Ectopic Cushing’s syndrome due to adrenocorticotropic hormone secreting atypical thymic carcinoid tumor

Abstract

Cushing’s syndromes (CS) due to thymic carcinoids are rarely seen. In this text, a case with CS due to ectopic adrenocorticotropic hormone (ACTH) secreting atypical thymic carcinoid tumor is presented. A 50-year-old Turkish male patient wasadmitted to our emergency department with typical CS features. Basal hormone profile, low- and high-dose dexamethasonesuppression tests, and inferior petrosal sinus sampling results were consistent with ectopic ACTH secretion. Thorax computerized tomography showed an upper mediastinal mass, and trans-thoracic biopsy showed atypical thymic carcinoid with positiveACTH staining. Since the vascular invasion was detected, tumor was accepted inoperable; somatostatine receptor analogs,chemotherapy, and radiotherapy were planned. Ectopic CS can be derived from atypical thymic carcinoid. In this case, ACTHstaining was used to confirm ACTH secretion from thymic tissue, and positive staining was detected. ACTH staining routinelywas not performed for extra hypophyseal tissue tumors. In suspicious and difficult cases, ACTH staining can be helpful toconfirm the presence of ACTH in tumor tissues.