Case report: Thymic neuroendocrine tumor with metastasis to the breast causing ectopic Cushing`s syndrome

Aleksandra Zdrojowy-Wełna ^1* Marek Bolanowski ¹ Joanna Syrycka ^1,2 Aleksandra Jawiarczyk-Przybyłowska ¹ Justyna Kuliczkowska-Płaksej ¹

• ¹ Wroclaw Medical University, Wrocław, Poland
• ² Affidea PET/CT Diagnostic Center, Wrocław, Poland

Ectopic adrenocorticotropic hormone secretion (EAS) is responsible for about 10-18% of Cushing`s syndrome cases. Thymic neuroendocrine tumors (NETs) comprise 5-16% of EAS, therefore they are very rare and the data about this particular tumors is scarce. We present a case of 34-year old female with rapid onset of severe hypercortisolism on April 2016. After initial treatment with steroid inhibitor (ketoconazole) and diagnostics including 68 Ga DOTA-TATE PET/CT it was shown to be caused by a small thymic NET. After successful surgery and resolution of all symptoms, there was a recurrence after 5 years of observation caused by a metastasis to the breast, shown in 68 Ga 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, 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.Our case stays in accordance with recent literature data, showing that patients with thymic NETs are younger than previously considered and that the severity of hypercortisolism does not correlate with the tumor size. The symptoms of EAS associated with thymic NET may develop rapidly and may be severe, as in our case. Nuclear medicine improves the effectiveness of the tumor search, which is crucial in the successful EAS therapy. Our case also underlines the need for lifelong monitoring of patients with thymic NETs and EAS.