A 71 y.o. ex-smoker presented with several months of nausea, anorexia, weight loss, vague upper abdominal discomfort. Subsequent investigations diagnosed FDG-PET avid atypical lung carcinoid with hepatic metastasis. Ga-68-Dototate PET scan revealed low-grade somatostatin receptor expression in the left upper lobe with left suprahilar mass only. He underwent systemic chemotherapy with capecitabine, temozolamide. Following completion of chemotherapy and cessation of dexamethasone, he was noted to 10kg weight gain with moon-like facies, hyperglycemia, bilateral pitting oedema. Re-staging FDG-PET imaging revealed partial metabolic response. Blood pressure was 150/80mmHg despite increase of felodipine dose.
Serum cortisol was elevated at 1034nmol/L (range 110-550nmol/L) with an ACTH of 97pg/ml (range <46pg/ml), potassium was 2.9 mmol/L. MRI pituitary did not identify any pituitary lesion. Low and high dose dexamethasone suppression tests suggested ectopic ACTH secretion. Adrenal enzyme blockade with metyrapone was commenced with addition of ketoconazole. There was initial concern of persistent hypercortisolism (>800 nmol/L) despite up-titration of therapy, however this was due to the cross-reactivity of upstream adrenal metabolites due to enzyme blockers. Subsequent serum cortisol levels performed on liquid chromatography-tandem mass spectrometry (LC-MS) was at target (300 nmol/L).
Since his cortisol, potassium, blood pressure and glucose were controlled on dual adrenal enzyme blockade, and FDG-PET was stable, further systemic therapy was not given. However he developed profuse secretary diarrhoea with mildly elevated 24 hr urine 5-HIAA and elevated gastrin (305 pmol/L, range 6-55) with normal endoscopies. Diarrhoea resolved after commencement of somatostatin analogue injection. He is awaiting repeat Ga-68-Dototate PET to assess suitability for peptide receptor radionuclide therapy given his ectopic ACTH/gastrin secretory neuroendocrine tumour.