Diagnostic ultrasound ( PDFDrive )

CHAPTER 7 The Pancreas 229
he most important issue in diagnosing pseudocysts on images
is avoiding confusion with cystic neoplasm, a mistake that can
lead to adverse clinical outcomes. 75 Unfortunately, this distinction
may be diicult. he major criterion for diagnosing a pseudocyst
is a clinical history or imaging evidence of acute or chronic
pancreatitis. Failing this, diferentiating a pseudocyst from cystic
pancreatic lesions becomes problematic. he sonographic indings
in pseudocysts are variable. Pseudocysts can range in appearance
from almost purely cystic to collections with considerable
mural irregularity, septations, and internal echogenicity because
of debris (Fig. 7.41) from necrosis, hemorrhage (see Fig. 7.40),
or infection. Successful diferentiation of cystic neoplasm from
pseudocyst thus depends on a high degree of suspicion for possible
cystic neoplasm and understanding indings strongly suggestive
of “the usual suspects”: serous cystic neoplasm (microcystic
adenoma), mucinous cystic neoplasm, solid-pseudopapillary
tumor, and intraductal papillary mucinous neoplasm. 76
Characterization of cystic neoplasms by CT or MRI is unreliable,
even when the reviewers’ diagnostic certainty was 90%
or more. 77
Conservative management of pseudocysts is appropriate unless
complications occur. As noted, many pseudocysts resolve
spontaneously. Persistent uncomplicated pseudocysts require no
intervention and can be safely observed. 78,79 Indications for
drainage of a pseudocyst include abdominal pain, usually related
to growth of (or hemorrhage into) the pseudocyst, biliary obstruction
(Fig. 7.41), and gastrointestinal (usually duodenal) obstruction.
80 Internal or external istula formation can result in pancreatic
ascites or pleural efusion. 81 Inlammation from pancreatitis can
digest and dissect through tissue plane boundaries. For example,
pseudocysts and inlammatory masses can present in the neck 81,82
or the groin 83 (Fig. 7.42).
PC
L
RK
FIG. 7.40 Pancreatic Fracture and Associated Pseudocyst. Transverse
sonogram shows the fracture/laceration (arrow) of the pancreatic
body. A pseudocyst (PC) has developed ventral to the pancreas. Trauma
is an uncommon cause of pancreatic pseudocysts. (Courtesy of Stephanie
Wilson, MD.)
FIG. 7.42 Inlammation From Pancreatitis Causing Groin
Mass. Longitudinal extended ield of view sonogram from right upper
quadrant to right groin. An inlammatory mass (arrows) is caudal to the
inguinal ligament. Extensive spread of acute inlammation is common
in acute pancreatitis. L, Liver; RK, right kidney.
CBD
PS cyst
FIG. 7.41 Pseudocysts Causing Biliary Obstruction. Longitudinal oblique sonograms in two different patients demonstrate common bile duct
(CBD) dilation from obstruction. Biliary obstruction is an indication for pseudocyst (PS cyst) drainage.