and aggregation of activated macrophages, T-cells, and isolate in a granulomatous pattern. He also notes that tissue injury can lead to a second, autoimmune wave of inflammation. This occurs as the injury alters the antigenicity of self-proteins, causing them to be recognized as foreign. Additionally, structural similarities may be present between foreign antigens and the peptides of normal orbital tissues, causing T-cells or antibodies to target them in other autoimmune responses.

A general conclusion from this pathogenic construct is that primary inflammation can manifest with variable clinical and histopathologic characteristics. Additionally, this pathogenic theory addresses the concept that although IOIS is a diagnosis of exclusion without a correlated systemic inflammatory or autoimmune process, there certainly may be systemic disease associations to prompt this primary, orbital inflammatory disease. These include viral upper respiratory infection,²¹ streptococcal pharyngitis,²² and Lyme disease.²³

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Conclusion 

Idiopathic orbital inflammatory syndrome is a disease that encompasses a constellation of orbital inflammatory manifestations with varied clinical characteristics, histopathologies, and responses to treatment. The variability of clinical signs and symptoms may pose a diagnostic challenge to clinicians, as exemplified by the atypical lack of pain in the case presented here. IOIS is identified in the absence of infectious, neoplastic, or systemic inflammatory and autoimmune disease processes. Laboratory and radiologic studies can provide valuable differentiation of this primary orbital inflammation, with an MRI providing superior clinic analysis for such soft tissue involvement. Oral corticosteroids remain the mainstay of initial treatment; however, preliminary evidence of the efficacy of injectable orbital corticosteroids suggests future promise with this modality.

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