Endocrine Abstracts

61 year male presented with productive cough and was noted to have persistent hypokalaemia. On examination he had an elevated blood pressure; previously not known to be hypertensive and significant proximal myopathy in his lower limbs. He also had central obesity. In October 2018 he had a left parotid swelling. He had left parotidectomy and left neck dissection. The histology was an adenocarcinoma. In the following year he had cough, and shortness of breath, which on investigation showed a left pleural effusion. He had a VATS procedure and histology showed metastatic adenocarcinoma to lung from the parotid. His potassium levels ranged from 2.8–3.45 mmol/l litre with raised urinary potassium. Cushing’s syndrome was suspected so low dose dexamethasone test(LDDST) was done. 24 hour urine cortisol was also requested, as well as ACTH. The baseline cortisol was 10595 nmol/l and after 48 hrs after LDDST the cortisol was 4425 nmol/l. ACTH was 1105 ng/l which was suggestive of ACTH dependent Cushing’s syndrome. MRI pituitary was normal. 24 hour urine cortisol was 11585 nmol/l. Ectopic ACTH production was suspected and patient was started on Metyrapone 250 mg tds. A week later the patient was admitted with hypokalaemia, atrial flutter and fluid overload. The metyrapone dose was increased to 500 mg tds. He had similar admissions with recurrent hypokalemia, oedema and shortness of breath and metyrapone was increased to 1g tds. Spironolactone and losartan was also given. In spite of this 24 hour cortisol kept increasing to 19785 nmol/l. His CT chest also showed progression of lung metastasis. He was admitted to hospice and sadly passed away. Parotid carcinoma producing ACTH is exceedingly rare. Only less than 10 cases have been described in literature. Ectopic ACTH producing malignancies can be very difficult to treat even with rapidly increasing metyrapone doses.