Orbital Tumors - Pseudotumor

• Definition
  • Idiopathic orbital inflammatory disease "pseudotumor" is a nonspecific inflammation involving {the} orbit. It is a hypocellular lymphoid lesion, often incompletely replacing {the} orbital fat, lacrimal gland and extraocular muscles in which mature lymphocytes, plasma cells, histiocytes are seen
• Demographics
  • Males and females are equally affected. Both children and adults could be afflicted by idiopathic inflammations. Most often in middle-aged adults, but also young children and elderly patient . In children, approximately one-third of cases are bilateral. Bilateral pseudotumor in adults is less common and should elicit evaluation for systemic vasculitis such as Wegener's granulomatosis or polyatertitisis nodosa) and lymphoma.
• Etiology
  • The etiology of idiopathic orbital inflammation is unknown. It is believed to be an orbital immune reaction, although no local autoantigens in {the} orbit have been identified. Possibilities include a blood-borne antigen or antibody localizing in {the} orbit, which has a rich vasculature.
• Signs and Symptoms
  • The clinical presentation is dominated by inflammatory signs and could be variable. The acute form of {the} disease is {the} most striking.
• Signs
  • proptosis (probably {the} most frequent cause of following thyroid)
  • restricted eye-movement
  • conjunctival vascular congestion and edema
  • eyelid erythema and swelling
  • impaired vision
  • decreased corneal sensitivity (CNV1)
  • elevated IOP
  • intraocular: retinal and choroidal striae, optic nerve hyperemia and swelling, uveitis, and exudative retinal detachment
• Symptoms
  • constitutional symptoms (especially in children)
  • painful ophthalmoplegia
  • acute or recurrent, orbital pain
  • double vision
• Work-up
  • History or prior episodes, orbital CT which shows thickened posterior sclera (or a ring of scleral thickening), orbital fat or lacrimal-gland involvement, thickening of {the} extraocular muscles. In cases of orbital pseudotumor, bone destruction is uncommon.
• Differential diagnosis
  • The differential diagnosis of orbital pseudotumor includes orbital cellulitis, ruptured dermoid cyst, vasculitis (Wegeners'), lymphangioma, lymphoid tumor, and, in children, rhabdomyosarcoma, metastatic neuroblastoma, and Ewing's sarcoma. In {the} myocitic subtype, one must also consider thyroid orbitopathy; of note, in thyroid disease, {the} onset is usually slower, and although asymmetrical, it is often bilateral. Also in {the} differential in patients with enlarged extraocular muscles are metastatic carcinoma, direct carotid cavernous fistula, spontaneous dural cavernous fistula, and systemic lupus erythematous
• Classification of Psuedotumors
  • Rootman and Nugent classified acute orbital pseudotumors according to their orbital location, and described five patterns: anterior, diffuse, apical, myositic, and lacrimal.
• Anterior
  • inflammation involving {the} globe and anterior orbit with pain, lid swelling, Ptosis ( Ptosis is sometimes referred to as Blepharoptosis. It refers to an eyelid which is droopy. This could cause a loss of vision, especially while reading, headaches, and eyebrow strain. Please click on {the} Ptosis page for more details), diplopia, uveitis, papillitis, optic neuropathy, and exudative retinal detachment. CT reveals diffuse anterior orbital inflammation, scleral and choroidal thickening.
• Diffuse
  • inflammation similar to anterior pseudotumor but are more severe. Patients could exhibit more severe papillitis, choroiditis, and optic neuropathy. CT reveals diffuse orbital involvement.
• Apical
  • patients with posterior pseudotumors present with less proptosis, pain, and visible inflammation, but with a tendency toward {the} early development of optic neuropathy. CT reveals inflammatory process in {the} orbital apex, possibly extending along {the} course of {the} extraocular muscles
• Myositic
  • patients have one or more inflamed extraocular muscles. They often complain of sudden onset of retrobulbar pain, worsened with movement.. CT reveals diffuse enlargement of {the} extraocular muscle, including {the} insertion; in contrast, patients with thyroid ophthalmopathy have enlarged muscles, but sparing {the} insertion
• Lacrimal
  • patients with posterior pseudotumors present with less proptosis, pain, and visible inflammation, but with a tendency toward {the} early development of optic neuropathy. CT reveals inflammatory process in {the} orbital apex, possibly extending along {the} course of {the} extraocular muscles
• Pathology
  • The histopathologic findings in pseudotumor are variable, depending on where {the} biopsy was taken and when in {the} course of {the} disease it was sampled.
  • Classically, it is composed of 1) an infiltrate including lymphocytes plasma cells, macrophages, eosinophils, and rarely neutrophils 2) follicular lymphoid hyperplasia within a loose fibrous stroma.
  • Tissue that is more fibrous is seen in chronic situations. Children could exhibit a heavy eosinophilic infiltrate
• Treatment
  • In numerous cases, treatment of orbital pseudotumor could be initiated without a preceding orbital biopsy. Initial therapy consists of systemic corticosteroids adjusted for {the} patient's weight; typically 60- 100 mg/day of prednisone per day. In general, acute cases respond more rapidly than chronic cases and bilateral cases could require a longer course than unilateral disease.
  • Additionally, topical Predforte (1% Q.I.D. ) eye drops could be used to treat anterior chamber reaction.
  • A biopsy (with touch prep) is performed, however, if there is no clinical improvement after treatment with systemic steroids. Once {the} diagnosis is confirmed, additionally modalities of therapy include orbital irradiation (low-dose supervoltage radiation in {the} range of 1000 to 2000 rad is given in divided doses over a 10- to 15-day course) (101)., cyclophosphamide, and rarely orbital decompression.