DISCUSSION: ACTH secretion from thymic carcinoid is a very rare condition and has been described only in limited numbers (1). ACTH-dependent CS may result from ectopic ACTH production; and, it is usually difficult to distinguish from hypophyseal-ACTH secretion. Underlying slow growing tumor, such as carcinoids, can mimic Cushing's disease. Rarely can these tumors be cyclic secretuar and to carry out dynamic endocrine tests during this period is often inconclusive. Additionally, most of these tumors are occult and it is difficult to detect the source of ACTH production. In this case, higher plasma ACTH levels and no suppression were detected during low and high dose DST. IPSS was compatible with ectopic ACTH secretion and thorax CT revealed a thymic mass, as we considered ectopic ACTH syndrome due to thymic cancer, biopsy was performed and atypical carcinoid was detected. To confirm the ACTH source from this tissue, ACTH staining was performed and positive staining was detected. Treatment options of thymic carcinoids are surgical excision, chemotherapy, SRA (somatostatin receptors analogues) and radiotherapy. Due to aggressivity of the atypical carcinoid tumor, surgical cure can be achieved only in limited patients. Likewise, although different chemotherapy regimens are recommended, success rate is lower than 30%. As carcinoid tumors have expressed SRs, analogues can be used for suppression of tumor growth and ectopic hormone secretion (2,3). In our case, because of vascular invasion and multipl lympadenopathy, surgery was not preferred for initial therapy instead lanreotide, cisplatin and etoposide treatments were started and conventional radiotherapy was planned.