Endocrine Abstracts

Introduction: Ectopic Cushing syndrome caused by a neuroendocrine tumor is uncommon and it’s diagnosis is often delayed. Optic neuritis is another rare disease, with some cases also associated to neuroendocrine tumors.

Case-report: A 43-year-old female was referred to the endocrinology outpatient’s department due to obesity. She had a past history of bilateral optic neuritis of unknown etiology. She complained of weight gain, hair loss, acne, hirsutism, proximal muscle weakness and visual hallucinations. Physical examination revealed facial plethora, moon facies, supraclavicular fat pads, acne, central obesity, purple striae, ecchymosis, edemas and moderate hypertension. Laboratory evalution showed an elevated ACTH (80–100 pg/ml) and cortisol (20–30 mcg/dL), the latter without a circadian rhythm. Dexamethasone prolonged low and high doses suppression tests showed absent cortisol suppression and the CRH stimulation test did not show an increase in ACTH levels. Pituitary MRI did not reveal any lesion and the inferior petrosal venous sinus catheterization suggested an ectopic origin of the ACTH. A Cushing’s syndrome due to an ectopic production of ACTH was admitted, but the imaging study, including chest, abdominal and pelvic CT and MRI scans and an octreotide scintigraphy did not reveal the primitive tumor. The patient was treated with metirapone with non-sustained reduction of cortisol levels nor clinical improvement. Therefore she was submitted to bilateral adrenalectomy, with clinical resolution of Cushing’s symptoms and signs, while maintaining raising ACTH levels (189 pg/ml). 14 months after adrenalectomy a new octreotide scintigraphy revealed a right perihilar mediastinic nodular lesion, with a PET scan showing a hypercaptant image at the same location. Nevertheless, the lesion did not appear on the respective CT nor on MRI scans. Tumor marker chromogranin A, started to rise (263 nmol/L), despite a normal value of 5-Hydroxyindoleacetic acid. A right paramedian pretracheal mass was finally documented on the PET-CT 4 years later. The tumor was removed and the histology revealed a neuroendocrine tumor of lung origin. No recurrence was detected until the present date (55 year-old).

Discussion: Optic neuritis and Cushing syndrome have both been described as paraneoplastic syndromes. However, we haven’t found any case described in the literature, combining both syndromes as a result of a neuroendocrine tumor. This case also highlights the long delay that can occur between the paraneoplastic syndromes diagnosis and the neuroendocrine tumor localization.