THU517 Aggressive Cushing’s: A Rare Case Of Pancreatic ACTHoma In A Young Female

Disclosure: O.C. Reyes: None. A. Sison: None. M. Villa: None. D. Dimayuga: None. Introduction: Adrenocorticotropic hormone-producing pancreatic neuroendocrine neoplasm (ACTHoma) is a rare type of pancreatic neuroendocrine tumor that causes ectopic adrenocorticotropic hormone syndrome. Cushingoid manifestations and metabolic abnormalities can occur rapidly. High index of suspicion is required for early diagnosis. Case: A 31-year-old Filipino female presented with facial and ankle swelling that occurred 6 weeks before the visit. She also had acne, easy bruising, amenorrhea and frequent mood swings. There was reported weight gain of 3 kg a month prior. She had no history of hypertension and diabetes, and had no unusual family history. At the time of admission, vital signs were blood pressure of 130/80mmHg, pulse of 92/min, respiratory rate 20/min and body temperature of 37.2C. Her body mass index was 28kg/m2. She had muscle atrophy of the upper and lower extremities, facial flushing, posterior cervical fat pad, abdominal violaceous striae, and skin pigmentation. Her external genitalia was normal, Tanner Stage 5 consistent with adult pattern. Neurologic exam was unremarkable. She was examined for Cushing’s syndrome. On initial tests, glucose was 406 mg/dl, HbA1C 10.7%, thyroid stimulating hormone 0.122 (NV: 0.55-4.78), Free T3 0.77 (NV: 2.3-4.2), Free T4 0.58 (NV: 0.89-1.76). Creatinine was 0.86 mg/dL, sodium was 140 mEq/L, potassium was 2.1 mEq/L showing hypokalemia. There was leukocytosis on her blood count, white blood cells 15,310/mm3 (neutrophils 94%, lymphocytes 3%). In the low-dose dexamethasone suppression test (DST), the serum cortisol concentration was 991.03nmol/L. Her adrenocorticotrophic hormone (ACTH) level was elevated at 577pg/mL. After high-dose DST, the serum cortisol concentration was > 1750 nmol/L. No tumor was observed on pituitary magnetic resonance imaging. On abdominal computed tomography (CT), a large, lobulated, heterogeneously-enhancing mass arising from the pancreatic body and tail measuring 7.5cm x 10cm x 10.9cm was seen. The mass had infiltrated the gastric fundus, and encased the splenic artery. Multiple non-calcified subcentimeter pulmonary nodules were observed on chest CT. CT-guided biopsy of the pancreatic mass was done. On microscopic examination, numerous atypical cells arranged with small clusters and sheets and scattered singly were found in the tumor. The cells had small to enlarged, hyperchromatic, ovoid to round nuclei and scant to ample delicate cytoplasm. On immunohistochemical staining, the tumor cells were stained positive for synaptophysin and chromogranin A, which are both neuroendocrine markers, as well as ACTH. However, the patient died prior to any definitive management. Conclusion: ACTHoma is a very rare disease that causes hypercortisolemia. Reporting of similar cases will provide insight into its clinical features, immunohistochemical characteristics, diagnosis, therapy, and prognosis. Presentation: Thursday, June 15, 2023