PMON123 Diagnostically Challenging Case of Cushing's Syndrome from a Pancreatic Neuroendocrine Tumor Treated with Radiofrequency Ablation
Authors: Gugger Aristea Sideri , Fang Jiali , Virk Renu , Ahmad Umar , Sagredo Jorge Ariazza , Visrodia Kavel H , Wilson Gabrielle Page 
Published: November 2022

Abstract

Background
The delayed diagnosis of Cushing's syndrome (CS) results in advanced disease, treatment delays and poor outcomes. We present a patient with ectopic ACTH-syndrome (EAS) from a pancreatic neuroendocrine tumor (NET) whose care posed significant diagnostic and therapeutic challenges.

Clinical Case
59F with classic Cushing's stigmata (including striae, plethora, supraclavicular and dorsocervical fat pads, muscle wasting), and two-year history of rapid weight gain, hypertension, T2DM, hyperlipidemia, severe osteoporosis complicated by multiple vertebral compression fractures, presented for workup and management of ACTH dependent CS. CS was confirmed (Baseline: ACTH 96 [7.2-63.3 pg/ml], serum cortisol 19.6 [4.8 - 19.5 mcg/dL]; LDSST: cortisol 18.5 [&lt;1.8 mcg/dL], dexamethasone 547 [&gt;200 ng/dL]; 24-hour Urine Free Cortisol: 191.60 [&lt;45 mcg/d], 24-hour Cr 484 mg/day; LNSC: 436, 464 [29-101 ng/dL]; 8 mg ODST cortisol 7.2 mcg/dL). Pituitary MRI showed possible 0.5 cm left anterior pituitary lesion. Inferior petrosal sinus sampling (IPSS) to differentiate between Cushing's disease and EAS was initially planned, however, her course was complicated by an NSTEMI and acute/subacute lacunar infarcts in the left parietal and frontal lobes, and IPSS was deemed contraindicated. Additional workup was pursued including POMC 154 [&lt;40 fmol/ml], Chromogranin A 538 [0-103 ng/ml] (on pantoprazole), pancreatic polypeptide 798 [0 - 435 pg/mL], 24-hour 5HIAA/Creatinine 3 [0 - 15 mg/24hr]. Chest/Abdominal/Pelvis CT showed a 1.5 cm incidental lipid rich adrenal adenoma; workup was negative for pheochromocytoma/ Conn's tumor/ adrenocortical carcinoma. Given elevated POMC and clinical suspicion for EAS, the patient underwent 68Ga-DOTATATE PET-CT scan which revealed an avid 7 mm lesion (SUVmax 14.5) in the pancreatic tail suspicious for a pancreatic NET- the presumed ectopic source of ACTH. Given the patient's poor functional status she was not a candidate for tumoral resection via distal pancreatectomy. Ketoconazole was initiated for treatment of hypercortisolism with good biochemical control, but the patient developed liver toxicity. The decision was made to pursue endoscopic ultrasound guided biopsy and radiofrequency ablation of the lesion. Pathology confirmed ACTH immunoreactive low-grade pancreatic NET. Post-procedure, morning ACTH was 8 pg/ml and cortisol was 9.1 mcg/dL, and the patient required steroids for relative adrenal insufficiency. Further follow up with repeat POMC, cortisol, ACTH levels, 24-hour UFC is required to monitor response.

Conclusion
IPSS is the gold standard test for differentiating Cushing's disease from EAS but is only available in select centers and for suitable candidates. This case supports the potential utility of POMC peptide measurements in the differential diagnosis of CS and the use of advanced nuclear imaging modalities for tumor localization. For patients with functional pNET who are poor surgical candidates or intolerant of pharmacotherapy, novel endoscopic ablation may offer a lower risk therapeutic option and its use should be further investigated.
Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.