A tumor is an abnormal growth of any tissue or structure and can be either benign or malignant. Most tumors of the eye are benign.

Basal cell carcinoma is the most frequent type of malignant tumor to affect the eyelid (85-95% of all malignant eyelid tumors).  Prolonged exposure to sunlight seems to be a risk factor for developing this form of tumor.

The tumor 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.

Squamous cell carcinoma is the next most frequent malignant eyelid tumor (occurring in approximately 5% of malignant eyelid tumors.)  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 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 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.

Basal cell carcinoma		Squamous cell carcinoma