PART II
Specific Considerations
CHAPTER 33
Pancreas
BASIC SCIENCE QUESTIONS
1. The origin of the inferior pancreaticoduodenal artery is the
A. Gastroduodenal artery
B. Superior mesenteric artery
C. Superior pancreaticoduodenal artery
D. Common hepatic artery
Answer: A
The blood supply to the pancreas comes from multiple branches from the celiac and superior mesenteric arteries (Fig. 33-1). The common hepatic artery gives rise to the gastroduodenal artery before continuing toward the porta hepatis as the proper hepatic artery. The gastroduodenal artery becomes the superior pancreaticoduodenal artery as it passes behind the first portion of the duodenum and branches into the anterior and posterior superior pancreaticoduodenal arteries. As the superior mesenteric artery passes behind the neck of the pancreas, it gives off the inferior pancreaticoduodenal artery at the inferior margin of the neck of the pancreas. This vessel quickly divides into the anterior and posterior inferior pancreaticoduodenal arteries. The superior and inferior pancreaticoduodenal arteries join together within the parenchyma of the anterior and posterior sides of the head of the pancreas along the medial aspect of the C-loop of the duodenum to form arcades that give off numerous branches to the duodenum and head of the pancreas. Therefore, it is impossible to resect the head of the pancreas without devascularizing the duodenum, unless a rim of pancreas containing the pancreaticoduodenal arcade is preserved. (See Schwartz 9th ed., p 1171.)
FIG. 33-1. Arterial supply to the pancreas. Multiple arcades in the head and body of the pancreas provide a rich blood supply. The head of the pancreas cannot be resected without devascularizing the duodenum unless a rim of pancreas containing the pancreaticoduodenal arcade is preserved.
2. Insulin secretion is stimulated by
A. Lysine
B. Somatostatin
C. Amylin
D. Alpha adrenergic stimulation
Answer: A
Oral glucose stimulates the release of enteric hormones such as gastric inhibitory peptide (also known as glucose-dependent insulinotropic polypeptide or GIP), glucagon-like peptide-1 (GLP-1), and CCK, that augment the secretion of insulin, and are therefore referred to as incretins.
Insulin secretion by the β-cell is also influenced by plasma levels of amino acids such as arginine, lysine, leucine, and free fatty acids. Glucagon, GIP, GLP-1, and CCK stimulate insulin release, while somatostatin, amylin, and pancreastatin inhibit insulin release. Cholinergic fibers and beta sympathetic fibers stimulate insulin release, while alpha sympathetic fibers inhibit insulin secretion. (See Schwartz 9th ed., p 1175.)
3. The highest concentration of PP (pancreatic polypeptide) cells is found in the
A. Head of the pancreas
B. Body of the pancreas
C. Tail of the pancreas
D. None of the above—they are equally distributed across the pancreas
Answer: A
The β- and δ-cells are evenly distributed throughout the pancreas, but islets in the head and uncinate process (ventral anlage) have a higher percentage of PP cells and fewer α-cells, whereas islets in the body and tail (dorsal anlage) contain the majority of α-cells and few PP cells. This is clinically significant because pancreatoduodenectomy removes 95% of the PP cells in the pancreas. This may partially explain the higher incidence of glucose intolerance after the Whipple procedure than after distal pancreatectomy. In addition, chronic pancreatitis, which disproportionately affects the pancreatic head, is associated with PP deficiency and pancreatogenic diabetes. (See Schwartz 9th ed., p 1177.)
4. Which of the following pancreatic enzymes is secreted in an active form?
A. Amylase
B. Chymotrypsinogen
C. Tyrpsinogen
D. Pepsin
Answer: A
Pancreatic amylase is secreted in its active form and completes the digestive process already begun by salivary amylase. Amylase is the only pancreatic enzyme secreted in its active form, and it hydrolyzes starch and glycogen to glucose, maltose, maltotriose, and dextrins.
The proteolytic enzymes are secreted as proenzymes that require activation. Trypsinogen is converted to its active form, trypsin, by another enzyme, enterokinase, which is produced by the duodenal mucosal cells. Trypsin, in turn, activates the other proteolytic enzymes. (See Schwartz 9th ed., p 1174.)
5. Sympathetic stimulation of the pancreas results in
A. Stimulation of endocrine and exocrine secretion
B. Inhibition of endocrine and exocrine secretion
C. Stimulation of endocrine and inhibition of exocrine secretion
D. Inhibition of endocrine and stimulation of exocrine secretion
Answer: B
The pancreas is innervated by the sympathetic and parasympathetic nervous systems. The acinar cells responsible for exocrine secretion, the islet cells responsible for endocrine secretion, and the islet vasculature are innervated by both systems. The parasympathetic system stimulates endocrine and exocrine secretion and the sympathetic system inhibits secretion. (See Schwartz 9th ed., p 1173.)
6. Somatostatin-28, one of the two active forms of somatostatin present in the human body, selectively binds to
A. SSTR1
B. SSTR3
C. SSTR5
D. None of the above
Answer: C
One gene encodes for a common precursor that is differentially processed to generate tissue-specific amounts of two bioactive products, somatostatin-14 and somatostatin-28. These peptides inhibit endocrine and exocrine secretion and affect neurotransmission, GI and biliary motility, intestinal absorption, vascular tone, and cell proliferation. Five different somatostatin receptors (SSTRs) have been cloned and the biologic properties of each are being unraveled. All five are G-protein-coupled receptors with seven highly conserved transmembrane domains and unique amino and carboxy termini. Phosphorylation sites located within the second and third intracellular loops and in the cytoplasmic C-terminal segment are thought to mediate receptor regulation. Although the naturally occurring peptides bind to all five receptors, somatostatin-28 is relatively selective for SSTR5. (See Schwartz 9th ed., p 1176.)
7. The most common gene mutation found in pancreatic cancer is
A. HER2/neu
B. K-ras
C. p53
D. Smad 4
Answer: B
Pancreatic carcinogenesis probably involves multiple mutations that are inherited and acquired throughout aging. The K-ras on-cogene is currently thought to be the most commonly mutated gene in pancreatic cancer, with approximately 90% of tumors having a mutation. This prevalent mutation is present in precursor lesions and is therefore thought to occur early and be essential to pancreatic cancer development. K-ras mutations can be detected in DNA from serum, stool, pancreatic juice, and tissue aspirates of patients with pancreatic cancer, suggesting that the presence of this mutation may provide the basis for diagnostic testing in select individuals. The HER2/neu oncogene, homologous to the epidermal growth factor receptor (EGFr), is overex-pressed in pancreatic cancers. This receptor is involved in signal transduction pathways that lead to cellular proliferation. Multiple tumor-suppressor genes are deleted and/or mutated in pancreatic cancer, and include p53, p16, and DPC4 (Smad 4), and in a minority of cases, BRCA2. Most pancreatic cancers have three or more of the above mutations. (See Schwartz 9th ed., p 1220.)
8. Pancreatic delta cells produce
A. Somatostatin
B. Ghrelin
C. Pancreatic polypeptide (PP)
D. Glucagon
Answer: A
There are nearly 1 million islets of Langerhans in the normal adult pancreas. They vary greatly in size from 40 to 900 μm. Larger islets are located closer to the major arterioles and smaller islets are embedded more deeply in the parenchyma of the pancreas. Most islets contain 3000 to 4000 cells of five major types: alpha cells that secrete glucagon, β-cells that secrete insulin, delta cells that secrete somatostatin, epsilon cells that secrete ghrelin, and PP cells that secrete PP (Table 33-1). (See Schwartz 9th ed., p 1175.)
TABLE 33-1 Pancreatic islet peptide products
9. Pancreatic acinar cells secrete
A. Lipases
B. Amylase
C. Proteases
D. All of the above
Answer: D
The acinar cells secrete amylase, proteases, and lipases, enzymes responsible for the digestion of all three food types: carbohydrate, protein, and fat. The acinar cells are pyramid-shaped, with their apices facing the lumen of the acinus. Near the apex of each cell are numerous enzyme-containing zymogen granules that fuse with the apical cell membrane. Unlike the endocrine pancreas, where islet cells specialize in the secretion of one hormone type, individual acinar cells secrete all types of enzymes. However, the ratio of the different enzymes released is adjusted to the composition of digested food through nonparallel regulation of secretion. (See Schwartz 9th ed., p 1174, and Table 33-2.)
TABLE 33-2 Pancreatic enzymes
10. Which of the following is the primary stimulus for secretion of bicarbonate by the pancreas?
A. CCK
B. Gastrin
C. Acetylcholine
D. Secretin
Answer: D
The hormone secretin is released from cells in the duodenal mucosa in response to acidic chyme passing through the pylorus into the duodenum. Secretin is the major stimulant for bicarbonate secretion, which buffers the acidic fluid entering the duodenum from the stomach. CCK also stimulates bicarbonate secretion, but to a much lesser extent than secretin. CCK potentiates secretin-stimulated bicarbonate secretion. Gastrin and acetylcholine, both stimulants of gastric acid secretion, are also weak stimulants of pancreatic bicarbonate secretion. (See Schwartz 9th ed., p 1175.)
11. Approximately what percentage of the population has a replaced right hepatic artery?
A. 2%
B. 5%
C. 10%
D. 15%
Answer: D
Variations in the arterial anatomy occur in one out of five patients. The right hepatic artery, common hepatic artery, or gastroduodenal arteries can arise from the superior mesenteric artery. In 15 to 20% of patients, the right hepatic artery will arise from the superior mesenteric artery and travel upwards toward the liver along the posterior aspect of the head of the pancreas (referred to as a replaced right hepatic artery). It is important to look for this variation on preoperative computed tomographic (CT) scans and in the operating room so the replaced hepatic artery is recognized and injury is avoided. (See Schwartz 9th ed., p 1171.)
12. The veins of the head of the pancreas drain into the
A. Anterior surface of the portal vein
B. Posterolateral surface of the portal vein
C. Right renal vein
D. Inferior vena cava
Answer: B
Venous branches draining the pancreatic head and uncinate process enter along the right lateral and posterior sides of the portal vein. There are usually no anterior venous tributaries, and a plane can usually be developed between the neck of the pancreas and the portal and superior mesenteric veins during pancreatic resection, unless the tumor is invading the vein anteriorly. (See Schwartz 9th ed., p 1171, and Fig. 33-2.)
FIG. 33-2. Venous drainage from the pancreas. The venous drainage of the pancreas follows a pattern similar to the arterial supply, with the veins usually superficial to the arteries. Anterior traction on the transverse colon can tear fragile branches along the inferior border of the pancreas, which then retract into the parenchyma of the pancreas. Venous branches draining the pancreatic head and uncinate process enter along the right lateral and posterior sides of the portal vein. There are usually no anterior venous tributaries, and a plane can usually be developed between the neck of the pancreas and the portal and superior mesenteric veins.
CLINICAL QUESTIONS
1. Which of the following is NOT a cause of elevated gastrin?
A. Proton pump inhibitors
B. Gastric outlet obstruction
C. Chronic pancreatitis
D. Pernicious anemia
Answer: C
The diagnosis of [Zollinger-Ellison syndrome (due to excess gastrin secretion by a gastrinoma)] is made by measuring the serum gastrin level. It is important that patients stop taking proton pump inhibitors for this test. In most patients with gastrinomas, the level is >1000 pg/mL. Gastrin levels can be elevated in conditions other than ZES. Common causes of hypergastrinemia include pernicious anemia, treatment with proton pump inhibitors, renal failure, G-cell hyperplasia, atrophic gastritis, retained or excluded antrum, and gastric outlet obstruction. In equivocal cases, when the gastrin level is not markedly elevated, a secretin stimulation test is helpful. (See Schwartz 9th ed., p 1218.)
2. Which of the following should be ordered in a patient with a gastrinoma?
A. Serum vitamin D level
B. Serum calcium
C. Serum B12 level
D. Stool occult blood
Answer: B
It is important to rule out MEN1 syndrome by checking serum calcium levels before surgery because resection of the gastrinoma(s) in these patients rarely results in normalization of serum gastrin concentrations or a prolongation of survival. Only one fourth of gastrinomas occur in association with the MEN1 syndrome. One half of patients with gastrinomas will have solitary tumors while the remainder will have multiple gastrinomas. Multiple tumors are more common in patients with MEN1 syndrome. Aggressive surgical treatment is justified in patients with sporadic gastrinomas. If patients have MEN1 syndrome, the parathyroid hyperplasia is addressed with total parathyroidectomy and implantation of parathyroid tissue in the forearm. (See Schwartz 9th ed., p 1219.)
3. Preservation of the pylorus during the Whipple procedure may
A. Increase the incidence of marginal ulcers
B. Maintain normal gastric hormone release
C. Impair gastric emptying
D. Improve quality of life
Answer: B
The preservation of the pylorus has several theoretical advantages, including prevention of reflux of pancreaticobiliary secretions into the stomach, decreased incidence of marginal ulceration, normal gastric acid secretion and hormone release, and improved gastric function. Patients with pylorus-preserving resections have appeared to regain weight better than historic controls in some studies. Return of gastric emptying in the immediate postoperative period may take longer after the pylorus-preserving operation, and it is controversial whether there is any significant improvement in long-term quality of life with pyloric preservation. (See Schwartz 9th ed., p 1226.)
4. Which of the following drugs has been shown to improve outcome in patients with mild pancreatitis?
A. H2 blockers
B. Somatostatin
C. Glucagon
D. None of the above
Answer: D
Pancreatitis is classified as mild when the patient has no systemic complications, low APACHE-II scores and Ransons signsand sustained clinical improvement and when a CT scan rules out necrotizing pancreatitis. The treatment then is mostly supportive and has the important aim of resting the pancreas through restriction of oral food and fluids. Nasogastric suction and H2-blockers have routinely been used in this connection, based on the reasoning that even the smallest amount of gastric acid reaching the duodenum could stimulate pancreatic secretion. However, these measures are of little value. The following secretion-inhibiting drugs have also been tried without notable success: atropine, calcitonin, somatostatin, glucagon, and fluorouracil. (See Schwartz 9th ed., p 1184, and Fig. 33-3.)
FIG. 33-3. Algorithm for managing acute pancreatitis. CRP = C-reactive protein; CT = computed tomography; FNA = fine-needle aspiration; ICU = intensive care unit; IL-6 = interleukin 6; LDH = lactate dehydrogenase; TAP = trypsinogen activation peptide.
5. Which of the following procedures is the best treatment for a 1.5-cm insulinoma located in the mid pancreas?
A. Enucleation
B. Wedge resection
C. Distal pancreatectomy
D. Duodenal sparing total pancreatectomy
Answer: A
Unlike most endocrine pancreatic tumors, the majority (90%) of insulinomas are benign and solitary, and only 10% are malignant. They are typically cured by simple enucleation. However, tumors located close to the main pancreatic duct and large (>2 cm) tumors may require a distal pancreatectomy or pancreaticoduodenectomy. Intraoperative US is useful to determine the tumor’s relation to the main pancreatic duct and guides intraoperative decision making. Enucleation of solitary insulinomas and distal pancreatectomy for insulinoma can sometimes be performed using a minimally invasive technique. (See Schwartz 9th ed., p 1218.)
6. The most common type of pancreatic cancer is
A. Ductal adenocarcinoma
B. Adenosquamous carcinoma
C. Acinar cell carcinoma
D. Squamous cell carcinoma
Answer: A
In addition to ductal adenocarcinoma, which makes up about 75% of nonendocrine cancers of the pancreas, there are a variety of less common types of pancreatic cancer. Adenosquamous carcinoma is a variant that has both glandular and squamous differentiation. The biologic behavior of this lesion is unfortunately no better than the typical ductal adenocarcinoma. Acinar cell carcinoma is an uncommon type of pancreatic cancer that usually presents as a large tumor, often 10 cm in diameter or more, but the prognosis of patients with these tumors may be better than with ductal cancer. (See Schwartz 9thed., p 1220.)
7. Which of the following techniques decreases the risk of pancreatic anastomotic leak in the Whipple procedure?
A. End-to-side anastomosis
B. Side-to-side anastomosis
C. Duct to mucosa sutures
D. None of the above
Answer: D
Techniques for the pancreaticojejunostomy include end-to-side or end-to-end and duct-to-mucosa sutures or invagination. Pancreaticogastrostomy has also been investigated. Some surgeons use stents, glue to seal the anastomosis, or octreotide to decrease pancreatic secretions. No matter what combination of these techniques is used, the pancreatic leakage rate is always about 10%. Therefore, the choice of techniques depends more on the surgeon’s personal experience. (See Schwartz 9th ed., p 1227.)
8. Which of the following is often adjacent to the inferior border of a pancreatic pseudocyst?
A. Posterior wall of the stomach
B. Splenic vein
C. Transverse mesocolon
D. Left kidney
Answer: C
Pancreatic pseudocysts commonly develop in the area of the lesser sac, and the posterior aspect of the stomach can form the anterior wall of the pseudocyst, allowing drainage into the stomach. The base of the transverse mesocolon attaches to the inferior margin of the body and tail of the pancreas. The transverse mesocolon often forms the inferior wall of pancreatic pseudocysts or inflammatory processes allowing surgical drainage through the transverse mesocolon. (See Schwartz 9th ed., p 1168.)
9. Which of the following is the most sensitive imaging study to identify and localize a gastrinoma?
A. CT scan
B. MRI
C. PET scan
D. Octreotide scintigraphy
Answer: D
In 70 to 90% of patients, the primary gastrinoma is found in Passaro’s triangle, an area defined by a triangle with points located at the junction of the cystic duct and common bile duct, the second and third portion of the duodenum, and the neck and body of the pancreas. However, because gastrinomas can be found almost anywhere, whole-body imaging is required. The test of choice is SSTR (octreotide) scintigraphy in combination with CT. The octreotide scan is more sensitive than CT, locating about 85% of gastrinomas and detecting tumors 1 cm. With the octreotide scan, the need for tedious and technically demanding selective angiography and measurement of gastrin gradients has declined. EUS is another new modality that assists in the preoperative localization of gastrinomas. It is particularly helpful in localizing tumors in the pancreatic head or duodenal wall, where gastrinomas are usually 1 cm in size. A combination of octreotide scan and EUS detects >90% of gastrinomas. (See Schwartz 9th ed., p 1218.)
10. Which of the following is suggestive of malignancy in a cystic lesion of the pancreas?
A. Elevated LDH in the cyst fluid
B. Cyst wall >3 mm in thickness
C. Thick, mucinous fluid in the cyst cavity
D. Hemorrhagic fluid in the cyst cavity
Answer: C
A cystic neoplasm needs to be considered when a patient presents with a fluid-containing pancreatic lesion. Cystic neoplasms of the pancreas may be more frequent than previously recognized and are being identified with increasing frequency as the use of abdominal CT scanning has increased. Most of these lesions are benign or slow growing, and the prognosis is significantly better than with pancreatic adenocarcinoma. However, some of these neoplasms slowly undergo malignant transformation and thus represent an opportunity for surgical cure, which is exceedingly uncommon in the setting of pancreatic adenocarcinoma. Cysts that contain thick fluid with mucin, elevated carcinoembryonic antigen (CEA), or atypical cells must be treated as potentially malignant (Fig. 33-4). (See Schwartz 9th ed., p 1232.)
FIG. 33-4. Algorithm for management of pancreatic cystic neoplasms. CEA = carcinoembryonic antigen; CT = computed tomography; ERCP = endoscopic retrograde cholangiopancreatography; EUS = endoscopic ultrasound; FNA = fine-needle aspiration; Hx = history; IPMN = intraductal papillary mucinous neoplasm of the pancreas; MCN = mucinous cystic neoplasm; MRCP = magnetic resonance cholangiopancreatography.
11. The most common location for a VIPoma is
A. Head of the pancreas
B. Tail of the pancreas
C. Passaro’s triangle
D. Duodenal wall
Answer: B
In 1958, Verner and Morrison first described the syndrome associated with a pancreatic neoplasm secreting VIP. The classic clinical syndrome associated with this pancreatic endocrine neoplasm consists of severe intermittent watery diarrhea leading to dehydration, and weakness from fluid and electrolyte losses. Large amounts of potassium are lost in the stool. The vasoactive intestinal peptidesecreting tumor (VIPoma) syndrome is also called the WDHA syndrome due to the presence of watery diarrhea, hypokalemia, and achlorhydria. The massive (5 L/d) and episodic nature of the diarrhea associated with the appropriate electrolyte abnormalities should raise suspicion of the diagnosis. Serum VIP levels must be measured on multiple occasions because the excess secretion of VIP is episodic, and single measurements might be normal and misleading. A CT scan localizes most VIPomas, although as with all islet cell tumors, EUS is the most sensitive imaging method. Electrolyte and fluid balance is sometimes difficult to correct preoperatively and must be pursued aggressively. Somatostatin analogues are helpful in controlling the diarrhea and allowing replacement of fluid and electrolytes. VIPomas are more commonly located in the distal pancreas and most have spread outside the pancreas. (See Schwartz 9th ed., p 1219.)
12. Failure to inhibit activation of which of the following enzymes can cause familial pancreatitis?
A. Trypsinogen
B. Pepsinogen
C. Chymotrypsinogen
D. Elastase
Answer: A
Trypsinogen activation within the pancreas is prevented by the presence of inhibitors that are also secreted by the acinar cells. A failure to express a normal trypsinogen inhibitor, pancreatic secretory trypsin inhibitor (PSTI) or SPINK1, is a cause of familial pancreatitis. Trypsinogen is expressed in several isoforms, and a missense mutation on the cationic trypsinogen, or PRSS1, results in premature, intrapancreatic activation of trypsinogen. This accounts for about two-thirds of cases of hereditary pancreatitis. (See Schwartz 9th ed., p 1174.)
13. Which of the following is NOT a recognized cause of pancreatitis?
A. Pancreas divisum
B. Hypermagnesemia
C. Venom
D. Hypercalcemia
Answer: B
The etiology of acute pancreatitis is a complex subject because many different factors have been implicated in the causation of this disease, and sometimes there are no identifiable causes (Table 33-3). Two factors, biliary tract stone disease and alcoholism, account for 80 to 90% of the cases. The remaining 10 to 20% is accounted for either by idiopathic disease or by a variety of miscellaneous causes including trauma, surgery, drugs, heredity, infection and toxins. (See Schwartz 9th ed., p 1178.)
TABLE 33-3 Etiologies of acute pancreatitis
|
Alcohol Biliary tract disease Hyperlipidemia Hereditary Hypercalcemia Trauma External Surgical Endoscopic retrograde cholangiopancreatography Ischemia Hypoperfusion Atheroembolic Vasculitis Pancreatic duct obstruction Neoplasms Pancreas divisum Ampullary and duodenal lesions Infections Venom Drugs Idiopathic Source: Reproduced with permission from Yeo CJ, Cameron JL: Exocrine pancreas, in Townsend CM et al (eds): Sabiston’s Textbook of Surgery. Philadelphia: Saunders, 2000, p 1117. Copyright © Elsevier. |
14. Which of the following CT findings is NOT considered a sign that a pancreatic tumor is unresectable?
A. Enlarged lymph nodes outside the boundary of resection
B. Ascites
C. Invasion of the superior mesenteric vein
D. Invasion of the superior mesenteric artery
Answer: C
CT findings that indicate a tumor is unresectable include invasion of the hepatic or superior mesenteric artery, enlarged lymph nodes outside the boundaries of resection, ascites, and distant metastases (e.g., liver). Invasion of the superior mesenteric vein or portal vein is not in itself a contraindication to resection as long as the veins are patent. In contrast, CT scanning is less accurate in predicting resectable disease. CT scanning will miss small liver metastases, and predicting arterial involvement is sometimes difficult. (See Schwartz 9th ed., p 1222.)
15. Serum amylase rises at the onset of pancreatitis and remains elevated for
A. 24 hours
B. 48 hours
C. 3-5 days
D. 7-10 days
Answer: C
Serum amylase concentration increases almost immediately with the onset of disease and peaks within several hours. It remains elevated for 3 to 5 days before returning to normal. There is no significant correlation between the magnitude of serum amylase elevation and severity of pancreatitis; in fact, a milder form of acute pancreatitis is often associated with higher levels of serum amylase as compared with that in a more severe form of the disease.
Other pancreatic enzymes also have been evaluated to improve the diagnostic accuracy of serum measurements. Specificity of these markers ranges from 77 to 96%, the highest being for lipase. Because serum levels of lipase remain elevated for a longer time than total or p-amylase, it is the serum indicator of highest probability of the disease. (See Schwartz 9th ed., p 1182.)
16. Which of the following is NOT a risk factor for pancreatic cancer?
A. Age >60
B. African American race
C. Smoking
D. Female gender
Answer: D
Pancreatic cancer is more common in the elderly with most patients being >60 years old. Pancreatic cancer is more common in African Americans and slightly more common in men than women. The risk of developing pancreatic cancer is two to three times higher if a parent or sibling had the disease. Another risk factor that is consistently linked to pancreatic cancer is cigarette smoking. Smoking increases the risk of developing pancreatic cancer by at least twofold due to the carcinogens in cigarette smoke. Coffee and alcohol consumption have been investigated as possible risk factors, but the data are inconsistent. As in other GI cancers, diets high in fat and low in fiber, fruits, and vegetables are thought to be associated with an increased risk of pancreatic cancer. (See Schwartz 9th ed., p 1220.)
17. The “fish eye” sign, or mucin extruding from the ampulla of Vater during ERCP, is virtually pathognomonic for
A. Cystadenoma of the pancreas
B. Mucinous cystadenoma
C. Intraductal papillary mucinous neoplasm
D. Mucinous adenocarcinoma of the pancreas
Answer: C
At ERCP, mucin can be seen extruding from the ampulla of Vater, a so-called fish-eye lesion, that is virtually diagnostic of IPMN.
Intraductal papillary mucinous neoplasms (IPMNs) usually occur within the head of the pancreas and arise within the pancreatic ducts. The ductal epithelium forms a papillary projection into the duct, and mucin production causes intraluminal cystic dilation of the pancreatic ducts. Patients are usually in their seventh to eighth decade of life and present with abdominal pain or recurrent pancreatitis, thought to be caused by obstruction of the pancreatic duct by thick mucin. Some patients (5 to 10%) have steatorrhea, diabetes, and weight loss secondary to pancreatic insufficiency. (See Schwartz 9th ed., p 1234.)
18. Which of the following analgesic drugs should NOT be used in a patient with pancreatitis?
A. Meperidine
B. Morphine
C. Buprenorphine
D. Pentazocine
Answer: B
The severe pain of acute pancreatitis prevents the patient from resting, and results in ongoing cholinergic discharge, which stimulates gastric and pancreatic secretion. Therefore, pain management is of great importance. Administration of buprenorphine, pentazocine, procaine hydrochloride, and meperidine are all of value in controlling abdominal pain. Morphine is to be avoided, due to its potential to cause sphincter of Oddi spasm. (See Schwartz 9th ed., p 1184.)
19. The most common complication of chronic pancreatitis is
A. Hemorrhage
B. Necrotizing infection
C. Pseudocyst
D. Duodenal obstruction
Answer: C
A chronic collection of pancreatic fluid surrounded by a nonepithelialized wall of granulation tissue and fibrosis is referred to as a pseudocyst. Pseudocysts occur in up to 10% of patients with acute pancreatitis, and in 20 to 38% of patients with chronic pancreatitis, and thus, they comprise the most common complication of chronic pancreatitis. (See Schwartz 9th ed., p 1200, and Table 33-4.)
TABLE 33-4 Complications of chronic pancreatitis
|
Intrapancreatic complications Pseudocysts Duodenal or gastric obstruction Thrombosis of splenic vein Abscess Perforation Erosion into visceral artery Inflammatory mass in head of pancreas Bile duct stenosis Portal vein thrombosis Duodenal obstruction Duct strictures and/or stones Ductal hypertension and dilatation Pancreatic carcinoma Extrapancreatic complications Pancreatic duct leak with ascites or fistula Pseudocyst extension beyond lesser sac into mediastinum, retroperitoneum, lateral pericolic spaces, pelvis, or adjacent viscera |
20. Appropriate management of a patient with an asymptomatic 3-cm cystadenoma of the tail of the pancreas is
A. Observation and serial CT scans
B. Percutaneous cyst aspiration and sclerosis
C. Enucleation
D. Distal pancreatectomy
Answer: A
Serous cystadenomas are essentially considered benign tumors without malignant potential. Serous cystadenocarcinoma has been reported very rarely (1%). Therefore, malignant potential should not be used as an argument for surgical resection, and the majority of these lesions can be safely observed in the absence of symptoms due to mass effect or rapid growth.
All regions of the pancreas are affected, with half of cystadenomas found in the head/uncinate process, and half in the neck, body, or tail of the pancreas. They have a spongy appearance, and multiple small cysts (microcystic) are more common than larger cysts (macrocystic or oligocystic). These lesions contain thin serous fluid that does not stain positive for mucin and is low in CEA (200 ng/mL). Typical imaging characteristics include a well-circumscribed cystic mass, small septations, fluid close to water density, and sometimes, a central scar with calcification. If a conservative management is adopted, it is important to be sure of the diagnosis. EUS-FNA should yield nonviscous fluid with low CEA and amylase levels, and if cells are obtained, which is rare, they are cuboidal and have a clear cytoplasm. (See Schwartz 9th ed., p 1233.)
21. Which of the following is NOT an indication for diagnostic laparoscopy to determine respectability in a patient with pancreatic cancer?
A. CT demonstrates respectable disease
B. CA19-9 is high
C. Tumor size 2 cm
D. Ascites
Answer: C
Diagnostic laparoscopy is possibly best applied to patients with pancreatic cancer on a selective basis. Diagnostic laparoscopy will have a higher yield in patients with large tumors (>4 cm), tumors located in the body or tail, patients with equivocal findings of metastasis or CT scan, ascites, high CA 19-9, or marked weight loss. (See Schwartz 9th ed, pp 1223, 1224 and Fig. 33-5.)
FIG. 33-5. Diagnostic and treatment algorithm for pancreatic cancer. If computed tomography (CT) scan demonstrates a potentially resectable tumor, patients are offered participation in a clinical trial after histologic confirmation by CT or endoscopic ultrasound (EUS)-guided biopsy. If CT scan demonstrates resectable disease, diagnostic laparoscopy is used selectively in patients with tumors in the body/tail, equivocal findings of metastasis or CT scan, ascites, high CA19-9, or marked weight loss. Patients also have diagnostic laparoscopy if they elect to participate in a neoadjuvant clinical trial. In cases where no mass is demonstrated on CT scan, but suspicion of cancer remains, EUS or endoscopic retrograde cholangiopancreatography (ERCP) with brushings are performed, and the CT may be repeated after an interval of observation.
22. Which of the following is the preferred treatment for a persistent pseudocyst after traumatic injury to the pancreas?
A. External drainage
B. Endoscopic stenting of the pancreatic duct
C. Cystgastrostomy
D. Cystjejunostomy
Answer: B
Because pseudocysts often communicate with the pancreatic ductal system, two newer approaches to pseudocyst management are based on main duct drainage, rather than pseudo-cyst drainage per se. Transpapillary stents inserted at the time of ERCP may be directed into a pseudocyst through the ductal communication itself, or can be left across the area of suspected duct leakage to facilitate decompression and cyst drainage, analogous to the use of common bile duct stents in the setting of a cystic duct leak. In a surgical series of patients with chronic pancreatitis, ductal dilatation, and a coexisting pseudocyst, Nealon and Walser showed that duct drainage alone, without a separate cystoenteric anastomosis, was as successful as a combined drainage procedure. Furthermore, the ‘duct drainage only’ group enjoyed a shorter hospital stay and fewer complications than the group who underwent a separate cystoenterostomy. These observations suggest that transductal drainage may be a safe and effective approach to the management of pseudocystic disease. The endoscopic approach seems logical in the treatment of postoperative or post-traumatic pseudocysts when duct disruption is documented or in those patients with pseudocysts that communicate with the duct. (See Schwartz 9th ed., p 1202.)
23. The most common endocrine tumor of the pancreas is
A. Gastrinoma
B. Glucagonoma
C. Insulinoma
D. Somatostatinoma
Answer: C
Insulinomas are the most common pancreatic endocrine neoplasms and present with a typical clinical syndrome known as Whipple’s triad. The triad consists of symptomatic fasting hypoglycemia, a documented serum glucose level 50 mg/dL, and relief of symptoms with the administration of glucose. (See Schwartz 9th ed., p 1217.)
24. Which of the following is one of Ranson’s criteria determined during the initial assessment of a patient with pancreatitis?
A. Serum calcium 8 mg/dL
B. Serum LDH >350 IU/dL
C. Blood glucose >120 mg/dL
D. Serum AST >150 U/dL
Answer: B
In 1974, Ranson identified a series of prognostic signs for early identification of patients with severe pancreatitis. Out of these 11 objective parameters, five are measured at the time of admission, whereas the remaining six are measured within 48 hours of admission (Table 33-5). Morbidity and mortality of the disease are directly related to the number of signs present. If the number of positive Ranson signs is less than two, the mortality is generally zero; with three to five positive signs, mortality is increased to 10 to 20%. The mortality rate increases to >50% when there are more than seven positive Ranson signs. (See Schwartz 9th ed., p 1183.)
TABLE 33-5 Ranson’s prognostic signs of pancreatitis
25. Which of the following is the most sensitive diagnostic test for chronic pancreatitis?
A. Serum amylase
B. Serum lipase
C. Postprandial pancreatic polypeptide hormone
D. Oral glucose tolerance test
Answer: C
The direct measurement of pancreatic enzymes (e.g., lipase and amylase) by blood test is highly sensitive and fairly specific in acute pancreatitis but is seldom helpful in the diagnosis of chronic pancreatitis. The pancreatic endocrine product that correlates most strongly with chronic pancreatitis is the PP response to a test meal. Severe chronic pancreatitis is associated with a blunted or absent PP response to feeding but, as with many other tests, a normal PP response does not rule out the presence of early disease. (See Schwartz 9th ed., p 1198.)
26. At the time of laparotomy, which of the following is a contraindication to proceeding with a Whipple resection?
A. Duodenal invasion
B. Pyloric invasion
C. Clinically positive hilar lymph nodes
D. Clinically positive peripancreatic nodes
Answer: C
Hepatic hilar node involvement is a contraindication to proceeding with the Whipple procedure (Table 33-6). Enlarged or firm lymph nodes that can be swept down toward the head of the pancreas with the specimen do not preclude resection. Invasion of the duodenum or pylorus is not a contraindication to resection. (See Schwartz 9th ed., p 1225.)
TABLE 33-6 Findings at exploration
|
Findings contraindicating resection Liver metastases (any size) Celiac lymph node involvement Peritoneal implants Hepatic hilar lymph node involvement Findings not contraindicating resection Invasion at duodenum or distal stomach Involved peripancreatic lymph nodes Involved lymph nodes along the porta hepatis that can be swept down with the specimen |
27. Patients with gallstone pancreatitis should undergo cholecystectomy
A. Emergently (within the first 12-24 hours of admission)
B. Within 48-72 hours of admission
C. Following ERCP
D. 4-6 weeks after resolution of symptoms
Answer: B
General consensus favors either urgent intervention (cholecystectomy) within the first 48 to 72 hours of admission, or briefly delayed intervention (after 72 hours, but during the initial hospitalization) to give an inflamed pancreas time to recover. Cholecystectomy and operative common duct clearance is probably the best treatment for otherwise healthy patients with obstructive pancreatitis. However, patients who are at high risk for surgical intervention are best treated by endoscopic sphincterotomy, with clearance of stones by ERCP. In the case of acute biliary pancreatitis in which chemical studies suggest that the obstruction persists after 24 hours of observation, emergency endoscopic sphincterotomy and stone extraction is indicated. Routine ERCP for examination of the bile duct is discouraged in cases of biliary pancreatitis, as the probability of finding residual stones is low, and the risk of ERCP-induced pancreatitis is significant. (See Schwartz 9th ed., p 1186.)
28. What percentage of patients who consume 100 to 150 g (7-10 drinks) of alcohol per day will develop pancreatitis?
A. 1-3%
B. 10-15%
C. 20-30%
D. 50-65%
Answer: B
The nature of alcohol consumed (i.e., beer, wine, or hard liquor) is less significant than a daily intake of between 100 and 150 g of ethanol. Between 10 and 15% of individuals with this degree of alcohol intake go on to develop pancreatitis, while a similar proportion develop cirrhosis of the liver. (See Schwartz 9th ed., p 1179.)
29. The most common cause of chronic pancreatitis is
A. Alcohol consumption
B. Hypertriglyceridemia
C. Autoimmune pancreatitis
D. Hereditary pancreatitis
Answer: A
Worldwide, alcohol consumption and abuse is associated with chronic pancreatitis in up to 70% of cases. In 1878, Friedreich proposed that ‘a general chronic interstitial pancreatitis may result from excessive alcoholism (drunkard’s pancreas).’ Since that observation, numerous studies have shown that a causal relationship exists between alcohol and chronic pancreatitis, but the prevalence of this etiology of the disease in Western countries ranges widely, from 38 to 94%. Other major causes worldwide include tropical (nutritional) and idiopathic disease, as well as hereditary causes.
There is a linear relationship between exposure to alcohol and the development of chronic pancreatitis. The risk of disease is present in patients with even a low or occasional exposure to alcohol (1 to 20 g/d), so there is no threshold level of alcohol exposure below which there is no risk of developing chronic pancreatitis. Furthermore, although the risk of disease is dose related, and highest in heavy (150 g/d) drinkers, 15% of confirmed alcohol abusers suffer from chronic pancreatitis. (See Schwartz 9th ed., p 1186, and Table 33-7.)
TABLE 33-7 Etiology of chronic pancreatitis
|
Alcohol, 70% Idiopathic (including tropical), 20% Other, 10% Hereditary Hyperparathyroidism Hypertriglyceridemia Autoimmune pancreatitis Obstruction Trauma Pancreas divisum |
30. Which of the following is the most commonly used initial treatment for pancreatic ascites?
A. Octreotide, bowel rest, TPN
B. Endoscopic stenting of the pancreatic duct
C. Roux-en-Y pancreaticojejunostomy
D. Distal pancreatectomy
Answer: A
ERCP is most helpful to delineate the location of the pancreatic duct leak in patients with pancreatic ascites and to elucidate the underlying pancreatic ductal anatomy. Pancreatic duct stenting may be considered at the time of ERCP, but if nonsurgical therapy is undertaken and then abandoned, repeat imaging of the pancreatic duct is appropriate to guide surgical treatment. Antisecretory therapy with the somatostatin analogue octreotide acetate, together with bowel rest and parenteral nutrition, is successful in more than half of patients. Reapposition of serosal surfaces to facilitate closure of the leak is considered a part of therapy, and this is accomplished by complete paracentesis. For pleural effusions, a period of chest tube drainage may facilitate closure of the internal fistula. Surgical therapy is reserved for those who fail to respond to medical treatment. If the leak originates from the central region of the pancreas, a Roux-en-Y pancreaticojejunostomy is performed to the site of duct leakage. If the leak is in the tail, a distal pancreatectomy may be considered, or an internal drainage procedure can be performed. The results of surgical treatment are usually favorable if the ductal anatomy has been carefully delineated preoperatively. (See Schwartz 9th ed., p 1204.)
31. The median survival following pancreaticoduodenectomy (Whipple procedure) for pancreatic cancer is approximately
A. 9 months
B. 2 years
C. 4 years
D. 8 years
Answer: B
Median survival after pancreaticoduodenectomy is about 22 months. Even long-term (5-year) survivors often eventually die due to pancreatic cancer recurrence. Although pancreaticoduodenectomy may be performed with the hope of the rare cure in mind, the operation more importantly provides better palliation than any other treatment, and is the only modality that offers any meaningful improvement in survival. If the procedure is performed without major complications, many months of palliation are usually achieved. It is the surgeon’s duty to make sure patients and their families have a realistic understanding of the true goals of pancreaticoduodenectomy in the setting of pancreatic cancer. (See Schwartz 9th ed., p 1230.)
32. Which of the following is the initial medication used to treat pain in patients with chronic pancreatitis?
A. Enteric-coated pancreatic enzyme preparations
B. Non–enteric-coated pancreatic enzyme preparations
C. Octreotide
D. Somatostatin
Answer: B
Conventional (non–enteric-coated) enzyme preparations are partially degraded by gastric acid but are available within the duodenal and jejunal regions to bind to CCK-releasing peptide, and downregulate the release of CCK. This theoretically reduces the enteric signal for pancreatic exocrine secretion, which reduces the pressure within a partially or completely obstructed pancreatic duct. Enteric-coated preparations result in little to no pain relief, presumably due to their reduced bioavailability in the proximal gut.
Somatostatin administration has been shown to inhibit pancreatic exocrine secretion and CCK release. The somatostatin analogue patients with chronic pancreatitis. In a double-blind, prospective, randomized 4-week trial, 65% of patients who received 200 μg of octreotide acetate subcutaneously three times daily reported pain relief, compared with 35% of placebo-treated subjects. Patients who had the best results were patients with chronic abdominal pain, suggestive of obstructive pancreatopathy. However, in another trial that used a 3-day duration of treatment, no significant pain relief was observed. None of the studies published thus far have examined the sustained-release formulation of octreotide, and it remains unclear what subgroups of patients, or what dose of octreotide, might be beneficial in the treatment of pain. (See Schwartz 9th ed., p 1206.)
33. In a patient with chronic pancreatitis, pancreatic stones, and a 6-mm pancreatic duct, which of the following treatments is most likely to result in symptomatic relief?
A. Endoscopic stone retrieval and stenting of the pancreatic duct
B. Transduodenal sphincteroplasty with retrieval of pancreatic stones
C. Caudal Roux-en-Y pancreaticojejunostomy (Duval procedure)
D. Longitudinal Roux-en-Y pancreaticojejunostomy (Puestow or Frey procedure)
Answer: D
Endoscopic removal of pancreatic duct stones is usually coupled to prolonged pancreatic duct stenting, which carries the risk of further inflammation. Despite the risk of perioperative complications, the surgical management of pancreatic duct stones and stenosis has been shown to be superior to endoscopic treatment in randomized clinical trials in which the long, side-to-side technique of pancreaticojejunostomy is used.
The effectiveness of decompression of the pancreatic duct is dependent on the extent to which ductal hypertension is the etiologic agent for the disease. Thus, the diameter of the pancreatic duct is a surrogate for the degree of ductal hypertension, and the Puestow procedure has been shown to be effective for pain relief when the maximum duct diameter is 6 mm.
Zollinger and associates described the caudal Roux-en-Y pancreaticojejunostomy for the treatment of chronic pancreatitis in 1954. The so-called Duval procedure was used for decades by some surgeons, but it almost invariably failed due to restenosis and segmental obstruction of the pancreas due to progressive scarring.
Successful pain relief after the Puestow-type decompression procedure has been reported in 75 to 85% of patients for the first few years after surgery, but pain recurs in >20% of patients after 5 years, even in patients who are abstinent from alcohol. (See Schwartz 9th ed., p 1210.)
34. Pancreas divisum occurs as a result of
A. Pancreatitis
B. Carcinoma of the pancreas
C. Trauma
D. Abnormal fusion of the pancreatic ducts
Answer: D
An understanding of embryology is required to appreciate the common variations in pancreatic duct anatomy. The pancreas is formed by the fusion of a ventral and dorsal bud. The duct from the smaller ventral bud, which arises from the hepatic diverticulum, connects directly to the common bile duct. The duct from the larger dorsal bud, which arises from the duodenum, drains directly into the duodenum. The duct of the ventral anlage becomes the duct of Wirsung, and the duct from the dorsal anlage becomes the duct of Santorini. With gut rotation, the ventral anlage rotates to the right and around the posterior side of the duodenum to fuse with the dorsal bud. The ventral anlage becomes the inferior portion of the pancreatic head and the uncinate process, while the dorsal anlage becomes the body and tail of the pancreas. The ducts from each anlage usually fuse together in the pancreatic head such that most of the pancreas drains through the duct of Wirsung, or main pancreatic duct, into the common channel formed from the bile duct and pancreatic duct.
In 10% of patients, the ducts of Wirsung and Santorini fail to fuse. This results in the majority of the pancreas draining through the duct of Santorini and the lesser papilla, while the inferior portion of the pancreatic head and uncinate process drains through the duct of Wirsung and major papilla. This normal anatomic variant, which occurs in one out of 10 patients, is referred to as pancreas divisum(Fig. 33-6). In a minority of these patients, the minor papilla can be inadequate to handle the flow of pancreatic juices from the majority of the gland. This relative outflow obstruction can result in pancreatitis and is sometimes treated by sphincteroplasty of the minor papilla. (See Schwartz 9th ed., p 1171.)
FIG. 33-6. Embryology of pancreas and duct variations. The duct of Wirsung from the ventral bud connects to the bile duct, while the duct of Santorini from the larger dorsal bud connects to the duodenum. With gut rotation, the two ducts fuse in most cases such that the majority of the pancreas drains through the duct of Wirsung to the major papilla. The duct of Santorini can persist as a blind accessory duct or drain through the lesser papilla. In a minority of patients, the ducts remain separate, and the majority of the pancreas drains through the duct of Santorini, a condition referred to aspancreas divisum.