Endocrine Abstracts

A 62-year-old lady was assessed following discovery of a retroperitoneal tumour on a CT scan. Fifteen years previously she was diagnosed with irritable bowel syndrome with alternating constipation and diarrhoea, however, within the last 5 years, diarrhoea was the dominant feature with bowel opening every 20 min daily. Investigations for inflammatory bowel disease, hyperthyroidism and coeliac disease were negative. Her anal sphincter was found to be non-functioning and a colostomy was performed privately to improve her symptoms, but large volumes of stool continued to be passed daily. An episode of right upper quadrant abdominal pain led to imaging and subsequent referral. She had never been aware of any symptoms such as skin rashes or hypoglycaemia, and her weight was stable. Two years previously she had experienced episodes of palpitations and sweating, although these had resolved and appeared to coincide with menopause. There was no significant family history and clinically, she was not hypertensive.

CT demonstrated a 7 cm multi-cystic retroperitoneal tumour adjacent to the tail of the pancreas but uncertainty about pancreatic or adrenal origin. Octreotide uptake was mildly avid. Laboratory investigations showed a markedly elevated vasoactive intestinal peptide (VIP) at 100 pmol/l and urinary dopamine (12 768 mmol/24 h) with normal urinary adrenaline and noradrenaline. Plasma metanephrines confirmed elevated normetanephrine (18 562 pmol/l)

Given these findings, phenoxybenzamine was commenced to optimise blood pressure and a left adrenalectomy was performed. Histology confirmed complete excision and immunohistochemistry was consistent with a phaeochromocytoma. VIP immunoassay was inconclusive due to high background staining, however, a fasting gut hormone profile post operatively confirmed complete normalisation of VIP levels (6 pmol/l) as were plasma normetanephrine (532 pmol/l), suggesting hormone co-secretion. Furthermore, stoma output slowed considerably to normal volumes. We present an unusual case with complex biochemistry that highlights the importance of paying heed to the patient history.