Endocrine Abstracts

JOINT604

Ectopic adrenocorticotropic hormone secretion (EAS) remains one of the most difficult challenges in endocrinology, representing between 9 and 18% of ACTH-dependent Cushing`s syndrome (CS) cases. Thymic neuroendocrine tumors (NETTs) are rare, mostly aggressive tumors, that are responsible for about 5-16% of EAS in recent series. We present a unique case of 34-year old female with EAS caused by NETT - typical carcinoid. First disease manifestation occurred in April 2016, when patient presented with severe hypercortisolism, diagnosed as EAS. First-line cross-sectional imaging studies were inconclusive, only ⁶⁸Ga DOTA-TATE PET/CT revealed an oval lesion in the anterior mediastinum (1.9 x 1.3 cm) with subtle overexpression of somatostatin receptors (SUV max. 2.8). After initial treatment with steroid inhibitor (ketoconazole) the patient was sent to thoracoscopic removal of mediastinal tumor, in histopathological examination typical carcinoid without lymph node metastases was diagnosed. Postoperatively, transient adrenal insufficiency was observed with resolution of all symptoms. There was a diseases recurrence after 5 years of observation caused by a metastasis to the breast, shown in ⁶⁸Ga DOTA-TATE PET/CT and confirmed with breast biopsy. Again, treatment with steroid inhibitor (metyrapone) and tumor resection were curative. Last disease relapse appeared 7 years after initial treatment (January 2023), with severe hypercortisolism treated with osilodrostat. There was a local recurrence in the mediastinum and a thoracoscopic surgery was performed with good clinical and biochemical effect. The patients remains under a careful follow-up. In conclusion, our case proves that NETTs with EAS might present in young patients with well-differentiated tumor in histopathological examination and severe, life-threatening hypercortisolism despite small size of the primary lesion. ⁶⁸Ga-DOTATATE PET/CT is a very helpful tool to localize the tumor. There are only few descriptions of breast metastases from NETTs associated with EAS, our case was confirmed in biopsy and hormonally active. Finally, lifelong follow up should be performed despite complete remission after surgery.