Endocrine Abstracts

Pulmonary neuroendocrine tumors (NET) are well recognized, but quite an uncommon group of disorders to cause ectopic Cushing’s syndrome. Pulmonary NETs have also undergone a change in treatment paradigms. We present a 62 year old female with incidentally detected left lower lobe lung nodule with biopsy proven well differentiated NET with ki67 index of 5–10% in 2011. She had a metachronous slow growing left sided renal tumor (hypernephroma), long standing type 2 diabetes, hypertension, episodic dry flushing and chronic diarrhoea. Clinical examination was normal apart from morbid obesity with a BMI of 40. Whole body FDG -PET CT showed intense FDG uptake within the left lower lobe of lung which involved the pericardium without uptake in lymph nodes or in renal lesion. Both Chromogranin A (29.9 nmol/L) and 24 hr Urine 5HIAA (40 mmol/L) were elevated, thus diagnosis of carcinoid syndrome was made and she received Octreotide LAR 30 mg monthly, with clinical and biochemical resolution. Subsequent imaging showed stable lung lesion and her echocardiograms were normal. Whilst undergoing long term surveillance, 6 years on, she had 2 episodes of bowel ischemia requiring extensive bowel resection resulting in prolonged hospital stay, during which she was off somatostatin analogue therapy for 7 months. In this period, she developed clinical features of Cushing’s syndrome, which prompted biochemical re-evaluation. She failed to suppress on overnight dexamethasone suppression test with the resulting cortisol level being 280 nmo/L (normal response to suppress < 50 nmol/L) with elevated 24 hour urine free cortisol (201 nmo/L and 115 nmol/L over 24 hours) and ACTH of 90.4 ng/L suggestive of ACTH dependent Cushing ’s syndrome. Corticotroph Releasing Hormone (CRH) Test suggested diagnosis of ectopic ACTH secretion. The diagnosis of ectopic Cushing’s syndrome secondary to pulmonary neuroendocrine tumor was made and she was restarted on Octreotide LAR. Within two months of therapy, she demonstrated remarkable clinical and biochemical improvement. This case illustrates the unmasking of ectopic ACTH secretion and changing functionality of a pulmonary neuroendocrine tumor. It is a reminder of the prolonged surveillance and vigilance needed the management of neuroendocrine tumors.