Abstract
Disclosure: V.A. Kothari: None. Here we present the diagnostic journey of a patient with Cushing's syndrome attributed to a rare and elusive culprit—a neuroendocrine tumor that aberrantly produces adrenocorticotropic hormone (ACTH). An 83-year-old female with PMH of Graves' disease well-controlled on methimazole 5 mg daily presented w/ AMS & worsening weakness and was found to have severe hypokalemia w/ K of 2.2. A CT chest done a month prior for bronchitis showed a right lower lobe lung nodule and a prior CT Abd also done a month prior showed an incidental pancreatic cyst of 1.5 cm and bilateral adrenal thickening. In addition, the patient had progressively worsening diabetes and proximal muscle loss. Patient was started on K supplementation and also spironolactone. A renin and aldosterone level were obtained which were 0.47 and <1, respectively which ruled out hyperaldosteronism. Her insulin requirements had significantly escalated. Given the patient's skin changes with petechiae along with the findings above, the patient underwent a low-dose DST twice which showed elevated AM cortisol of 76.4 & 69.6 respectively. Dexamethasone level was appropriately elevated at 217. ACTH was 149. A 24 hr urine cortisol was repeated twice and showed 4477.6 and 7107.2 respectively. MRI brain showed a flatten pituitary and empty sella. Amiloride and ketoconazole were started. Spironolactone was increased to 200 mg. Ga-68 DOTATE PET/CT was done however did not show a distinct source lesion. A few weeks later,the patient again had to go to ER due to profound hyperkalemia and hyponatremia. Her medications were adjusted. While hospitalized, she underwent biopsy and cryoablation of the right lung nodule w/ subsequent immediate reduction in ACTH levels. However, although the ACTH level initially declined and a subsequent CT chest also showed the ablation zone to encompass the whole tumor, the patient again had worsening of ACTH & cortisol causing hypokalemia again. It was unclear if the patient's active Cushing's disease was due to residual tumor or other areas of carcinoid as the lung nodule was dotatate and FDG negative. Given the active Cushing's disease, ketoconazole 200 mg BID was restarted. Her condition continued to worsen despite escalating doses of ketoconazole. Due to proximal myopathy, she was unable to ambulate on her own requiring significant assistance. Definitive treatment was discussed with the patient and her family given the progressive functional decline. Broached adrenal ablation versus adrenalectomy was discussed and bilateral adrenalectomy was eventually decided upon and scheduled. This case highlights the rare occurrence of ectopic ACTH producing neuroendocrine tumors causing Cushing's syndrome. It underscores the need for advanced diagnostic approaches and collaborative healthcare efforts in managing uncommon endocrine disorders. Presentation: 6/2/2024