Endocrine Abstracts

Introduction: Ectopic ACTH syndrome (EAS) is a rare cause of Cushing’s syndrome. EAS is most frequently caused by bronchial carcinoid tumor or small cell lung cancer. Medullary thyroid carcinoma (MTC) is a rare source of EAS, as reported in this case.

Case report: A 65-years-old-female with back pain and weight gain referred to our outpatient clinic with determined signs and symptoms of hypercortisolism. She had arterial hypertension, her sister had operated for thyroid malignancy. The significant findings were; centripedal obesity, plethora, muscle weakness, hypertension, overt diabetes and osteopenia. Laboratory tests were as follows: repeated 24-hour urinary free cortisol (UFC) excretions:900 and 978 μg/dl (n 36–137 /24h); midnight salivary cortisol:1.82 and 2.71 μg/dl (n <0.2 μg/dl); midnight plasma cortisol: 17.73 and 27.24 μg/dl (n <7,5 μg/dl), 1 mg dexamethasone supression test (DST): 17.56 μg/dl, 2 day 2 mg DST: 13.2 μg/dl.The high levels of ACTH (86.5 and 84.1 pg/ml), non-supressed 8 mg DST (18.03 μg/dl), insufficient increase serum cortisol and ACTH levels post CRH-stimulating testing and no mass on pitutiary MRI scanning confirmed ectopic ACTH syndrome. Imaging studies performed for tumor localization, showed a solid thyroid nodule, 20×18 mm in diameter. Fine needle aspiration(FNA) of the thyroid nodule revealed MTC and calcitonin level in wash-out fluid from FNA was very high (12311 pg/ml), similar with plasma level (3068 pg/ml). Functional PET imaging with 68-Ga DOTATATE demonstrated pathological uptake at right thyroid lobe and right parapharyngeal area. A total thyroidectomy and bilateral, central neck dissection were performed, histology confirming MTC with immunohistochemistry-staining positive for calcitonin, CEA and ACTH. The carcinoma metastases were detected at lymph nodes localized at right level 2 and right parapharyngeal area. Postoperative 24-h UFC (368 μg/dl), 1 mg DST (4.8 μg/dl) and plasma ACTH (40.1 pg/ml) levels revealed uncontrolled hypercortisolism. The measurements of serum calcitonin and CEA were planned three months after surgery to detect the presence of residual disease.

Conclusion: Nearly 50 cases have been reported about EAS induced by MTC; however, to the best of our knowledge this is the first case in the literature from Turkey. Mortality in MTC with EAS due to complications of hypercortisolism is 50%. Therefore, management of Cushing’s syndrome in MTC is very important. Surgical removal of MTC is recommended to control CS, but management is limited to debulking metastatic disease.