Endocrine Abstracts

Introduction: Multiple endocrine neoplasia syndrome type 1 (MEN1) associated thymic carcinoids (Th-NETs) are rare and have poor prognosis. Cushing syndrome (CS) caused by Th-NET in MEN1 syndrome is extremely rare.

Case report: We report a case of a 55-year-old man with CS at presentation due to ectopic ACTH production in MEN1 syndrome. Thirty years ago, this patient had total gastric resection due to Zollinger-Ellison’s syndrome and extirpation of two tumors of pancreas, when diagnosed with gastrinoma. Three years prior to the manifestation of CS, the patient was diagnosed with primary hyperparathyroidism (PHPT) and thus treated with parathyroidectomy, near-total cervical thymectomy and total thyroidectomy. Histological analysis revealed hyperplasia of parathyroid glands, papillary thyroid carcinoma and regular thymic morphology. Based on gastrinoma and PHPT, the patient was diagnosed with MEN1 syndrome and the germline mutation of MEN1 gene was detected. This time, the patient presented with weakness, weight loss and hypokalemia. MDCT of the thorax revealed the large mediastinal mass. Subsequently, the percutaneous biopsy of the tumor was done and the histopathological analysis revealed neuroendocrine carcinoma. The tumor was operated and the diagnosis of atypical thymic carcinoid with high proliferative activity index Ki 67 was confirmed. Eight months after the operation control MDCT revealed recurrent mediastinal tumor that was reoperated. Three months after the reoperation the patient developed mediastinal lymphadenopathy.

Conclusion: The presented case of MEN1 is peculiar because the majority of Th-NETs in MEN1 are nonfunctional and ectopic secretion of ACTH seldom occurs. Although Th-NET did not show immunohistochemical staining for ACTH, level of ACTH in the blood significantly decreased after the operation. Therefore, it is not impossible that the carcinoid tumor may secrete ACTH precursors and/or CRH instead of ACTH. The present case highlights the importance of screening MEN1 patients for thymic carcinoid and reinforce the notion that subtotal transcervical thymectomy was not effective profilactic tool in this case.