Endocrine Abstracts

A 67 year-old man, with metastatic prostate cancer diagnosed in July 2015, presented with a two-week history of lethargy, intermittent confusion, facial flushing, and increased thirst. Other medical history included well-controlled hypertension on irbesartan monotherapy, and paroxysmal atrial fibrillation. On examination, he was flushed and lethargic, but had no other features of Cushing’s Syndrome. His pulse was 66 bpm and BP 179/78. There was no evidence of hypovolaemia or infection.

Bloods revealed potassium 2.1 mmol/l, chloride 97 mmol/L, bicarbonate 43 mmol/L and glucose 18.1 mmol/L. His ECG showed a long QTc and widespread T wave inversion. Other routine bloods were unremarkable. Two random cortisol levels 12 hours apart were 1601 nmol/L and 1785 nmol/L, with ACTH of 301 nmol/L. Following an overnight 1mg dexamethasone suppression test, the morning cortisol failed to suppress (1741 nmol/L).

He was managed as prostate cancer associated with ectopic ACTH secretion and Cushing’s Syndrome. He was commenced on metyrapone with ketoconazole subsequently added, IV and oral potassium replacement and gliclazide.

The case was reviewed at the local neuroendocrine tumour and prostate cancer MDTs. Review of histology from August 2015 showed prostatic adenocarcinoma with neuroendocrine differentiation. The original biopsy was negative when subsequently stained for ACTH. His prognosis was poor and therefore he was managed medically; oncology administered emergency chemotherapy, followed by further palliative chemotherapy. Cortisol levels have subsequently been maintained within normal range on low-dose metyrapone.

An extended literature search revealed one other case with a similar presentation to our patient (Alwani RA et al. 2009). Treatment modalities are limited, as definitive treatment is surgical. There is limited evidence that medical therapy is effective in lengthening survival of affected individuals.