A tumor is an abnormal growth of any tissue or structure and can be either benign or malignant. 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 frequent type of malignant tumor to affect the eyelid (85-95% of all malignant eyelid tumors). The most frequent 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 form 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. While 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 eyesocket, which may ultimately require removal of the eye and adjacent tissue.

Squamous cell carcinoma is the next most frequent 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 this type of tumor 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 eyesocket, 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 type 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 pigmented area should be examined, especially if it is growing or changing color. Surgical removal is usually the recommended treatment.