A VIPoma Case Study: clinical presentation and management.
McCabe-Robinson OJE, Rodger VJ, Jalota PJ, Prouten J, Levy MJ.
University Hospitals of Leicester.
A 58-year-old man went to India in 2011 and returned with significant diarrhoea. He was passing watery motions up to 15 times a day. Initially, this was assumed to be an infective cause but the stool cultures and microbiological investigations were normal. Subsequently, he had upper and lower endoscopic investigations which revealed no structural pathology. His diarrhoea continued and he developed a profound metabolic hypokalaemic alkalosis (serum potassium 2.1 mmol/L). Further investigations revealed an elevated VIP level (191 pmol/L: NR 0-30) and a high chromogranin A (101 pmol/L: NR 0-60). A CT scan of his abdomen revealed a 4cm mass in the tail of the pancreas with peri-tumoral lymph nodes. Part of the tumour was shown to be entering into the splenic vein; there was also a probable 35mm umbilicated liver metastasis present. A laparoscopic exploration and liver biopsy confirmed a neuro-endocrine tumour and subsequently the patient underwent a subtotal pancreatectomy, splenectomy, extensive lymphadenectomy and partial liver resection in January 2013. The histology confirmed a low-grade neuro-endocrine lesion extending to the posterior surgical resection margin. Post-operatively the patient’s diarrhoea completely resolved and the VIP level lowered to 36 pmol/l and the chromogranin levels were normal. Unfortunately 15 months later, his symptoms returned and he was re-admitted with a hypokalaemic alkalosis after several months of persistent diarrhoea. His VIP levels had risen again to 184 pmol/L. Prior to this admission, he had a repeat CT scan that showed enlargement of a single liver lesion, which was concordant with the octreotide scan. His hypokalaemia and diarrhoea were managed acutely with intravenous fluids, potassium replacement and octreotide (initially 200µg subcutaneous TDS), which was then changed to an octreotide infusion (400 µg over 24 hours). His diarrhoea settled and he was medically optimised before undergoing a second liver resection to remove the presumed solitary metastasis.
This is a very interesting case of VIPoma-induced diarrhoea presenting with classical hypochloraemic, hypokalaemic alkalosis (Verner Morrison Syndrome). We would like to discuss the potential options for this man after surgery in terms of whether adjuvant therapy is indicated.