Duodenal diverticula are found in up to 25 per cent of patients, but rarely cause symptoms. When complications occur, early diagnosis is essential if treatment is to be successful. Duodenal diverticula can be classified into the common extraluminal type and the rare intraluminal type, according to their pathogenesis and clinical presentation.

The first well documented report of a duodenal diverticulum was made by Morgagni in 1762. Although only 100 cases were reported during the next 150 years the introduction of radiological evaluation of the gastrointestinal tract led to duodenal diverticula becoming recognized as a common anatomical abnormality. Earlier this century many patients underwent diverticulectomy for uncertain indications with ambiguous results. Diverticula cause symptoms in only a minority of patients, but their presence should not be ignored in the differential diagnosis of acute abdominal events.

The aetiology of primary duodenal diverticula is unknown. They are in fact pseudodiverticula (because they are not composed of all layers of the bowel wall) and resemble ‘pulsion’ type diverticula seen in other parts of the gastrointestinal tract. These diverticula tend to occur adjacent to the papilla of Vater, perhaps because of a local weakness in the duodenal wall. Embryologically diverticula could result from a locus minoris resistentiae in the musculature, as this is the site of budding and fusion of the pancreatic anlagen in the duodenal fenestrum.

Secondary diverticula are true diverticula, consisting of all layers of the bowel wall. They are caused by adhesions or extraluminal scarring often related to peptic ulcer disease, and are consequently most common in the first part of the duodenum. They account for less than one-fifth of all extraluminal diverticula and do not cause symptoms.

Most duodenal diverticula are solitary and occur in the second portion of the duodenum. The major papilla is usually located close to the rim of the diverticulum; in rare instances, it may lie deep within the diverticulum. Occasionally, diverticula are found around the minor papilla of Santorini. About 10 per cent of diverticula occur in the third or fourth portion of the duodenum. Juxtapapillary duodenal diverticula are more likely to cause symptoms than do diverticula in other parts of the duodenum.

Although extraluminal duodenal diverticula are rare in young patients, their frequency increases with age. There is no sex predilection. At autopsy, primary extraluminal duodenal diverticula occur in up to 22 per cent of individuals, depending on the technique employed and the mean age of the autopsy subjects. The frequency of diverticula in radiologic series is between 0.16 per cent and 5.76 per cent while endoscopic studies show an incidence as high as 23 per cent. Endoscopic and radiological examinations are performed only in patients with symptoms attributed to the upper gastrointestinal tract, and therefore do not necessarily represent the general population. The assumption is that extraluminal duodenal diverticula are rare in those under the age of 30, but may be present in up to 20 per cent of the general population with increasing age.

Ninety per cent of duodenal diverticula are asymptomatic and are detected incidentally during radiological or endoscopic investigation of the upper gastrointestinal tract for an unrelated disease. In 10 per cent of patients, duodenal diverticula are responsible for symptoms; symptomatic diverticula are more common in the elderly. Distension of the diverticulum may cause pain and nausea. Because the symptoms are non-specific they are often attributed to cholelithiasis or gastritis. Some patients may have undergone cholecystectomy and dietary trials without relief. Only after elimination of all other more common causes of upper abdominal pain and nausea are the patient's symptoms attributed to the duodenal diverticulum.

Although complications of duodenal diverticula are rare, they can be devastating. (Table 1) 310. The most common complication is diverticulitis with perforation. Extraluminal diverticula may infarct and rupture if a gallstone or an enterolith obstructs the orifice into the duodenum. Foreign bodies such as fish bones are also prone to perforate the attenuated diverticular wall. However, whether perforation actually results from occlusion of the orifice by an enterolith or from stasis due to the lack of a muscular wall remains unclear. Retroperitoneal abscess and fistula are the most common sequelae of perforation (Fig. 1) 943. Rarely, perforation may lead to a duodenocolic fistula with diarrhoea as the main symptom.

Because diverticula are located in the retroperitoneum, the development of symptoms is insidious, and diagnosis is often delayed. Abdominal or back pain and fever are the most common presenting symptoms. Because of the delay in diagnosis of diverticular perforation, mortality rates can be as high as 50 per cent. Even intraoperatively, the diagnosis may be obscure unless the duodenum is fully mobilized and the retroperitoneum is explored. Intraoperative findings such as bile staining of tissues,retroperitoneal emphysema, and oedema suggest a perforated extraluminal duodenal diverticulum.

The relationship between cholelithiasis, choledocholithiasis and juxtapapillary diverticula is well established. Duodenal diverticula predispose patients to gallstone formation. Even after cholecystectomy, choledocholithiasis is more common in patients with diverticula than in the general population. Juxtapapillary diverticula may compress the distal common bile duct and cause dysfunction or incompetence of the choledocho-duodenal sphincter. Bile cultures from patients with diverticula demonstrate a 70 to 80 per cent incidence of bacterial colonization. Intestinal bacteria are able to split conjugated bilirubin into unconjugated bilirubin and glucuronic acid by the action of the hydrolytic enzyme &bgr;-glucuronidase. Unconjugated bilirubin then combines with calcium in the bile to precipitate and form calculi. Since pigment gallstones are the most common stones in patients with diverticula, a causal relationship is assumed.

Juxtapapillary diverticula are also associated with an increased incidence of pancreatitis. While many of these patients have gallstones, pancreatitis may occur in the absence of biliary lithiasis: this may be due to reflux of duodenal contents through the incompetent ampullary sphincter or even compression of the distal pancreatic duct by the diverticulum.

Haemorrhage occurs if the diverticular wall is ulcerated due to diverticulitis. Bleeding is rarely massive, but patients may present with haematemesis, melaena, and anaemia. Because the bleeding site is within the diverticulum, diagnosis may be difficult. Diverticulectomy is generally required to obtain hemostasis.

Most asymptomatic duodenal diverticula are diagnosed by duodenoscopy; however, upper gastrointestinal series is the diagnostic tool of choice if perforation or a fistulization of a duodenal diverticulum is suspected. Computer assisted tomography may also be helpful in detecting perforation of a duodenal diverticulum. Haemorrhage is best localized by duodenoscopy. Extraluminal diverticula often extend into the pancreas and therefore may be overlooked at autopsy and during surgery.

An uncomplicated duodenal diverticulum does not warrant surgical intervention. In patients with symptoms due to distension of diverticula, relief may be obtained if the patient assumes a position which allows dependent drainage of the diverticulum. The position can be determined by fluoroscopy. Acute obstruction of a diverticulum, which may be the cause of acute pancreatitis or biliary stasis, can be relieved by endoscopic clearance of the diverticulum. If acute obstruction recurs, diverticulectomy should be considered. Some authors have recommended cholecystectomy for silent gallstones in patients with duodenal diverticula to prevent later biliary complications, but there is no firm evidence that this prescription is beneficial for patients who otherwise would not require surgery.

One per cent of patients with diverticula require surgical treatment of a complication. To expose the diverticulum, a Kocher manoeuvre should be performed, as most diverticula are juxtapapillary. Those in the third part of the duodenum, proximal to the superior mesenteric vessels, may be visualized by a wide Kocher manoeuvre and mobilization of the hepatic flexure of the colon. The duodenum distal to the superior mesenteric vessels may be exposed by opening the ligament of Treitz at the base of the mesocolon. The simplest surgical treatment is invagination of the diverticulum into the duodenum without opening the duodenum. This is possible only in small, non-inflamed diverticula. Simple resection of the diverticulum is warranted in almost all cases in which the anatomy permits control of the biliary and pancreatic duct. A transduodenal or combined extraduodenal and transduodenal approach my be necessary to achieve this goal. If a large residual defect remains after resection it should be closed perpendicular to the long axis of the bowel. Primary closure can usually be performed, because the neck of the diverticulum and the duodenal wall are separate from the acute inflammatory process. Resection, however, may be difficult in cases where the diverticulum is buried in the head of the pancreas or the papilla lies deep within the diverticulum. Therefore, in cases in which a direct approach to the diverticulum seems too hazardous, division of the duodenum 2 cm distal to the pylorus with drainage by a Roux-en-Y duodenojejunostomy may be performed. Another method of bypassing a diverticulum is ‘diverticulization’ of the duodenum (antrectomy, vagotomy, choledochostomy, and Billroth II anastomosis). Choledochoduodenostomy or choledochojejunostomy alone do not relieve problems arising from the pancreatic duct and are therefore rarely indicated.

Postoperative deaths and complications are primarily caused by advanced spread of retroperitoneal infection and duodenal fistulae. The only way to prevent extensive spread of retroperitoneal infection is early diagnosis and adequate drainage. Less frequent postoperative complications such as pancreatitis and haemorrhage result from over-aggressive attempts to dissect the diverticulum from the pancreas. A transduodenal approach without the necessity for dissection of the pancreas or Roux-en-Y duodenojejunostomy is often the safest approach.

Intraluminal duodenal diverticulum is a rare entity, less than 100 cases being reported in the world's literature. In contrast to extraluminal duodenal diverticula, however, most patients become symptomatic. There is a high incidence of coexisting congenital gastrointestinal and extraintestinal anomalities.

In the fifth week after conception proliferation of the duodenal epithelium nearly obliterates the lumen of the second to fourth portions of the duodenum. Early in the sixth week vacuoles start to coalesce and form two channels, and by the eighth week both channels are normally consolidated. Intrinsic duodenal obstruction can develop when the duodenum is incompletely recanalized. Duodenal atresia, stenosis, obstructing mucosal diaphragm, or duodenal duplication may develop.

Intraluminal duodenal diverticula arise either from an incomplete duodenal duplication or from a duodenal diaphragm. Incomplete recanalization of one of the two channels may result in a communicating incomplete duplication of the duodenum that ends blindly and is attached to only a small part of the duodenal wall. A duodenal diaphragm may be transformed into a pulsion intraluminal diverticulum with circumferential attachment by the continuous force of the intestinal stream.

Most intraluminal diverticula originate in the second part of the duodenum. As the diverticulum is not innervated it cannot generate peristaltic waves, nor can it cause pain per se. The diverticulum is lined on both sides by epithelium and also contains fibrous tissue with a few smooth muscle cells of the muscularis mucosae. It is poorly vascularized and therefore prone to necrosis if the pressure inside the diverticulum increases. The diverticulum may then slough with no residual defect.

Intraluminal diverticula cause symptoms of partial intestinal obstruction. Unlike duodenal stenosis due to a duodenal diaphragm or to duodenal duplication, which cause symptoms early in life, symptoms occur mainly between the third and fifth decade of life, when the diverticular sac has enlarged sufficiently to obstruct the duodenum. Asymptomatic periods occur when the duodenum is empty and the diverticulum collapses. Postprandial epigastric pain and fullness, vomiting, gastrointestinal bleeding, and weight loss are common. Epigastric tenderness may be present and pancreatitis occurs in 10 to 20 per cent of cases. Rarely, intussusception may occur.

Diagnosis is established either by radiological or endoscopic means. Duodenoscopy is superior to radiological examination in localizing the papilla of Vater and determining the important relationship between the diverticulum and ampulla. The typical radiological appearance is that of a barium coated pouch within the duodenum (Fig. 2) 944. If the sac is not filled with barium (in cases where the opening is very small) it may appear as a pedunculated polyp and the diagnosis may be hard to establish even endoscopically. The exact location has to be determined before surgery since there are no visible changes on the serosal surface of the duodenum and the diverticulum tends to collapse after duodenotomy making palpation quite difficult.

All intraluminal diverticula require treatment unless the patient is too frail to undergo even endoscopic therapy. Without removal of the diverticulum recurrence of symptoms is certain. Curative treatment consists of removal of the diverticulum by laparotomy and duodenotomy or by endoscopy. Care must be taken to avoid injury to the papilla, which is usually located in the immediate vicinity of the diverticulum. If the diverticulum is not circumferentially attached, it can be resected endoscopically with an electrocautery snare. If the diverticulum is attached circumferentially, it can be inverted with the endoscope and then partially resected to create an opening in the blind end measuring at least 1 cm in diameter. When the papilla, common bile duct, or pancreatic duct cannot be clearly identified and intubated for an endoscopic procedure, duodenotomy should be performed. If at the time of duodenotomy the papilla cannot be identified, choledochotomy and placement of a bile duct probe to localize the papilla should be performed prior to resection of the diverticulum. The blind end of the diverticulum has to be identified before resection to rule out complete duplication of the duodenal lumen. Less than 10 bypass operations such as gastrojejunostomy or duodenojejunostomy have been reported to treat intraluminal duodenal diverticula. None of these operations diverted the intestinal stream successfully because diverticulization of the duodenum was not performed and the diverticulum filled again slowly after the operation, leading to recurrence of symptoms.

Incomplete recanalization of the duodenum may result in complete duodenal duplication without connection to the duodenum. Most patients become symptomatic within the first decade of life presenting with nausea and vomiting as signs of partial duodenal obstruction. The radiographic appearance is that of an ovoid, smooth, non-pedunculated filling defect on the medial wall of the duodenum. When the duplication of the duodenum is complete, the common bile duct and pancreatic duct are often involved in the common wall, making complete excision impossible. Treatment in this instance is by generous fenestration of the dividing wall, avoiding the common bile pancreatic duct.

Primary tumours of the duodenum are uncommon. Their peak incidence is between the sixth and eight decade of life, and symptomatic benign and malignant duodenal tumours occur with equal frequency and a near equal sex distribution. The aetiology of duodenal tumours is unknown. The low incidence of these tumours in comparison with adenocarcinoma of the colon and stomach has lead to speculation about the existence of protective factors, such as secretory immunoglobulins, small intestinal hydroxylases that could inactivate potential carcinogens, alkalinity in the duodenum that could prevent formation of potential carcinogens, rapid transit of liquid bowel contents, and lack of bacteria.

Symptoms are related to the tumour location and result from either obstruction of the ampulla, partial duodenal obstruction, or from bleeding caused by the tumour. Nausea and vomiting, pain, jaundice, anaemia, pancreatitis, haematemesis, melaena, palpable mass, duodenal obstruction, weight loss, intussusception, and acute bacterial cholangitis may all occur. Neuroendocrine tumours present with symptoms due to the effects of hormone production.

The diagnosis is often made on upper gastrointestinal series and is confirmed by endoscopy. These two tests provide complementary information: the former defines the precise location and extent of the tumour and detects lesions in the third and fourth portion of the duodenum that are not routinely detected endoscopically. Endoscopy affords the opportunity to delineate the relationship of the tumour to the ampulla and also permits biopsy to be undertaken for tissue diagnosis. Although CT scanning may detect the presence of nodal or liver metastases, it seldom alters management.

Annular pancreas, a relatively common congenital abnormality may be confused with annular carcinoma. It is differentiated by its endoscopic appearance, which shows intact duodenal mucosa, and by computed tomography.

Adenomas are the most common benign tumours in the duodenum and present either as adenomatous polyps, Brunner's gland adenomas, or villous adenomas. The last have a high rate of malignant transformation and are therefore discussed under malignant tumours.

Adenomatous polyps are sessile, nodular, or pedunculated. Although most are asymptomatic, periampullary lesions may cause intermittent jaundice or pancreatitis. Anaemia may also occur secondary to chronic blood loss.

Duodenal adenomatous polyps are common in familial polyposis coli, Peutz–Jegher's syndrome, and Gardner's syndrome, when they may undergo transformation into villous adenomas and adenocarcinomas. However, prophylactic pancreaticoduodenectomy is not recommended. Instead these patients should undergo periodic upper gastrointestinal endoscopies with numerous biopsies and endoscopic removal of suspicious polyps (large lesions, ulcerated or bleeding lesions, lesions with white or firm areas, and lesions found to have tubulovillous components). If an invasive carcinoma is detected radical resection is indicated.

Patients who present with a limited number of adenomatous polyps should undergo endoscopic resection if this is technically feasible. If a suspicious lesion cannot be removed endoscopically, duodenotomy and complete excision is required. If a solitary adenoma is histologically proven to be benign, no further treatment or particular follow-up is necessary. Periodic endoscopy is recommended in patients with multiple polyps.

Brunner's gland adenomas may present as pedunculated polyps, circumscribed nodular hyperplasia, or diffuse nodular hyperplasia. They differ neither in location nor in histology from normal Brunner's glands and produce alkaline mucus. The malignant potential of Brunner's gland adenomas is extremely low. Most patients remain asymptomatic; symptoms which may occur include epigastric pain, bleeding, and obstruction of the duodenum. Endoscopic or local open resection are curative. After surgery patients should receive a treatment with H&sub2;-receptor antagonists if a substantial amount of Brunner's glands have been removed.

Lipomas are smooth submucosal masses with a characteristic yellow appearance on endoscopy. Most remain fairly small, but some may become pedunculated, obstruct the duodenum and cause pain. Intussusception may occur in younger patients. Mucosal erosion may cause bleeding. Enucleation or local excision is sufficient treatment for symptomatic lesions.

Haemangiomas and lymphangiomas are well circumscribed submucosal masses, composed of blood vessels or lymphatic vessels, respectively. Bleeding from haemangiomas may be massive enough to require emergency laparotomy. Both tumours tend to be multifocal. Neurofibromas and schwannomas are poorly circumscribed lesions with wavy, fibrillary elements and are identical to those seen elsewhere in neurofibromatosis. However, duodenal involvement is uncommon in von Recklinghausen's disease and less than 20 per cent of neurofibromas are associated with this syndrome. Bleeding is the most common presenting symptom. Symptomatic lesions should be excised. Leiomyomas are discussed together with leiomyosarcomas because they are not easily differentiated from their malignant counterparts.

In contrast to other gastrointestinal malignancies,up to 25 per cent of duodenal malignant tumours are associated synchronously or metachronously with other primary malignancies. These are most often other adenocarcinomas of the intestinal tract, but breast and prostatic adenocarcinoma, bladder carcinoma, and lymphomas have also been associated with adenocarcinoma of the duodenum. Common aetiological factors may be responsible and since the duodenum is a rare site of tumours it has been postulated that there is an underlying defect in immune surveillance which allows malignant tumours to develop in other locations as well. Close monitoring of all patients with duodenal tumours is therefore warranted (Table 2) 311.

Primary adenocarcinomas of the duodenum are rare, accounting for less than 0.5 per cent of all carcinomas of the gastrointestinal tract. However, the duodenum is the most common site of carcinoma in the small bowel, accounting for 50 per cent of all cases. Virtually all carcinomas of the duodenum are mucin-producing adenocarcinomas originating from glandular epithelium. Macroscopically their appearance ranges from ulcerating and infiltrating to polypoid. Adenocarcinomas most frequently occur in the periampullary region, and approximately 20 per cent of duodenal adenocarcinomas arise in villous adenomas. Rarely, adenocarcinomas are found in a duodenal diverticulum or in patients with non-tropical sprue.

Clinical symptoms of adenocarcinoma of the duodenum depend on the location of the tumour. Fifty per cent of patients present with jaundice and up to 75 per cent of patients have occult blood in their stool. Other common symptoms are frank gastrointestinal haemorrhage and anaemia, abdominal pain, nausea and vomiting, weight loss, pancreatitis, duodenal obstruction, and acute bacterial cholangitis. Although most patients will present with at least one of these symptoms, they are all non-specific and non-diagnostic.

Duodenoscopy is the most sensitive diagnostic procedure because it detects small lesions that may not be visualized by upper gastrointestinal series (Fig. 3) 945 or hypotonic duodenography. If the diagnosis is established endoscopically, however, an upper gastrointestinal series should be performed to search for synchronous jejunal and ileal lesions. It is of utmost importance that the entire duodenum be visualized as the distal duodenum is more often affected than the first portion of the duodenum. One should not be lulled into a false sense of security if endoscopic biopsies fail to reveal carcinoma in a suspicious lesion: the entire lesion should be removed for definitive evaluation. Computed tomography allows assessment of extraluminal spread, involvement of lymph nodes and distant metastasis. Carcinoembryogenic antigen levels tend to be slightly elevated before surgery and should decline after surgery, but they are an unreliable marker for both initial diagnosis and subsequent studies.

The treatment of choice in patients with adenocarcinoma of the duodenum is pancreaticoduodenectomy. Only small tumours in the fourth portion of the duodenum should be treated with distal duodenectomy and duodenojejunostomy. In these cases it may be advisable to place the duodenojejunostomy to the right of the superior mesenteric vessels to avoid placing the anastomosis in the tumour bed. Small tumours of the proximal duodenum in poor risk patients can be resected by extended antrectomy with Billroth II reconstruction. Extreme care should be taken to avoid injuring the accessory pancreatic duct and the common bile duct in these patients.

Both staging and grading have prognostic value. Patients with carcinoma in situ have a near 100 per cent 5-year survival provided that the tumour is completely resected. Few lesions are diagnosed at this early stage, but 30 per cent of lesions are discovered before lymph node involvement occurs. Curative resection in these patients carries a 50 to 70 per cent chance of 5-year survival. In patients with resectable lymph node involvement, however, the 5-year survival is only 20 per cent. Up to half of all patients with adenocarcinoma of the duodenum have unresectable lesions, and only occasionally survive for more than 1 year. Patients with well differentiated Grade I or II carcinomas have a 5-year survival greater than 50 per cent. In contrast Grade III lesions carry a 20 per cent 5-year survival and no patient with Grade IV lesions has yet been reported to survive 5 years. When palliative procedures are necessary, biliary obstruction can be relieved with endoprostheses or surgical bypass. Gastrojejunostomy is generally required to relieve duodenal obstruction. Rarely a palliative resection can be completed to treat ongoing haemorrhage. Adjuvant therapy for adenocarcinoma of the duodenum has been of little value. Chemotherapy has shown no significant effect and the side-effects of radiation to the duodenum outweigh its benefits.

Some 40 to 50 per cent of villous adenomas of the duodenum harbour adenocarcinoma. In contrast to villous adenomas of the colon, size is not related to their malignant potential (Fig. 4) 946. Villous adenomas may be discovered incidentally on endoscopy or may cause biliary obstruction, bleeding, or duodenal obstruction. The majority of tumours are located around the papilla of Vater and therefore present with symptoms earlier than other duodenal tumours. Although duodenoscopy yields excellent results in visualizing the lesion, up to 50 per cent of carcinomas in villous adenomas are missed by endoscopic biopsy. To obtain a definite diagnosis the entire tumour has to be examined histologically after complete removal. The presence of obstructive jaundice implies malignancy in virtually all cases.

In the few cases with a tumour which is small and pedunculated, endoscopic resection is possible. In all other cases duodenotomy is required. Benign villous adenomas can be locally excised (Fig. 5) 947. For lesions histologically proven to be benign and carcinoma in situ removed endoscopically with free margins, close follow-up with frequent duodenoscopy is adequate treatment. Local recurrence occurs in 20 to 50 per cent of patients, making close surveillance mandatory. In centres with experience in performing pancreaticoduodenectomies, where the operative mortality is less than 5 per cent, pancreaticoduodenectomy is preferred to local excision. Since one cannot be certain when invasive adenocarcinoma is present, pancreaticoduodenectomy is the treatment of choice.

Carcinoid tumours are the second most common malignant lesion in the duodenum after adenocarcinomas. They often occur in conjunction with multiple endocrine neoplasia types 1 and 2, von Recklinghausen's neurofibromatosis, and phaeochromocytoma. They may present as adenocarcinoid tumours with glandular and neuroendocrine differentiation. Most tumours measure less than 1 cm in diameter; tumours larger than 1.5 cm are generally malignant and over 90 per cent have metastasized at the time of diagnosis. Few patients ever become symptomatic with carcinoid syndrome from these tumours, and carcinoids are often incidental findings at duodenoscopy or autopsy. However, there is some controversy as to the definition of a carcinoid in the duodenum. For this Section we have considered only serotonin-containing tumours.

Surgical resection is the only therapy for duodenal carcinoid. Local excision is sufficient for benign tumours less than 1.5 cm in diameter; for larger or invasive tumours the rules for resection of adenocarcinoma apply. Trials with radiotherapy and chemotherapy have been disappointing. The prognosis is better than for patients with adenocarcinomas, with overall 5-year survival rates 50 to 75 per cent.

Leiomyomas of the duodenum are the most frequent non-epithelial benign tumours, accounting for about 20 per cent of all benign duodenal tumours. Leiomyomas and leiomyosarcomas occur in all portions of the duodenum. They are well circumscribed, intramural tumours with whorls of smooth muscle closely resembling normal muscularis but usually lacking a true connective tissue capsule. The malignant counterpart, leiomyosarcoma, is not easily distinguished by gross appearance. If the tumour is found to invade adjacent structures or if metastases are found, the malignant nature of the tumour is clear. If the lesion is isolated, only histological evaluation can establish the nature of the tumour. The presence of more than one mitosis per high power field establishes the diagnosis of malignancy.

When symptoms occur, bleeding is the most common complaint. Sarcomas tend to be hypervascular tumours, and haemorrhage, which can occur from central necrosis of the tumour as well as from erosion of the mucosa, may be massive. Large lesions may cause partial duodenal obstruction. Endoscopically, the tumours appear as a smooth, submucosal mass over which the mucosal folds are stretched and effaced. Benign lesions in the distal duodenum can be treated by segmental duodenal resection; if, however, the lesion is close to the papilla, enucleation with preservation or reimplantation of the ampulla is required. If there is any doubt as to the malignancy of the lesion pancreaticoduodenectomy is recommended. Leiomyosarcomas undergo haematogenous spread to the liver and lungs. In selected cases, distant metastases are not a contraindication to surgery as some low grade leiomyosarcomas grow slowly and many patients seem to benefit from aggressive resection of metastatic disease. The role of adjuvant radiotherapy and chemotherapy is under investigation. Generally, sarcomas are much more radiosensitive than adenocarcinomas. Palliative combination chemotherapy with doxorubicin, cyclophosphamide, vincristine, and imidazole carboxamide has yielded response rates over 65 per cent. The long-term prognosis for leiomyosarcomas is intermediate between adenocarcinoma and carcinoid, with 50 per cent of patients surviving 5 years.

Although primary lymphoma of the duodenum is rare, the duodenum may be involved in systemic lymphoma. Only 5 per cent of all lymphomas are primary intestinal lymphoma and less than 10 per cent of these are located in the duodenum. The only way to establish the diagnosis of primary lymphoma is to exclude the presence of the disease in other organs. Most duodenal lymphomas are non-Hodgkin's lymphomas of B-cell origin. Only a few reports exist of Hodgkin's lymphomas or T-cell lymphomas. Involvement of the mesentery and the draining lymph nodes is common.

Lymphomas are difficult to distinguish from carcinoma preoperatively, though they tend to be larger than carcinomas. Often endoscopic biopsies are non-diagnostic as lymphomas arise in the submucosa. In advanced disease (Fig. 6) 948, however, perforation and multiple lesions are more common in lymphomas than in adenocarcinomas of the small bowel.

Lymphomas cause symptoms similar to those of duodenal and pancreatic carcinomas, and their appearance on computed tomography may be confused with pancreatic cancer. Primary lymphoma of the duodenum can be cured by complete resection in only 40 per cent of patients. The role of adjuvant radiotherapy and chemotherapy has not yet been firmly established, but for the more common jejunal and ileal lymphomas a benefit has been shown. In patients who survive 5 years, recurrence is extremely rare and prognosis is excellent. In patients with unresectable lymphoma, radiotherapy and chemotherapy are the primary therapeutic modalities, surgery being used only to treat complications.

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