Duodenal
tumours
Benign
duodenal tumours
Duodenal villous adenomas occur principally in the periampullary
region. Although generally uncommon, they are often found in patients with
familial adenomatous polyposis. Indeed, malignant transformation in such
adenomas is the commonest cause of death in patients with polyposis who have had
the colon removed. The appearances are similar to those adenomas arising in the
colon and, as they have malignant potential, should be locally excised with
histologically clear margins.
Endocrine
tumours
A number of endocrine neoplasms occurs in the duodenum. It is a common
site for primary gastrinoma (Zollinger—Ellison syndrome). Other endocrine
tumours include carcinoid tumours that, by comparison with ileal carcinoids, are
uncommon.
Zollinger—Ellison
syndrome
This syndrome is mentioned here because the gastrin-producing endocrine
tumour is often found in the duodenal loop, although it also occurs in the
pancreas, especially the head. It is a cause of persistent peptic ulceration.
Before the development of potent gastric antisecretory agents the condition was
recognised by the sometimes fulminant peptic ulceration which did not respond to
gastric surgery short of total gastrectomy. It was also recognisable from
gastric secretory studies in which the patient had a very high basal acid output
but no marked response to pentagastrin, as the parietal cell mass was already
near maximally stimulated by pathological levels of gastrin. The advent of
proton pump inhibitors such as omeprazole has rendered this extreme endocrine
condition fully controllable, but also less easily recognised.
Gastrinomas
may be either sporadic or associated with the autosomal dominantly inherited
multiple endocrine neoplasia (MEN) type I (in which a parathyroid adenoma is
almost invariable). The tumours are most commonly found in the ‘gastrinoma
triangle’ (Passaro) defined by the junction of the cystic duct and common bile
duct superiorly, the junction of the second and third parts of the duodenum
inferiorly, and the junction of the neck and body of the pancreas medially
(essentially the superior mesenteric artery). Many are found in the duodenal
loop, presumably arising in the G cells found in Brunner’s glands. It is
extremely important that the duodenal wall is very carefully inspected endoscopically and also at operation. Very often all that can be
detected is a small nodule which projects into the medial wall of the duodenum.
Even
malignant sporadic gastrinomas may have a very indolent course. The palliative
resection of liver metastases may be beneficial and liver transplantation is
practised in some centres, as for other gut endocrine tumours, with reasonable
long-term results. However, the minority of tumours found to the left of the
superior mesenteric artery (outside the ‘triangle’) seems to have a worse
prognosis, more having liver metastases at presentation. In MEN type I the
tumours may be multiple and the condition is incurable. Even in this situation,
as with sporadic gastrinoma, surgical treatment should be employed to remove any
obvious tumours and associated lymphatic rnetastases as the palliation achieved
may be extremely gratifying.
Duodenal
adenocarcinoma
Although uncommon, this is the commonest site for adenocarcinoma
arising in the small bowel. Most tumours originate in the periampullary region
and commonly arise in preexisting villous adenomas. Patients present with
anaemia due to ulceration of the tumour or obstruction as the polypoid neoplasm
begins to obstruct the duodenum. Direct involvement in the ampulla leads to
obstructive jaundice. Histologically, the lesion is a typical adenocarcinoma
and the rnetastases are commonly to regional lymph nodes and the liver. At
presentation about 70 per cent of the patients have resectable disease and for
those who survive operation the 5-year survival rate is in the region of
20 per cent, this approximately equating to cure. Poor prognostic features in
the resected specimen include regional lymph node metastases, transmural
involvement and perineural invasion. Curative surgical treatment will normally
involve a pancreatrcoduodenectomy (Whipples procedure). Patients with
familial polyposis, which is due to a mutation in the APC gene on
chromosome 5, are predisposed to periampullary cancer which is one of the
most common causes of death in patients who have had their colon removed.
Other
duodenal malignancies are rare.