This weeks' clinical case presents a case where our initial diagnosis on clinical findings took a surprising turn once further investigations were underway.

A 61 year old woman presents with worsening redness and swelling of the right eye. The patient had been initially treated for viral and bacterial conjunctivitis in the past 4 weeks with no resolution. She had slow progression of symptoms. She started to experience double vision on lateral gaze and was referred to our clinic. At that time her vision was 20/20 without an afferent pupillary defect or pupil asymmetry. The patient did have a complete ptosis of the affected side as well with poor levator function but no pain.

Primary Gaze

Abduction

Elevation

There was +3 injection on the conjunctiva with a clear cornea. There were no signs of inflammation in the anterior chamber and the patient had a normal dilated fungus exam.

The patient was ordered imaging which revealed a right lateral large mass in the area of the lacrimal gland (red). There was no bone erosion that was seen.

A biopsy was performed suspecting cancer of the lacrimal gland such as adenocarcinoma, lymphoma or metastasis. To the surprise of the team, the biopsy came back positive for orbital pseudo tumor. The pathology reveal mixed inflammatory cells without signs of cancer or infection. The patient was started on oral steroids immediately for treatment of her condition.

Orbital Pseudotumor

Orbital Pseudotumor goes by several names such as Nonspecific Orbital Inflammation or idiopathic orbital inflammation. It is disease that is characterized by diffuse or localized inflammation of the eye, eye muscle, lacrimal gland, orbit, cavernous sinus (Tolosa Hunt). When it is diffuse it can affect the orbital fat as well.

Orbital Pseudotumor is the third most common orbital disease behind Thyroid Eye Disease and Orbital Lymphoma. The lacrimal gland is the most common area affected followed by extraocular muscles.

The pathophysiology of orbital pseudo tumor is clearly immune system related but there are multifactorial variables that have been associated with the disease. These include:

1. Previous infection

2. Crohn's disease

3. SLE

4. Ankylosing Spondylitis

5. Thyroid Eye Disease

6. Myasthenia Gravis

Presentation

Orbital Pseudotumor traditionally presents with pain, redness, swelling. Double vision in extraocular muscle involvement or decreased vision in optic nerve involvement can occur. Often Orbital Pseudotumor is initially misdiagnosed as preseptal cellulitis, orbital cellulitis or conjunctivitis. Often there is no sinus opacification that is seen in orbital cellulitis which can be helpful in differentiation. To add to the confusion, fever can also be seen in orbital pseudotumor just like orbital cellulitis.

Imaging

Cat Scan or MRI of the Orbits can be very helpful and shows diffuse enlargement or mass in the orbit.

Localization of disease can easily be identified with imaging in some cases

Enlarged muscles for Myositis in Orbital Pseudotumor

Optic Nerve Sheath Enhancement in Optic Nerve Involvement

Diffuse enhancement Sclera involved disease

Enhancement of Orbital Apex

Biopsy

A biopsy of the lesion is ideal however that may be difficult in orbital apex or cavernous sinus involvement. In those cases, a clinical diagnosis is made.

Treatment

Treatment in Orbital Pseudotumor is primarily steroids such as prednisone but radiation and immunomodulating agents are commonly used in recalcitrant cases such as Rituxan, Methotrexate etc. Surgery is rarely used in cases where a mass is not located in or around vital structures. Studies have shown approximately 2/3 of patients will have complete resolution of symptoms with therapy. 25% of patients respond poorly to treatment and may suffer with chronic disease.

These cases give us a good example of how clinical decision making should take a stepwise and organized format to prevent "rush to judgements" and that despite a wealth of clinical experience, there are surprises at every turn.