Pleomorphic Carcinoma with Exophthalmos and a Subsequent Diagnosis of Paraneoplastic Syndrome

The patient was a 75-year-old man who developed polyopia and exophthalmos. Chest computed tomography (CT) revealed a mass in the left upper lobe. A CT-guided biopsy suggested lung adenocarcinoma. He was treated by neoadjuvant chemotherapy followed by left upper lobectomy. He was diagnosed with stage IIB pleomorphic carcinoma postoperatively. Preoperative head magnetic resonance imaging revealed exophthalmos and bilateral swelling of the extraocular muscles. The thyroid function of the patient was within the normal range, and he tested negative for autoantibodies. As his symptoms and swelling of the extraocular muscles improved postoperatively, he was diagnosed with paraneoplastic syndrome.