bubble_chart Overview

Orbital pseudotumor is a relatively common orbital disease, ranking third among primary orbital tumors. It can occur at different ages, with a higher incidence in men, and is essentially a chronic non-specific inflammation. It is named for its ability to cause symptoms such as proptosis and impaired eye movement, which are characteristic of orbital tumors. Therefore, it needs to be differentiated from orbital tumors. Orbital pseudotumor is a non-specific chronic proliferative inflammation, not a tumor.

bubble_chart Epidemiology

This tumor is more common in males than in females, and the majority of patients are middle-aged or older.

bubble_chart Etiology

Pathologically, it includes the following 6 types:

1. Lymphocytic inflammatory pseudotumor: mainly characterized by a large number of lymphocytes reappearing; without tumor cells.

2. Plasma cell type inflammatory pseudotumor: mainly characterized by plasma cell proliferation.

3. Orbital myositis type: characterized by muscle hypertrophy accompanied by inflammatory cell proliferation.

4. Chronic granulomatous type: orbital fat necrosis accompanied by a large amount of granulation tissue proliferation.

5. Orbital vasculitis type: vasculitis accompanied by degenerative granulation tissue proliferation.

6. Sclerosing pseudotumor: characterized by a large amount of fibrous tissue proliferation, accompanied by collagen degeneration, and a small amount of inflammatory cell infiltration.

bubble_chart Clinical Manifestations

Protrusion of the eyeball is the main clinical symptom, mostly unilateral, with a few cases involving both sides. However, the onset in both eyes may occur sequentially. Some cases initially present with symptoms such as redness of the eye, abnormal eye movement, or diplopia at grade I. If this condition is more prominent or recurrent, it is easier to differentiate from true orbital tumors. In a few cases, after grade I protrusion of the eyeball, it may spontaneously retract, even leading to eyelid depression, severe impairment of eye movement, or fixation of the eyeball; most cases have a longer course, with continuous progression, and high protrusion of the eyeball may lead to exposure keratitis, affecting visual function or even causing blindness. In advanced stage cases, orbital X-rays may show an enlarged orbital cavity, even accompanied by bone absorption, but without bone destruction. If a very hard mass can be palpated at the orbital rim, along with significant pain and tenderness, it can be used to differentiate from orbital tumors (but caution is advised, and a biopsy should be performed if necessary). Since inflammatory adhesions mostly form at the orbital floor, such cases often show a downward and inward deviation, with restricted movement mainly in the upward and outward direction. A traction test can be used to explore the presence of adhesions within the orbit. The method involves applying a topical anesthetic, using a toothed forceps to grasp the tendon on the opposite side of the deviation, and pulling forcefully. If the deviation is caused by paralysis of the superior rectus muscle or a mass in the upper part, pulling upward can elevate the eyeball and reduce the degree of deviation; conversely, if the deviation is due to adhesions at the orbital floor, significant resistance will be felt when pulling the eyeball upward, and the degree of deviation will not decrease. This test can help differentiate between deviation caused by tissue adhesions and that caused by muscle paralysis or orbital tumors. This, to some extent, aids in the diagnosis of orbital pseudotumor.

In the early stages, this tumor disease mainly develops in the extraconal space of the orbit, and compression of the posterior pole of the eye is seen in very few cases, which distinguishes it from benign tumors originating within the muscle cone, such as hemangiomas, schwannomas, and meningiomas. In some cases, symptoms may significantly improve with the use of antibiotics and corticosteroids, so a therapeutic trial can also be conducted to assist in diagnosis and differential diagnosis. Difficult cases are easily confused with malignant orbital tumors. Early pathological examination should be performed to confirm the diagnosis.

bubble_chart Treatment Measures

For cases primarily involving lymphocyte proliferation, radiation therapy is applicable; for those mainly involving plasma cell proliferation, corticosteroids and antibiotics can be used; the orbital vasculitis type also responds well to corticosteroids. When high-degree exophthalmos leads to loss of membrane protection and drug therapy or radiotherapy is ineffective, surgical resection should be considered. However, caution is advised as surgery may trigger progressive irreversible edema, potentially extending the damage to the contralateral side. If necessary, cyclophosphamide and α-chymotrypsin can be added to the treatment regimen to enhance efficacy.