A 60-year-old female smoker presented with bloody sputum and back pain. A computed tomographic (CT) scan of the chest revealed a mass lesion in S¹⁺² of the left lung and hilarmediastinal lymphadenopathy. TBLB revealed small cell carcinoma. At first, we thought that the patient's clinical staging was c-T4N2M0 IIIB disease. However, it was pointed out she had had hilar-mediastinal lymphadenopathy 7 years previously. Though FDG-PET revealed an increased uptake in the hilar-mediastinal lymph node, she was determined to have surgery. The resected specimen revealed the swollen lymph nodes to be sarcoidosis, accompanying a large cell neuroendocrine carcinoma (LCNEL). She was treated with a combination chemotherapy consisting of cisplatin and VP-16 and radiotherapy concurrently. Chest CT revealed a partial response of the primary site after 3 courses of chemoradiotherapy. Information on concomitant malignancies accompanying sarcoidosis is limited. Although the main types of concomitant malignancy are lung cancer, and lymphoma, there has been no description of LCNEC as a concomitant malignancy. In sarcoidosis patients, clinicians should be alert to the possibility of concomitant malignancy.