Diagnostic ultrasound ( PDFDrive )

236 PART II Abdominal and Pelvic Sonography
TRANS
DIL ducts
FIG. 7.61 Many Small, Dilated Ducts. Transverse sonogram shows
multiple dilated branch ducts in the pancreatic head, more typical of
chronic pancreatitis and rarely found in pancreatic cancer.
FIG. 7.60 Mass With Color Comet-Tail Artifact From Calciication.
Transverse sonogram reveals a mass (arrow). Calciication, revealed
by a prominent color comet-tail artifact, indicates a likely diagnosis of
chronic pancreatitis.
that of patients with the usual chronic pancreatitis. In chronic
pancreatitis calciications are multiple and ductal. In carcinoma
there are generally only one or a few coarse calciications, usually
unrelated to dilated ducts. Hyperechoic masses, even without
discrete calciications, are usually (but not always) related to
chronic pancreatitis. An uncalciied isoechoic or hypoechoic
mass occurring in a patient without clinical or imaging evidence
of chronic pancreatitis is nonspeciic. In this case, other imaging
or biopsy is indicated to diferentiate carcinoma from chronic
pancreatitis. As noted, the double-duct sign is nonspeciic,
occurring in both pancreatitis and pancreatic carcinoma. Finding
multiple dilated branch ducts in the pancreatic head is more
typical of chronic pancreatitis and is rarely found in pancreatic
cancer (Fig. 7.61). Pseudocysts are common in chronic pancreatitis
(20%-40%) 74 and rare in carcinoma, 112 but they occur in both
conditions. So-called obstructive pseudocysts that occur with
carcinoma usually are peripheral to body or tail lesions.
Pancreatitis-associated pseudocysts occur anywhere in the gland,
usually arising in areas of necrosis.
Autoimmune pancreatitis is a masslike imitator of pancreatic
carcinoma 113 (Figs. 7.62 and 7.63). Autoimmune pancreatitis
accounts for many cases previously classiied as “idiopathic
pancreatitis,” comprising perhaps 4% to 6% of all patients
diagnosed with chronic pancreatitis. he autoimmune pancreatitis
terminology is confusing; synonyms include chronic sclerosing
pancreatitis, lymphoplasmacytic sclerosing pancreatitis, and
tumefactive chronic pancreatitis. 114 About 2% of pancreatic
masses resected for suspected malignancy are found instead to
be autoimmune pancreatitis. 115 Although benign masses from
the usual causes of chronic pancreatitis are more common,
autoimmune pancreatitis masses are much more likely to be
confused for carcinoma. 116 In one series, 13 of 19 (68%) masses
caused by the usual types of chronic pancreatitis were resected
for a clinical suspicion of malignancy, whereas all 11 (100%) of
autoimmune pancreatitis–related masses were thought to be
malignant preoperatively. 109
Anecdotal experience suggests that when a deinite pancreatic
mass is seen sonographically but not imaged on CT, chronic
pancreatitis is the likely cause of the mass. Another slightly
confounding fact is that patients with chronic pancreatitis have
an increased lifetime risk of developing pancreatic carcinoma
(4%) 117 compared with the general population (1%-2%). 118
PANCREATIC NEOPLASMS
Periampullary Neoplasm
Periampullary neoplasms are diicult to diferentiate from one
another and are generally managed identically—by pancreaticoduodenectomy
(Whipple resection). Jaundice is the most
common presenting feature of these tumors (85%). 119 Tumors
in this group include pancreatic ductal adenocarcinoma (about
two-thirds of periampullary neoplasms), ampullary carcinoma
(15%-25%), duodenal carcinoma (10%), and distal cholangiocarcinoma
(10%). 119 Survival rates are best for patients with
duodenal and ampullary carcinoma, but only in comparison to
the poor survival rates for those with cholangiocarcinoma and
especially pancreatic cancer.
Image evaluation of these tumors is basically the same as that
described later for pancreatic ductal adenocarcinoma. he
approach varies depending on the clinical presentation and local
expertise. Most agree, however, with Ross and Bismar, 119 that
“the relative availability, economy, and usefulness of the results
make transabdominal ultrasound a common initial imaging study
for patients with suspected obstructive jaundice.”
Pancreatic Carcinoma
Pancreatic ductal adenocarcinoma is the most common primary
pancreatic neoplasm, accounting for 85% to 95% of all pancreatic