A tumor is an abnormal growth of any tissue or structure; it can be either benign or malignant. Benign tumors often remain localized, while malignant tumors often spread into surrounding structures. A tumor can affect any part of the eye, such as the eye socket, eyeball, eye muscles, optic nerve, fat, and tissues. Sometimes tumors grow into the eye area, or tumors from other parts of the body travel to the eye. Most tumors of the eye are benign.
Basal cell carcinomas are the most frequently encountered kind of malignant tumor affecting the eyelid, making up 85% to 95% of all malignant eyelid tumors. The most common location is the inner portion of the lower eyelid, particularly in elderly, fair-skinned people. Prolonged exposure to sunlight seems to be a risk factor for developing this kind of tumor.
There are many different types of basal cell carcinomas, but the nodular variety is one of the most common. It appears as a raised, firm, pearly nodule with tiny dilated blood vessels. If the nodule is in the eyelash area, some lashes may be missing. The nodule may have some superficial ulceration and crusting and look like a chalazion or stye. Although these tumors are malignant, they rarely spread elsewhere in the body. For most of these tumors, surgery is the most effective treatment. In severe cases when the tumor has been neglected for a long time, it can spread into the eye socket, which may ultimately require removal of the eye and adjacent tissue.
Squamous cell carcinoma is the second most common kind of malignant eyelid tumor (occurring in approximately 5% of malignant eyelid tumors). As with basal cell carcinoma, the most common location is the lower eyelid, particularly in elderly, fair-skinned people. This tumor also appears as a raised nodule that can lead to loss of eyelashes in the involved area. When detected and treated early, the outcome for these tumors is excellent. However, if the tumor is neglected, it can spread to the lymph nodes in the neck. Surgery is the most effective treatment.
Sebaceous cell carcinoma originates in glands of the eyelid in elderly individuals. It is relatively rare but still accounts for 1% to 5% of malignant eyelid tumors. These are highly malignant tumors that may recur, invade the eye socket, or spread to lymph nodes. The tumor may look like a chalazion or stye, making it difficult to diagnose. Surgery is usually necessary for this kind of tumor.
Malignant melanoma makes up almost 1% of all malignant eyelid tumors but accounts for many of the deaths from malignant eyelid tumors. As with any other type of malignant melanoma, these tumors on the eyelid can arise from a pre-existing nevus or mole or may arise with no other pre-existing cause. Again, these tumors tend to occur in sun-exposed areas of elderly, fair-skinned people. Any areas of unusual or altered pigmented should be examined, especially if it is growing or changing color. Surgical removal is usually the recommended treatment.
The orbit is the bony socket that contains the eye, the muscles that move the eye, the optic nerve, and all the related nerves and blood vessels. The different kinds of orbital tumors include:
- optic nerve glioma, a benign tumor often associated with neurofibromatosis;
- orbital meningioma, a tumor growing from the tissue covering the brain;
- hemangioma, a benign tumor made up of blood vessels or vessel elements;
- lymphangioma, a tumor made up of enlarged lymphatic vessels;
- neurofibroma, a tumor made up nerve cells;
- sarcoma, a malignant tumor growing from connective tissue; and
- metastasis, a malignant tumor that spreads to the orbit from other parts of the body.
Signs of an orbital tumor include bulging of the eyeball, visual loss, double vision, or pain.
Once the tumor is discovered and imaged with magnetic resonance imaging (MRI) or computerized tomography (CT scan), it is usually necessary to perform a biopsy or remove the tumor in order to diagnose the tumor. If necessary, surgery is usually sufficient for most orbital tumors, including optic nerve glioma and meningioma. Some orbital tumors may require different or additional treatments. For malignant tumors including sarcomas and metastases, radiation therapy and sometimes chemotherapy are necessary.