Education Resource from the Society for Endocrinology
J Britton
Oxford
Summer School 13-16 July 2004
St Anne's College, Oxford University,
UK
Endocrinologists and pancreatic surgeons share a common disease, diabetes mellitus, and a rare problem, pancreatic endocrine tumours. The former is relatively easy to manage; the latter are difficult.
Most surgeons successfully manage most diabetics on their own. But patients with severe acute pancreatitis or after a pancreatic resection usually benefit from endocrine advice. The sliding scale has been the invaluable standby for surgeons for many years. It is easy to use, inherently safe and well understood by everyone. But converting a patient back to a regular twice-daily regime is not always so easy. Specialist advice is also often needed after a partial pancreatic resection and always after a total pancreatectomy. For these latter patients the disease is often a new experience and they require help, often best provided by specialist nurses, with the details of injections and pens and all the other paraphernalia that goes with being a diabetic. Surgeons, however, are not able to advise about the most suitable regime or the type of insulin to use. Furthermore metabolic function is disturbed in most of these patients and there is often, at least initially, some impairment of gastrointestinal function.
Patients with severe acute pancreatitis require help from a number of specialists but endocrinologists are often well placed to interpret and manage the severe metabolic disturbances that are usually found in these patients, which is often compounded by sepsis and the need for long term enteral or parenteral nutrition. Many of these patients end up diabetic and the fluctuating clinical course over many months can be very difficult to manage. For a few patients the natural process of healing allows the pancreas to recover and their insulin requirements gradually diminish over the months and years after their discharge from hospital.
The role of the endocrinologist here is to make the diagnosis and to find the tumour. The surgeon’s job is to find the tumour and then to remove it in the most appropriate way if that is possible. Neither task is easy. The first difficulty for the physician is to think of the diagnosis. Once considered an insulinoma is not difficult to confirm. And in truth the other endocrine tumours have well defined symptoms and signs and relatively easy methods of confirming the diagnosis with hormone assays. Non functioning endocrine tumours usually present to the surgeon directly either as a mass lesion or because of obstruction to another vital structure.
Finding the tumour is another matter altogether. The literature is littered with claims for this investigation and that test. In truth no one investigation is guaranteed to find an insulinoma although recent developments are making things easier. From my perspective at the moment the right way to find an insulinoma is to do a conventional ultrasound examination followed by an contrast enhanced pancreatic MRI scan. If the skill is available this should be followed by an endoscopic ultrasound. If the tumour is visualised all well and good but in any event once a diagnosis of insulinoma is made the patient needs an exploration by a surgeon who knows their way around the dark corners of the pancreas and can use an ultrasound probe directly on to the pancreas during the operation if the tumour is not immediately found. Fortunately an insulinoma has a characteristic appearance on ultrasound. More sophisticated investigations such as portal venous sampling should be reserved for the rare cases when a tumour cannot be found after a thorough exploration.
Most insulinoma are solitary. There is nothing more depressing for the surgeon to remove an apparently isolated tumour for him then to be told by the endocrinologist that the hypoglycaemia has recurred. But occasionally that happens. In about one in ten patients there are multiple tumours and the surgeon should be aware of this at the time of the primary exploration. In general blind pancreatic resections should not be done for an unidentified insulinoma but when there are multiple adnomata then some form of planned resection will be required.
Most insulinoma are benign. At least half the patients with a gastrinoma, a glucagonoma and a vipoma have metastatic disease at the time they present. Many gastrinoma are found in the duodenum and this must be removed in any patient where surgery is a feasible option. Somatostatinomas, which present in the pancreas itself, tend to be malignant and are often not removable. Somatostatinomas that present in the duodenum, often around the Ampulla of Vater, are more benign and are usually removable with a classic pancreatico-duodenectomy. Non-functioning pancreatic endocrine tumours are always malignant and usually inoperable. Carcinoid tumours do develop in the pancreas, usually around the ampulla, and can often be removed. The carcinoid syndrome only develops when they metastasise which, in the authors experience, is unusual.
The opinions expressed in this paper are those of the speaker and do not necessarily reflect the views of the Society
Revised:
05-Nov-2004