GI Radiology > Pancreas > Neoplastic > Carcinoma

Pancreatic Carcinoma

Benign and malignant neoplastic lesions of the pancreas produce a variety of morphologic changes in the pancreas that can be detected by different imaging modalities. Pancreatic cancers account for 2% of all cancers, and comprise 5% of all cancer deaths. The survival rate for pancreatic cancers remains low at 4%; it is up from 3% in 1974-76. The list below shows the various types of pancreatic neoplasms.

Pancreatic Neoplasms

  • Ductal Adenocarcinoma
  • Intraductal papillary mucinous tumor
  • Nonductal neoplasms
    • Cystic neoplasms
      • Mucinous macrocystic neoplasm
      • Serous microcystic neoplasm
    • Endocrine tumors
      • Insulinoma
      • Gastrinoma
      • Glucagonoma
      • VIPoma
      • Somatostatinomas
    • Solid & papillary epithelial neoplasm
    • Metastasis

Initial symptoms of pancreatic adenocarcinoma are frequently non-specific. Abdominal pain, jaundice, and weight loss are common. Most (60-70%) of these tumors are in the head of the pancreas, and 70% of these patients have obstructive jaundice as a result of common bile duct obstruction. Patients with more advanced cancers experience weight loss secondary to anorexia and pancreatic insufficiency. Lab studies reveal elevated serum bilirubin, transaminases, alkaline phosphatase. Levels of pancreatic enzymes (amylase, lipase, and elastase I) are elevated in only 30% of patients due to main pancreatic duct obstruction. Tumor markers (CA19-9, DUPAN 2, Span 1, CEA) are reliable indicators of advanced pancreatic carcinomas, but are rarely useful in diagnosis of early stage tumors.

Tumors in the head of the pancreas are often detected earlier (at a smaller size), because they quickly invade vital structures to cause symptoms. Tumors of the body and tail are often larger at the time of presentation. Carcinoma of the ampulla has the best prognosis, because these lesions are detected at a smaller size/cause symptoms of presentation earlier. In the United States, only 1-2% of patients with pancreatic carcinoma live 5 years beyond the time of diagnosis, making early diagnosis critical.

Ultrasound (US):

On US, pancreatic adenocarcinomas appears as a hypoechoic mass, with poorly demarcated borders, that enlarges the pancreas and deforms its contour. Carcinomas as small as 5 mm can be visualized on US. US is also sensitive in demonstrating pancreatic and biliary duct dilatation secondary to tumor obstruction. In cases of small tumors, ductal dilatation may be the only sonographic evidence of disease. Extraglandular extension (into vascular structures) is also a common feature of advance tumors; color doppler is particularly useful in demonstrating involvement of the major vessels. Hepatic and lymph node metastases are easily visualized, although peritoneal metastases are more difficult to diagnose by US. Focal pancreatitis may be indistinguishable, unless calcifications are present (which are rare in adenocarcinomas).

Endoscopic US (EUS) can provide more sensitive imaging in the diagnosis and staging of adenocarcinoma. EUS is indicated in patients with small masses on US or CT, or patients with suspected adenocarcinoma, but negative US and CT. With EUS, the body and tail of the pancreas, the splenic vein, and left kidney are visualized from the stomach; the head of the pancreas, pancreatic duct system, portal vein, and common bile duct, are all visualized from the duodenum. Compared to other modalities (US, CT, ERCP, and angiography), EUS is reported to be the most sensitive for the visualization of pancreatic adenocarcinoma.

Computed Tomography (CT):

Intravenous contrast-enhanced helical CT is the radiologic modality of choice for diagnosing and staging pancreatic adenocarcinomas. Oral contrast is also used to delineate the borders of the small bowel. Tumors as small as 2 cm may be visualized with helical CT. The tumors appear as a hypoattenuating mass on contrast-enhanced CT (since they are hypovascular). The tumor margins are poorly defined, and calcification is rare. Secondary CT findings suggestive of adenocarcinoma include atrophy of the distal gland, and dilatation of the proximal pancreatic duct and bile duct. Differentiation of dilated duct between chronic pancreatitis and carcinoma may be difficult unless other findings of pancreatitis are present (calcifications, pseudocysts).

Advanced adenocarcinomas frequently invade peripancreatic vessels and adjacent organs (stomach, duodenum, colon, spleen, left kidney, adrenal gland). CT can demonstrate the encasement these vessels, and show the perivascular adventitial changes associated with tumor infiltration (thickening of caliber of the vessel). Liver metastases are also visualized as hypoattenuating masses, while lymph node metastases present as nodal enlargement.

Adenocarcinoma Findings on CT

-Focal hypoattenuating mass (red arrow)
-Atrophy of the gland distal to the mass
-Change in shape of pancreas, even in absence of mass
-Bile duct dilation (red arrow)
-Loss of sharp margins w/ surrounding structures
-Fat plane obliteration/invasion

Endoscopic Retrograde Cholangiopancreatography (ERCP):

ERCP is highly accurate in the diagnosis of pancreatic adenocarcinoma; ERCP can demonstrate very small lesions that arise from the duct epithelium. Although some of the changes in ERCP are nonspecific for carcinoma, they direct further investigation. Abnormalities of the pancreatic ductal system include obstruction, duct dilation, and extravasation of contrast into the tumor. The tables below highlights some common ductal findings on ERCP.

Ductal Changes in Adenocarcinoma

Stenosis and prestenotic dilatation
Double duct sign: stenosis of both the main pancreatic duct and the common bile duct, with prestenotic dilatation. (Not specific for tumor; may be seen in focal pancreatitis).
Broken contour: duct stops abruptly
Focal side branch distortion, obstruction, amputation, filling of necrotic zone
Pott G, Schrameyer B., ERCP Atlas. Phila.: B. C. Decker, Inc., 1989, p 82.

ERCP Findings in Adenocarcinoma

Left: proximal stenosis with prestenotic dilation

Above: Double duct sign: stenosis of CBD and main pancreatic duct Above: Common bile duct obstruction presenting with painless jaundice

Magnetic Resonance Cholangiopancreatography (MRCP):

MRCP may also be of assistance in the diagnoses of pancreatic adenocarcinoma. MRCP can depict strictures and dilation of the main pancreatic duct. In some institutions, MRCP has replaced diagnostic ERCP in the diagnosis of adenocarcinoma.

Magnetic Resonance Imaging (MRI):

Ductal adenocarcinoma may be evalauated with MRI using the same general criteria used for other imaging modalities. Recent studies have shown MRI techniques to be equal or superior to those of CT in depicting tumor and peripancreatic extension. T1 weighted MRI images are required for the diagnosis of pancreatic adenocarcinoma; the tumors appear as lesions of low signal intensity. (On T2 weighted images, tumors and normal parenchyma show little or no variation in intensity.) Differentiation between pancreatitis and pancreatic carcinoma cannot be made using signal intensity findings on T1- and T2-weighted images.

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