SAT-146 A Rare Combination of Severe Ectopic Cushing’s Syndrome and Graves Hyperthyroidism: A Case Report

BACKGROUND: Ectopic ACTH secretion (EAS) is a rare cause of Cushing’s syndrome. Olfactory neuroblastoma (ONB) is a malignant tumor derived from the olfactory epithelium and can rarely be a source of ectopic hormone production. There are only 19 reported cases of EAS from ONB. We report a case of severe ectopic Cushing’s due to ONB. Interestingly, the patient also presented with Graves disease, which is an unusual pathophysiologic combination since supraphysiologic levels of glucocorticoids suppress the immune system, thereby ameliorating autoimmune processes. Remarkably, Graves disease improved following the removal of the source of ectopic ACTH. CASE PRESENTATION: A 41year old male presented with epistaxis, anosmia, and headaches. He also reported recent weight gain, muscle weakness, and new onset hypertension. Cross-sectional imaging revealed a right nasal cavity mass with intracranial extension. Endonasal biopsy was consistent with a diagnosis of ONB. Biochemical evaluation demonstrated hypokalemic alkalosis, hyperglycemia, and severe hypercortisolism [ACTH 734 (9-46 pg/ml), am cortisol 110 (2-15 ug/ml), late night salivary cortisol 9.8 and 22.53 (<0.09 ug/dl), 24 hour UFC 41,337.3 (4-50 mcg) and non-suppressed cortisol 110 (1.8 mcg/dl) by 1 mg dexamethasone]. Pituitary MRI showed no sellar pathology. Following a period of cortisol suppression with Ketoconazole then with Etomidate infusion, the patient underwent resection of the ONB, followed by chemo- and radiotherapy, which resulted in improvement of severe hypercortisolism. Histopathology showed positive ACTH immunostaining. Pre-operative evaluation also demonstrated hyperthyroidism: TSH <0.010 (0.3-5uIu/ml), FT4 3.11 (0.89-1.76 ng/dl), normal TT3 0.81 (0.6-1.81 ng/ml). Thyroid auto-antibodies were negative; however, radioiodine scan and uptake demonstrated diffusely increased uptake in the enlarged thyroid gland. Pre-operative euthyroidism was achieved with a combination of methimazole, SSKI and cholestyramine. After 6 months of methimazole therapy the patient presented with hypothyroidism (TSH 72.37, FT4 0.1). Methimazole was discontinued and he achieved euthyroidism on subsequent evaluations. CONCLUSION: EAS due to ONB is a very rare cause of Cushing’s syndrome. To our knowledge, this is the first reported case of a male presenting with EAS and concurrent Graves hyperthyroidism. An extensive review of the literature and seeking expert opinion did not provide a convincing pathophysiologic explanation to this unusual concurrence. We therefore hypothesize that, while the two endocrine conditions were simultaneous, they were likely unrelated.