Laparoscopic resection of VIPoma presenting at an unusual location.

VIPoma is an extremely rare neuroendocrine tumour. Majority of the lesions occur in the pancreas. There is usually a long and recurrent history of secretory diarrhoea. Current diagnostic methods help in diagnosing a VIPoma once it is suspected. We herein report a case of VIPoma which had the delay in diagnosis and presented at an extremely unusual location (pyloroduodenal) who underwent laparoscopic resection for the same.

INTRODUCTION

VIPoma is a rare neuroendocrine tumour (NET), with reported incidence of 1 in 10 million population.[1] The diagnosis is often missed for several months or years and thereby mismanaged. We herein report a case, of VIPoma presenting as watery diarrhoea, hypokalaemia, achlorhydria, WDHA syndrome arising from an unusual site (Pyloroduodenal [PD]) who underwent a laparoscopic antrectomy and segmental duodenal resection with Billroth II reconstruction.

CASE REPORT

Fifty two-year-old man presented with repeated episodes of watery stools (15–20) of 3 years duration and a weight loss of 20 kg during this period. Clinical evaluation revealed stable haemodynamics but has dehydration. His initial evaluation showed dyselectrolytemia (Hypokalaemia, achlorhydria) and metabolic acidosis. He gave the history of repeated hospital visits during episodes of watery diarrhoea and dyselectrolytemia that raised suspicion of VIPoma, which lead to his evaluation as follows. Laboratory parameters showed haemoglobin was 14 g/dL, total leucocyte count 7000/Cumm, serum albumin 3.8 g with normal serum calcium levels and coagulation profile. He had no family history of MEN1 syndrome and evaluation by an Endocrinologist for screening of MEN 1 syndrome was found to be negative. The patient had no hypercalcaemia. After intravenous hydration, Injection octreotide (intravenous 100 mcg thrice daily), and correction of dyselectrolytemia he underwent further evaluation. Upper GI endoscopy showed submucosal lesion at the PD region. His serum VIP levels were 892 pg/ml. Multidetector computerised tomography (MDCT) abdomen showed an enhancing lesion in the arterial phase and washout in the venous phase, measuring 1.7 cm × 1.6 cm in size [Figure 1a-c). A Ga-68 dotate Positron emission tomography-Computed tomography (PET-CT) scan showed intense uptake by the lesion, with no uptake seen in the regional lymph nodes or elsewhere [Figure 1d]. His cardiac status was normal and his performance status was SWOG 2.

Figure 1

(a) Intense enhancement of Pyloroduodenal lesion in arterial phase (white arrow). (b) Washout from lesion in venous phase (white arrow). (c) Coronal section showing lesion (white arrow). (d) Corresponding coronal section on Ga-68 dotatate positron emission tomography-computed tomography showing the lesion (white arrow)

An informed consent was obtained for surgery and he underwent a laparoscopic antrectomy and segmental duodenal first part resection. The patient was placed in a supine leg split position and standard ports for the foregut procedure were inserted after creating a closed pneumoperitoneum (14 mm Hg). The port positions were, 10 mm camera port at the umbilicus, right- and left-hand working ports (5 mm) an inch above the level of umbilicus in the midclavicular lines, epigastric (5 mm) for retraction and 12 mm port in the left anterior axillary line below the level of the umbilicus (for retraction, stapling). Staging laparoscopy was done. Tumour was seen in the PD region [Figure 2a]. Lesser omentum was progressively opened in an avascular region. The gastroepiploic vessels were secured with clips and divided. The first part of the duodenum was dissected and looped and blue load 60 mm, Endo GIA (Medtronic Inc) was used to divide the duodenum one cm beyond the tumour [Figure 2b]. The antrum was transected 4 cm proximal to the pylorus with Endo GIA (purple 60 mm) [Figure 2c]. While the perigastric lymph nodes were removed en-bloc with antrectomy, the enlarged common hepatic and proper hepatic lymph nodes were removed separately sent for histopathology for the routine staging of the disease. A loop stapled gastrojejunostomy [Figure 2d] was performed using an Endo GIA (blue 60 mm) and the staple entry site was closed with running 3-0 vicryl suture.

Figure 2

(a) Lesion at Pyloroduodenal region (white arrow). (b) Duodenal staple transection. Lesion (white arrow). (c) Proximal transection of antrum with Endo GIA stapler. (d) Stapled gastrojejunal anastomosis

The operative time was 120 min and blood loss was minimal. He made an uneventful postoperative recovery. Histopathology showed NET with no metastasis in lymph nodes, and immunohistochemistry showed synaptophysin and chromogranin A positivity with Ki-67 index of <2%. Serum VIP levels were not done in the early postoperative period. Serum VIP levels at 1 year and 2 years of follow-up were 40 and 33 pg/ml, respectively. Ga-68 dotatate PET-CT showed no locoregional recurrence or distant metastasis.

DISCUSSION

Most patients with chronic diarrhoea are managed by general physicians. The usual causes under consideration would be infective, inflammatory bowel disease, malabsorption and irritable bowel syndrome. VIPoma's are not considered in the differential diagnosis because of their rarity. A high index of suspicion in patients with recurrent watery diarrhoea (secretory) with dyselectrolytemia would be the first step toward the diagnosis of this rare condition as in the present case. Furthermore, weight loss is a common accompaniment reported by others.[2]

Majority of VIPoma arise from the pancreas, peri ganglionic tissues, retroperitoneum, lung, bronchus and liver. The potentially curative therapy for these patients is complete resection of tumour. Depending on the stage of the disease, this may entail major resection of the pancreas and adjacent structures, liver resection or pulmonary metastasectomy, which clearly leads to long-term survival. There are limited data on the laparoscopic approach in managing VIPomas. Ga-68 dotatate PET-CT clearly showed a solitary lesion, corroborated at the surgery. Regional lymphnode sampling was done in our patient for the purpose of staging. Control of the symptoms in patients with unresectable disease can be achieved by somatostatin analogues. Systemic chemotherapy may help in a minority of these patients.[3] A Medline search did not show any previous report of a VIPoma in the PD region, and we believe this to be the first reported case.

The diagnosis of VIPoma once suspected can be established by measuring serum levels of VIP. Control of diarrhoea can be usually achieved with octreotide and further supports the diagnosis. MDCT of the abdomen would help localise these tumours. Apart from localising the tumour, Ga-68 dotate PET-CT would help in detecting regional lymph node metastasis and distant disease.[4]

Octreotide controls the symptoms of VIPoma's during acute presentation with diarrhoea and is useful in those with unresectable distant disease for palliation of chronic diarrhoea. The definitive treatment for cure would be surgical resection as in the current report. Curative surgery may still be possible in those with locoregional disease and liver metastasis amenable for resection.[5]

CONCLUSION

Diagnosis of VIPoma requires a high index of clinical suspicion. Confirmation of the diagnosis is by measuring serum VIP levels and staging is done with Ga-68 dotate PET-CT. Laparoscopic resection is safe and feasible for a PD region VIPoma.

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Conflicts of interest

There are no conflicts of interest.