Endocrine Abstracts

JOINT4032

We present a rare case of a 64-year-old female with no relevant past medical history, who presented in October 2023 with a 2-month history of peripheral and facial oedema, hirsutism, sleep disturbance, muscle weakness, brain fog and new onset hypertension. She also reported some initial weight loss, so a CT of the chest, abdomen and pelvis was arranged. This revealed hyperplastic adrenal glands but no other significant findings. She was found to have a raised random cortisol (1126 nmol/l) with a high adrenocorticotropic hormone (ACTH) (98ng/l, reference ≤ to 50ng/l) and was referred to Endocrinology with suspicion of ACTH-dependent Cushing’s syndrome. Her overnight dexamethasone suppression test was markedly elevated at 621 nmol/l (reference 0-50 nmol/l), as was her 24h urinary free cortisol (886 nmol/24h, reference 0-146 nmol/24h). The rest of her anterior pituitary profile was unremarkable. An MRI of her pituitary gland revealed an incidental 3 mm Rathke’s cleft cyst, but no adenoma. Inferior petrosal sinus sampling (IPSS) was arranged 3 months after her initial presentation to exclude Cushing’s disease. However, the patient reported spontaneous resolution of her symptoms, with normalisation of her blood pressure and biochemistry. A diagnosis of cyclical ACTH-dependent Cushing’s syndrome was made. In June 2024, the patient’s symptoms recurred, with concurrent biochemical evidence of hypercortisolism, and an urgent IPSS was arranged. This did not confirm a pituitary origin and an 18-FDG PET-CT and a pituitary and thoracic 11C-Methionine PET CT were performed to identify an ectopic origin of ACTH secretion, without any focal uptake noted on either scan. A Gallium-68 DOTATATE PET CT was arranged to look for neuroendocrine tumours as an ectopic source of ACTH and revealed focal uptake in the small bowel and 2 mesenteric lymph nodes, suggestive of a small bowel neuroendocrine tumour (NET) as the source of ectopic ACTH secretion. She was commenced on block and replace therapy with metyrapone and dexamethasone, as well as apixaban for thromboprophylaxis. She underwent surgical resection with intraoperative ultrasound guidance of two tumours found in the ileum, as well as the pathological mesenteric lymph nodes identified on PET CT, with perioperative hydrocortisone and octreotide cover. Hydrocortisone was stopped 2 weeks post-operatively following a robust early morning cortisol result and post-operative ACTH levels normalised. Histopathology confirmed a grade 2 well-differentiated mid-gut NET expressing ACTH with nodal metastases. She remains under regular endocrine follow up and is awaiting a repeat Gallium-68 DOTATATE PET CT to guide further management.