Eyelid tumors are not uncommon and can be benign or malignant. The most common malignant eyelid tumors include basal cell carcinoma, sebaceous gland carcinoma, squamous cell carcinoma, and malignant melanoma. The diagnosis of an eyelid tumor is best made on clinical examination by a specialist experienced with eyelid cancers and tumors. A complete blood profile and physical examine is recommended to evaluate the patient and other possible concerns. When the patient is taken to surgery for removal of the tumor, a histopathologist can review the specimen and formulate a diagnostic report. In some cases, tumors can be benign, and still cause discomfort or abnormal eyelid function. If you notice your pet has any lumpy bumps, it is always best to have them evaluated.