Pancreatic Endocrine Surgery

The majority of endocrine tumours of the pancreas are insulinomas and gastrinomas, but a variety of other tumours are also seen, with differing clinical syndromes related to their hormone secretion. These syndromes can result in life-threatening illnesses, such as, the profound hypoglycaemia of insulinoma and the debilitating ulcer disease of gastrinoma, due to over production of hormone.

After the clinical syndrome ofthe excess hormone production has been recognised, a process which can take years, appropriate investigations can be undertaken to confirm the diagnosis and localise the tumour. Besides the non-invasive imaging modalities, the authors favour all patients undergoing angiography and calcium-stimulated venous sampling for accurate localisation and subsequent safe and successful surgery.

The only curative treatment for patients with insulinoma and gastrinoma is surgical resection. In the authors' unit the preferred approach to resection of an insulinoma is either laparoscopic enu-cleation or laparoscopic distal pancreatectomy, while gastrinomas, which are often located in the duodenal wall, are generally removed by open surgery. Intra-operative ultrasound (IOUS) is a vital adjunct, particularly in laparoscopic resection, to check on the position of small tumours not readily visible to the surgeon. It will locate 90 to 95% of insulinomas, and when combined with preoperative localisation with calcium-stimulated angiography and venous sampling, result in a cure in nearly all patients.35,36 IOUS enables visualisation of the tumour's relationship to the main pancreatic duct (MPD) and vessels, as there is a higher risk of pancreatic fistula if enucleation is undertaken of a tumour abutting the MPD.36

Laparoscopic resection of insulinoma

The laparoscopic approach to the pancreas is with the patient lying supine and with four or five ports placed to enable full mobilisation of the pancreas, if necessary. Haemostasis can be achieved with either hook diathermy or with ultrasonic shears, but the latter is preferred. After a window is opened in the gastrocolic ligament, laparoscopic ultrasound can be performed to localise the tumour and determine the relative safety of enucleation versus distal

37,38

pancreatectomy.37,38

Enucleation of an insulinoma is reserved for benign, solitary tumours, less than 2 cm in diameter, located on the surface of the pancreas and not in contact with the MPD, main splenic vessels, or portal vein. Enucleation can be performed with ultrasonic dissection that will control small pancreatic vessels, supplemented by the application of ligaclips, if necessary. After the tumour has been removed and placed in a bag for extraction, the bed is closely inspected for haemorrhage and pancreatic leak, the latter occurring in approximately 18% of patients.37 Additional suturing and application of fibrin glue may diminish the risk of haemorrhage and fistula formation, but there is little evidence to support this as yet39 and is not the practice of the authors.

If the tumour is close to the MPD and there is no margin of normal pancreatic tissue, then distal pancreatectomy should be undertaken, preferably laparoscopically and with preservation of the spleen. The transaction of the pancreas is performed with a laparoscopic linear stapler (EndoGIA, US Surgical, Norwalk, CT, USA) that will control vessels within the parenchyma and the MPD, but additional intra-corporeal suturing or use of ligaclips may be required. Fibrin glue can be applied at the discretion of the surgeon, but there is no evidence that this reduces the rate of fistula formation. Splenic vessels can be readily controlled with ligaclips or the harmonic scalpel.

Open resection of endocrine tumours

Both enucleation and distal pancreatectomy for insulinoma can be undertaken as open procedures, utilising the same surgical principles and techniques for haemostasis, as in laparoscopic resection. Gastrinomas are usually approached at open surgery, however, because of the likely location of the primary tumours in the duodenum and the possibility of metastatic spread to local lymph nodes. Routine duode-notomy and palpation of the duodenal wall increases the detection rate of gastrinomas, which may be multiple, and it makes cure more likely.40

Gastrinomas may be found anywhere in the gastrinoma triangle (Fig. 6), therefore, good access is required to the whole of the upper abdomen, including the whole of the pancreas, regional lymph nodes, and liver. Primary tumours are frequently small, most commonly in the proximal duodenum, and associated with regional lymph node metastases in 60% of patients.41 Approximately 10% of cases have primary gastrinomas within lymph nodes, without any identifiable primary tumour.42 An extensive exploration is required, including duodenotomy and palpation, plus routine removal of local

Fig. 6 Diagram of the gastrinoma triangle.

nodes. This can be safely achieved with conventional techniques of haemostasis, with sutures, ligaclips, and diathermy.

Pancreatic and duodenal operations, either laparoscopic or open, require drainage to deal with any potential pancreatic leakage that might become secondarily infected and have the potential for secondary haemorrhage.

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