A 78-year-old female with a previous history of endometrial lymphoma was referred to our hospital for F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) imaging on account of a growing tumor mass in the left eyeball with gradual visual loss for 5 months. The F-18 FDG PET/CT images showed a focal lesion with intense FDG uptake in the left bulbar conjunctiva with intraocular invasion. Excisional biopsy was performed under the impression of a malignant neoplasm, and the pathologic diagnosis confirmed squamous cell carcinoma.