The orbit is defined by the anatomic site that contains the bones of the eye socket, the eyeball, the muscles responsible for eye movement, the optic nerve and the fat which fills the spaces in between. Any of these structures may degenerate into a tumor. In addition, tumors arising from the surrounding sinuses, brain and nasal cavity may grow through bone and invade the orbital confines. Metastatic tumors may also travel to the orbit. Orbital tumors may affect both adults and children. Fortunately, in both age groups most orbital tumors are benign.
In children most tumors are the result of developmental abnormalities. The most common benign tumors in children are dermoids (cysts of the lining of bone) and hemangiomas (a blood vessel tumor). Children also commonly suffer from orbital cellulitis, an infection that usually starts as a severe sinusitis secondarily invades the orbit and results in prominence of the eyeball. Malignancies in childhood are unusual (most common is rhabdomyosarcoma), but any rapidly growing mass is cause for concern.
In the adult population the most common benign tumor is also a blood vessel tumor (hemangioma, lymphangioma and arteriovenous malformation). Tumors of the nerves (schwannoma), fat (lipoma), as well as those that evolve from the surrounding sinuses (mucocele) occur less commonly. Frequently pain and prominence of the eyes can be mistakenly attributed to the growth of a tumor. However, further evaluation often reveals a benign non-infectious inflammatory process termed pseudotumor (as an indication of the diagnostic confusion associated with this entity). Alternatively the inflammation may result from a systemic process such as Graves thyroid disease. The most common malignant orbital tumors in adults are lymphomas. Often they are initially confined to the orbit without any systemic manifestations. Metastatic tumors most frequently arise from the breast and prostate. Direct invasion of the orbit from the surrounding skin and sinus cavities can occur from squamous and basal cell cancer. Other malignancies that arise from tissues within the orbit are least common (hemangiopericytoma, chondrosarcoma, malignant neurofibroma).
The evaluation of a patient with a prominent eye begins with a careful history and examination by a specialist trained in the field of orbital diseases. In addition to progressive prominence of one or both eyes, troubling symptoms include pain, loss of vision or double vision, redness and swelling of the eyelids and the presence of a palpable mass. Most often either a CAT scan or MRI will be ordered to more carefully define the condition. If suspicious, a diagnostic biopsy may be required. Some conditions require no treatment. Others are best treated medically or with the use of radiation therapy. The remainder require surgical excision. Fortunately, surgery has become safer through the use of CAT scans and MRI for preoperative planning and the intraoperative use of operating microscopes and surgical lasers.
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