Endocrine Abstracts

Context: ACTH-producing neuroendocrine cancer (NEC) of the thymus is rare. Lymph nodes and bone are most common metastatic sites. ACTH-secreting thymic NEC with pancreatic metastasis was only reported in one case. Most cases presented with florid Cushing syndrome (CS). Our case had thymic NEC with pancreatic metastasis, presenting with intermittent flush instead of typical CS. We demonstrate the comprehensive information of somatostatin receptors (SSTR), three different kinds of positron emission tomography (PET) scans, and the complete treatment course of this rare cancer.

Case description: A 58-year-old female patient presented with intermittent flush associated with sweating and weight loss. The following exams showed mediastinum widening and elevated tumor markers. Further image survey revealed tumors in the mediastinum, pancreas and bones. Ultrasound-guided biopsy of the mediastinum tumor was performed. Pathology with immunohistochemical (IHC) staining resulted in a thymic NEC. SSTR2 and SSTR5 were negative in IHC stain. The mediastinal tumor showed intense fludeoxyglucose, mild 3,4-dihydroxy-6-¹⁸F-fluoro-L-phenylalanine, and mild ⁶⁸Ga-DOTA-tyr3-Octreotide avidity on PET scans. IHC staining of ACTH was positive. Serum and urine cortisol levels elevated, but the patient did not have apparent Cushing appearance. The patient received mediastinum tumor resection followed by radiation therapy, alcohol injection to the pancreatic metastasis lesion, and systemic anti-cancer medications including sandostatin, pasireotide and everolimus. After the initial tumor resection, symptom of flush improved significantly. The 24-hour urine free cortisol (UFC), serum cortisol and ACTH also decreased obviously. However, thymic and pancreatic tumors enlarged gradually under the following systemic treatment. Fluconazole was prescribed for the hypercortisolism. Bilateral adrenalectomy was also suggested but the patient refused. She died from infection 16 months after the diagnosis of NEC.

Conclusions: Pancreatic metastasis and ACTH-secretion should be warrant in cases of thymic NEC even without apparent CS. Intermittent flush could be the initial presentation of patients with ACTH-secreting NEC. Multi-faceted treatments are necessary. SSTR staining and ⁶⁸Ga-DOTATOC PET scan may be reference for treatment choice.