Orbital Inflammatory Disease

Non-infectious orbital inflammation encompasses a spectrum of conditions — from idiopathic pseudotumor to systemic autoimmune diseases — each requiring a distinct diagnostic and treatment approach.

Idiopathic Orbital Inflammation (Orbital Pseudotumor)

Idiopathic orbital inflammation (IOI), historically called orbital pseudotumor, is the most common cause of painful orbital disease in adults. It is a diagnosis of exclusion — a non-granulomatous, non-specific inflammatory process with no identifiable local or systemic cause. The acute form presents dramatically with rapid-onset periorbital pain, swelling, proptosis, and restricted eye movement. Bilateral involvement or a chronic, sclerosing pattern should prompt thorough investigation for systemic disease.

Subtypes by Anatomic Location

Dacryoadenitis

Lacrimal gland inflammation — S-shaped ptosis, tender swelling under the outer brow. Most common subtype.

Myositis

One or more extraocular muscles inflamed and enlarged. Painful eye movement, often mimics thyroid eye disease but muscles include the tendon.

Anterior (scleritis/perineuritis)

Affects the anterior orbit, sclera, or optic nerve sheath. May mimic orbital cellulitis.

Apical

Inflammation at the orbital apex. High risk of optic nerve compression and vision loss; requires urgent treatment.

Condition	First-Line	Second-Line	Refractory	Biopsy Role
IOI / Pseudotumor	Oral prednisone 1 mg/kg/day × 2–4 weeks then taper	Orbital radiation (20 Gy in 10 fractions)	Rituximab or methotrexate for steroid-dependent cases	If atypical features, no response to steroids within 48–72 h, or recurrence
IgG4-Related Orbital Disease	Oral glucocorticoids — usually prompt initial response	Rituximab (B-cell depletion) — preferred steroid-sparing agent	Azathioprine or mycophenolate mofetil	Required for definitive diagnosis: IgG4+ plasma cells > 10/HPF with storiform fibrosis
Sarcoidosis	Oral or periocular corticosteroids	Methotrexate — most widely used steroid-sparing agent	Infliximab for refractory cases	Tissue confirmation required; conjunctival or lacrimal gland biopsy often accessible
GPA (formerly Wegener's)	High-dose IV methylprednisolone + cyclophosphamide or rituximab	Rituximab now preferred over cyclophosphamide for induction	Azathioprine or methotrexate for maintenance	Tissue biopsy + c-ANCA (PR3-ANCA) positivity. Orbital biopsy often needed — sinus biopsy preferred when accessible

Orbital Inflammatory Disease

Idiopathic Orbital Inflammation (Orbital Pseudotumor)

Subtypes by Anatomic Location

IgG4-Related Orbital Disease

Clinical Features

Diagnostic Criteria

Systemic Inflammatory Conditions Affecting the Orbit

Orbital Sarcoidosis

Key Features

Granulomatosis with Polyangiitis (GPA)

Key Features

When Is Orbital Biopsy Required?

Indications for Biopsy

Treatment Comparison

Orbital Inflammation Care