Ectopic ACTH Syndrome Caused By Thymic Neuroendocrine Tumor:a Case Report And Literature Review

Objective:To investigate the etiology,clinical manifestation,laboratory test,imaging features,diagnosis,treatment and prognosis of ectopic ACTH syndrome(EAS).Methods:Report one case of ectopic ACTH syndrome caused by thymic neuroendocrine tumor,review the relevant literature,summarize the etiology,clinical manifestations,laboratory examination,imaging features,diagnosis,treatment and prognosis of EAS.Result:A 36‐year‐old woman,initiallypresenting as reduced the volume of menstrual,was found to have typical Cushingoid features gradually.Her endocrine data showed that 24 h urine free cortisol(UFC)was positive,low dose dexamethasone suppression test(2‐days,2 mg)and high‐dose dexamethasone suppression test were not suppressed,a concentration ofplasma ACTH was elevated(>20 pg/mL).Computed tomography(CT)scan of the chest revealed alarge mass(12.8cm X8.4cm)in the anterior mediastinum.Magnetic resonance imaging of the pituitary showed no mass lesion.The appearance of the adrenals on CT scanning was normal.Thoracic surgery was performed in the local hospitaland the histopathological diagnosiswas thymoma B1.Thetypical Cushingoid features improved and the concentration of plasma ACTH and cortisol decreased after surgery.Symptoms of Cushing syndrome recurred 5 months after the operation,laboratory and imaging examination suggested multiple metastases.The surgical specimens were diagnosed as thymic neuroendocrine tumor by the department of pathology in our hospital.Positron emission tomography showedmultiple bone and lymph node metastases.The pathology of metastatic biopsy was consistent with neuroendocrine tumor(stage G3).The symptoms were improved after the treatment of blood pressure and blood glucosecontrol,as well as mifepristone antagonizing glucocorticoid receptor.And the chemotherapy regimen of etoposide and cisplatin was recommended.After discharge,the chemotherapy regimen of etoposidewas given at the local hospital,as well as the treatment of mifepristone to antagonize glucocorticoid receptors,controlling blood pressure and blood glucose,etc.Her symptomsrelief at the 4 months of followed up.Conclusion:Both neuroendocrine tumors and non‐endocrine tumors may be related to ectopic ACTH syndrome,and the most commonectopic ACTH‐producing tumors are thoracic(bronchial andthymic)and gastroenteropancreatic neuroendocrine tumors(NET).The clinical manifestations are often similar in ACTH‐dependent Cushing’s syndrome,but rapid onset and progression suggest the possibility of ectopic ACTH syndrome.Due to the lack of completely reliable diagnostic test procedure and imaging,it is necessary to combine clinical manifestations,laboratory tests,imaging tests and endocrine dynamic tests for comprehensive judgment,and sometimes multidisciplinary cooperation in diagnosis and treatment is required.Complete surgical resection of the primary tumor is the best treatment for the ectopic ACTH syndrome.Bilateraladrenalectomy and a variety of medications are options for the control of hypercortisolaemia.The prognosis of ectopic ACTH syndrome is related to the histological type of the tumor and the severity of hypercortisolemia.If the primary tumor cannot be completely cured,it is particularly important to controlhypercortisolemia and prevent its complications.