Neuroendocrine tumor is a rare tumor originating from neuroendocrine cells. Although these tumors have the characteristics of the organ they originate from, they all show a common neuroendocrine structure. In neuroendocrine tumors of the lung, the location and aggressiveness of the tumor determine its clinical features. While recurrent infections, chest pain, cough, shortness of breath, pneumonia, and superior vena cava syndrome may develop in centrally located neuroendocrine tumors; peripherally located ones are usually detected incidentally. In this article, the diagnostic process and prognosis of the patient who developed vena cava superior syndrome due to lung neuroendocrine tumor is presented. A 59-year-old woman presented to us with complaints of swelling in the arm and shortness of breath for three weeks. In imaging examinations, conglomerate lymphadenopathy in the mediastinum, and lymphadenopathy that marked the vena cava superior in the right paratracheal region and extending into the vena cava were shown. Therefore, the patient was hospitalized with a preliminary diagnosis of vena cava superiorsyndrome. She was administered steroid and diuretic therapy. The biopsy shows high grade neuroendocrine tumor. Then, carboplatin-etoposide chemotherapy and radiotherapy were administered. The patient, who underwent significant regression in the imaging examination results, was exitus due to pulmonary embolism in the second month of treatment.