Idiopathic orbital inflammation (IOI) is a benign inflammatory condition of the orbit with unknown cause. It presents with variable symptoms depending on location, such as eye pain, swelling, proptosis, and vision changes. Diagnosis is challenging and involves imaging like CT/MRI as well as biopsy. First line treatment is corticosteroids, though the condition remains difficult to manage.

1. IDIOPATHIC ORBITAL INFLAMMATION (IOI)
ADE WIJAYA, MD – FEBRUARY 2019

2. INTRODUCTION
 ~ orbital pseudotumor, nonspecific orbital inflammation, orbital inflammatory syndrome
 A benign, noninfective inflammatory condition of the orbit without any identifiable local or systemic
cause
 8%–10% of all orbital mass lesions
Shields JA, Shields CL, Scartozzi R. Survey of 1264 patients with orbital tumors and simulating lesions: The 2002 montgomery lecture, part 1. Ophthalmology. 2004;111:997–1008.
Wilson MW, Grossniklaus HE. Orbital disease in North America. Ophthalmol Clin North Am.1996;9:539–47.

3. Yeşiltaş YS, Gündüz AK. Idiopathic orbital inflammation: review of literature and new advances. Middle East African journal of ophthalmology. 2018 Apr;25(2):71.

4. CLINICAL FEATURES
 Acute – subacute – chronic
 Unilateral – bilateral in 8-20 %
 5th decade
 No sex predilection
 Orbital myositis most commonly affects young adults in the third to fourth decade of life and shows
female predilection
Swamy BN, McCluskey P, Nemet A, Crouch R, Martin P, Benger R, et al. Idiopathic orbital inflammatory syndrome: Clinical features and treatment outcomes. Br J Ophthalmol. 2007;91:1667–70.
Mombaerts I, Cameron JD, Chanlalit W, Garrity JA. Surgical debulking for idiopathic dacryoadenitis: A diagnosis and a cure. Ophthalmology. 2014;121:603–9.
Yan J, Wu P. Idiopathic orbital myositis. J Craniofac Surg. 2014;25:884–7.

5. ANTERIOR IOI
 Affects the globe, conjunctiva, eyelids, neural, and adjacent muscular structures
 Pain and periorbital swelling
 Conjunctival chemosis and limited ocular motility
 Rarely, proptosis, uveitis, papillitis, and exudative retinal detachment
Pakdaman MN, Sepahdari AR, Elkhamary SM. Orbital inflammatory disease: Pictorial review and differential diagnosis. World J Radiol. 2014;6:106–15.

6. DIFFUSE IOI
 Similar to anterior IOI but more severe
 Proptosis is more common
Pakdaman MN, Sepahdari AR, Elkhamary SM. Orbital inflammatory disease: Pictorial review and differential diagnosis. World J Radiol. 2014;6:106–15.

7. APICAL / POSTERIOR IOI
 Poorer visual outcome
 Orbital pain, restricted eye movement, visual loss, and minimal proptosis
Yuen SJ, Rubin PA. Idiopathic orbital inflammation: Distribution, clinical features, and treatment outcome.Arch Ophthalmol. 2003;121:491–9.
Ding ZX, Lip G, Chong V. Idiopathic orbital pseudotumour. Clin Radiol. 2011;66:886–92

8. ORBITAL MYOSITIS
 Unilateral orbital or periorbital pain, diplopia, ocular motility restriction, proptosis, eyelid swelling, and
conjunctival injection at the site of tendon insertion
 The most frequently involved muscle is the medial rectus followed by the superior, lateral and inferior
rectus muscles.
 Isolated levator palpebrae muscle involvement has also been seldom reported
Yuen SJ, Rubin PA. Idiopathic orbital inflammation: Distribution, clinical features, and treatment outcome.Arch Ophthalmol. 2003;121:491–9
Montagnese F, Wenninger S, Schoser B. “Orbiting around” the orbital myositis: Clinical features, differential diagnosis and therapy. J Neurol. 2016;263:631–40.
Almekhlafi MA, Fletcher WA. Levator palpebrae myositis. Neurology. 2008;71:1202

9. DACRYOADENITIS
 Most commonly encountered subtype of IOI (50 %)
 A painful, firm, erythematous mass with edema in the lateral upper eyelid, and S-shaped ptosis
sometimes associated with dry eye
 IgG-4 associated
 Can also affect the orbital soft tissue, optic nerve, trigeminal nerve branches, especially infraorbital nerve,
sclera, choroid, and orbital adnexa

10. PERISCLERITIS
 Periscleritis refers to inflammation involving the sclera, uvea, and/or Tenon's capsule.
 Clinical features of periscleritis include orbital pain, exophthalmos, eyelid edema, vision decrease, and
associated uveitis
Ding ZX, Lip G, Chong V. Idiopathic orbital pseudotumour. Clin Radiol. 2011;66:886–92.

11. OPTIC PERINEURITIS
 Optic perineuritis also known as perioptic neuritis, is a rare idiopathic orbital inflammatory disease, in
which the specific target tissue is the optic nerve sheath
 Optic perineuritis usually presents with pain, swollen optic disc, and arcuate and paracentral visual field
defects.
 Optic perineuritis usually responds well to systemic corticosteroids unlike the other entities in the
differential diagnosis
Purvin V, Kawasaki A, Jacobson DM. Optic perineuritis: Clinical and radiographic features. Arch Ophthalmol. 2001;119:1299–306.

12. FOCAL MASS IOI
 The clinical presentation varies according to the location and extent of the mass
Yeşiltaş YS, Gündüz AK. Idiopathic orbital inflammation: review of literature and new advances. Middle East African journal of ophthalmology. 2018 Apr;25(2):71.

13. SCLEROSING ORBITAL INFLAMMATION
 A small subset of IOI is associated with sclerosing orbital inflammation
 Severe, chronic, progressive disease often characterized by proptosis, mild inflammatory signs, restricted
ocular motility, and pain
 It may present as diffuse orbital involvement or with extraorbital involvement (intracranial or
infratemporal fossa)
 IgG-4 ROD
Zakir R, Manners RM, Ellison D, Barker S, Crick M. Idiopathic sclerosing inflammation of the orbit: A new finding of calcification. Br J Ophthalmol. 2000;84:1322–4.

14. PEDIATRIC IOI
 Uncommon
 Bilateral
 Constitutional signs and symptoms such as headache, fever, emesis, anorexia, lethargy, and abdominal
pain can be seen in up to 50% of the patients
 Optic disc edema, uveitis, and eosinophilia appear to be more common in the pediatric population
Spindle J, Tang SX, Davies B, Wladis EJ, Piozzi E, Pellegrini M, et al. Pediatric idiopathic orbital inflammation: Clinical features of 30 cases. Ophthalmic Plast Reconstr Surg. 2016;32:270–4.
Belanger C, Zhang KS, Reddy AK, Yen MT, Yen KG. Inflammatory disorders of the orbit in childhood: A case series. Am J Ophthalmol. 2010;150:460–3.

15. PATHOGENESIS
 Unknown
 Infectious process, autoimmune disorder, and aberrant wound healing
Alshaikh M, Kakakios AM, Kemp AS. Orbital myositis following streptococcal pharyngitis. J Paediatr Child Health. 2008;44:233–4.
Nieto JC, Kim N, Lucarelli MJ. Dacryoadenitis and orbital myositis associated with lyme disease. Arch Ophthalmol. 2008;126:1165–6.
Kawasaki A, Borruat FX. An unusual presentation of herpes zoster ophthalmicus: Orbital myositis preceding vesicular eruption. Am J Ophthalmol. 2003;136:574–5.

16. HISTOPATHOLOGY
 Chronic inflammatory infiltrate, composed mainly of small mature lymphocytes (predominantly T-cells),
plasma cells, neutrophils, eosinophils, and occasionally with histiocytes and macrophages
Mombaerts I, Goldschmeding R, Schlingemann RO, Koornneef L. What is orbital pseudotumor? Surv Ophthalmol. 1996;41:66–78.

17. DIAGNOSIS
 CT
 MRI
 Biopsy
Yeşiltaş YS, Gündüz AK. Idiopathic orbital inflammation: review of literature and new advances. Middle East African journal of ophthalmology. 2018 Apr;25(2):71.

18. TREATMENT
 Corticosteroids
 Nonsteroidal Anti-Inflammatory Drugs
 External Beam Radiotherapy
 Antimetabolites
 T-Cell/calcineurin Inhibitors
 Alkylating Agents
 Lymphocyte Inhibitors
 Tumor Necrosis Factor-α Inhibitors
 Surgery
 IVIg / PLEX

19. SUMMARY
 Diagnosis challenge
 Variable symptoms
 CT/MRI – Biopsy
 1st line therapy: corticosteroids