A 66-year-old female with a history of sinusitis presented with persistent diplopia and worsening eyelid swelling. Examination revealed bilateral vision loss, cranial nerve palsies, left-sided chemosis, proptosis, and edema. Initial imaging showed sphenoid sinus opacification, bilateral ethmoid disease, lack of filling of bilateral cavernous sinuses, and partial thrombosis of the left superior ophthalmic vein. The sinus findings were evaluated with endoscopic sinus surgery, which was unremarkable. Subsequent orbital imaging suggested the lesions were in keeping with tumor thrombus as opposed to bland thrombus. CT scans revealed a large mass in the right axilla, which was biopsied and confirmed the diagnosis of diffuse large B-cell lymphoma (DLBCL). The patient was treated with anticoagulation, steroids, and chemotherapy resulting in marked improvement. Our report highlights a rare case of tumor thrombus from DLBCL causing bilateral cavernous sinus thrombosis and, to the best of our knowledge, the first documented case of superior ophthalmic vein thrombosis from tumor thrombus.