Orbital pseudotumor or idiopathic orbital inflammation is defined as a nonspecific inflammatory condition for which no identifiable cause or systemic disease can be found. It is a diagnosis made by exclusion, based on history, test results, clinical course, and response to treatment. We describe a child with bilateral orbital pseudotumor who presented with marked reduction of vision due to bilateral exudative retinal detachment.
A 15-year-old girl presented with bilateral painful loss of vision after a flu-like syndrome. She had been treated with systemic antibiotics by her local hospital without response. Her medical history was unremarkable.
On examination, the patient looked unwell with pyrexia of 38.60C. Visual acuity was reduced at 2/60 in the right eye and 1/60 in the left eye. There was bilateral proptosis, lid edema and erythema, limitation of extraocular movements, and conjunctival chemosis. Slit-lamp examination showed 2+ cells in the anterior chamber of both eyes. Fundus assessment showed 2+ cells in the vitreous, exudative retinal detachment, marked disk edema, tortuous retinal vessels, retinal striae, and scattered retinal hemorrhages (Fig. 1).
Laboratory studies included complete blood count, erythrocyte sedimentation rate, urea and electrolytes, liver function tests, serum angiotensin-converting enzyme, calcium, autoantibodies (including antinuclear antibodies, antineutrophil cytoplasmic antibodies, and rheumatoid factor), complement, thyroid function tests, antibodies against Borrelia and Toxoplasma, and blood cultures. Because the patient had recently emigrated from Africa, she was also tested for antibodies against human immunodeficiency virus types 1 and 2. Results of all of these tests were normal, other than an increased erythrocyte sedimentation rate of 99 mm/h and positive immunoglobulin G Toxoplasma antibodies. Findings on chest x-ray were normal.
Magnetic resonance imaging showed marked generalized bilateral uveoscleral thickening and soft tissue swelling of both orbits. There was edema of the tendinous part of the extraocular muscles and lacrimal glands. Intravenous gadolinium scan showed diffuse mild enhancement of the orbital inflammatory changes (Fig. 2). No intracranial abnormality was noted. These features were consistent with the diagnosis of orbital pseudotumor.
The patient was treated with 60 mg of prednisolone, which resulted in prompt improvement of the symptoms. Within 5 weeks, visual acuity improved to 6/9 in each eye, with resolution of the exudative retinal detachments. The steroid dose was tapered slowly. At 3 months, when the patient was receiving 15 mg of prednisolone, the inflammation relapsed. Visual acuity deteriorated to 6/36, and there was cellular activity in the anterior and posterior segments of both eyes. There was also residual edema of the left optic disk. The patient responded to an increase in the dose of prednisolone to 40 mg. During the next 3 months, the patient became steroid dependent, with relapse occurring whenever the dose of prednisolone was reduced to less than 20 mg. At that stage, azathioprine (100 mg/d) was added as a steroid-sparing agent. This resulted in control of the orbital inflammation and made it possible for the prednisolone dose to be reduced to 5 mg. The azathioprine dose was reduced to 50 mg/d when the patient had remained symptom free for 1 year. Six weeks later, the patient had another relapse that responded to an increase in the dose of both azathioprine and prednisolone. At 22 months of follow-up, die patient remains well, and visual acuity is 6/6 in both eyes. The patient takes a maintenance dose of 100 mg of azathioprine and 5 mg of prednisolone.
Orbital pseudotumor was first characterized as a distinct clinicopathologic entity in 1905 by BirchHirschfield, who described it as an orbital mass that simulated a neoplasm, but was histologically inflammatory.1 It consists of a broad range of orbital inflammatory diseases in the absence of a local or systemic identifiable cause, such as infection, neoplasm, or autoimmune disease. It is a space-occupying infiltrating orbital process that is characterized by abrupt onset of pain, proptosis, periocular erythema and edema, conjunctiva! chemosis, reduction of vision, and diplopia. Orbital inflammation may be diffuse or focal, targeting specific orbital tissues, such as the lacrimal gland, extraocular muscles, and orbital fat.2,3
Pediatrie orbital pseudotumors are rare and account for 6% to 16% of all orbital pseudotumors.2'4 In children, there is a higher incidence of bilateral involvement, uveitis, and disk swelling than in adults.3 On computed tomography, characteristics of orbital pseudotumor in 21 cases were enhancement with intravenous contrast medium (95%), infiltration of retrobulbar fat (76%), proptosis (71%), extraocular muscle involvement (57%), apical fat edema (48%), muscle tendon-sheath involvement (43%), optic nerve thickening (38%), uveal scierai thickening (33%), edema of the Tenon's capsule (3%), and lacrimal gland infiltration (5%).5'6 Our patient had posterior scleritis, documented by thickening of the sciera on magnetic resonance imaging, as well as inflammation of other orbital structures. Exudative retinal detachment is known to complicate cases of severe posterior scleritis and has been described in children.7 One could assume that the fundus findings in our patient - disk edema, tortuosity of vessels, exudative retinal detachment, and retinal hemorrhages - are secondary to the posterior scleritis. Bilateral serous detachment of the choroid and ciliary body with exudative retinal detachment is seen in uveal effusion syndrome, occurring especially in patients with nanophthalmic eyes. The pathophysiology of choroidal detachment in some patients with uveal effusion syndrome is abnormality of the sclera characterized by disorganization of collagen fiber bundles and deposits of proteoglycans in the matrix, leading to increased resistance to flow in the vortex veins.8
Enhancement after intravenous gadolinium, as seen in our patient, is a characteristic distinguishing between orbital pseudotumor and similar-appearing tumors (ie, lymphomas) that do not demonstrate significant enhancement.5 Another feature of orbital pseudotumor is diffuse enlargement of both the muscle and the tendinous part insertion to the globe, as seen in our patient. This is different from the fusiform enlargement with sharp borders seen in thyroid disease.5
The differential diagnosis of orbital pseudotumor in children is somewhat different from that in adults and includes orbital cellulitis, trauma, foreign body, dermoid and epidermoid cysts, capillary hemangioma, lymphangioma, dacryoadenitis, thyroid orbitopathy, and neoplasms, such as rhabdomyosarcoma, retinoblastoma, and neuroblastoma. Biopsy to exclude these diagnoses should be considered in children who do not respond to medical treatment and in those with atypical clinical presentation or radiologie findings.
Systemic steroid therapy has been established as first-line treatment for orbital pseudotumor.3'9'10 Although most patients respond well to this therapy, especially in the acute phase, a significant number of patients become either steroid dependent or steroid resistant. Steroid-induced side effects are also common and restricting for patients who are able to tolerate these agents.9 Recurrences have been described in up to 52% of patients. 3,9,10 Most of the available evidence about alternatives to steroids refers to the adult population, whereas there is limited information about other treatment options in children. In adults, immunomodulatory agents, such as cyclophosphamide and methotrexate, have been effective in controlling the inflammation.3·11 Our patient became steroid dependent and required the introduction of a steroid-sparing agent. She responded favorably to azathioprine, which she tolerated well. Because little is known about the recommended duration of immunomodulatory therapy in a child with orbital pseudotumor, we reduced the dose of azathioprine to 50 mg/d when the patient had been in remission for 1 year. The relapse of clinical signs and symptoms soon afterward indicates that longer treatment is required in these patients.
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