The orbit is a bony cavity located in the skull where the eye and ocular adnexa reside. The eye is, therefore, not the only organ found in the orbit. On the contrary, there are numerous tissues in this space that are essential for visual function and protection of the eye. These tissues include blood vessels, nerves, fatty tissue, and the lacrimal gland. Abnormal growth of cells may arise from any of these tissues, creating a mass that will push the eye forward as it grows in this confined space. An orbital mass may be benign or cancerous, a distinction that must be made before choosing the best treatment.
How can we know if an orbital mass is benign or malignant?
Fortunately, benign orbital tumors behave very differently from orbital cancer. A benign mass is generally well-defined, not tender, and tends to grow slowly. Orbital cancer, on the other hand, is more aggressive in its clinical presentation. A malignant mass is poorly defined, produces
inflammation of the orbit, and usually grows quickly. Granted, these are only rules of thumb, and some benign masses may behave like malignant orbital tumors (see image).
For this reason, it is crucial to take a CT scan of the orbit when encountering an orbital mass. Clinicians may rely on specific radiologic signs to better discriminate between benign and malignant masses. Once the orbital surgeon has visualized the scan, he may decide to remove the mass entirely or take a biopsy.
Incisional vs. excisional biopsy of an orbital mass
When an orbital mass displays benign characteristics on the CT scan, surgeons may decide to remove it in its entirety in the operating room. Once removed, he will send it to the lab for pathological analysis. This process is called an excisional biopsy. Excisional biopsies should always be made when dealing with a benign lacrimal gland tumor. This is important because some benign tumors of the gland may become malignant if not removed early.
On the other hand, if a scan shows signs of malignancy, the tumor is very large, or there is much uncertainty about the type of tumor, orbital surgeons will want to take a sample of the mass and have it analyzed. This method is known as an incisional biopsy. Once a pathologist has provided a definite diagnosis, the best course of action can be determined, whether additional surgery is needed, or radiotherapy, chemotherapy, or a combination of these treatments is best.
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