Diagnostic Ultrasound - Abdomen and Pelvis

Pancreatic Pseudocyst
Diagnoses: Pancreas
TERMINOLOGY
• Collection of pancreatic fluid and inflammatory exudate
encapsulated by nonepithelial fibrous tissue developing > 4
weeks after acute pancreatic fluid collection (APFC)
IMAGING
• Well-defined unilocular peripancreatic cystic mass in setting
of prior pancreatitis
○ 2/3 are peripancreatic: Body and tail (85%)
• US demonstrates well-circumscribed, smooth-walled,
unilocular anechoic mass with posterior acoustic
enhancement
○ Complex pseudocysts may have fluid-debris level,
internal echoes, or septations (due to
hemorrhage/infection)
• CT best to evaluate extent of pseudocyst and complications
○ Gas within pseudocyst: Infection vs. decompression into
stomach or bowel
KEY FACTS
• MRCP helpful to visualize communication with pancreatic
duct
TOP DIFFERENTIAL DIAGNOSES
• Mucinous cystic neoplasm
• Serous cystadenoma
• Intraductal papillary mucinous neoplasm (IPMN) of
pancreas
• Cystic islet cell tumor
• True epithelial cysts
CLINICAL ISSUES
• Clinical significance is related to size and complications
• Percutaneous drainage required when symptomatic or
enlarging
DIAGNOSTIC CHECKLIST
• Rule out other cystic lesions of pancreas, particularly
mucinous neoplasms
• Cyst aspiration may be required for definitive diagnosis
(Left) Graphic shows a wellcircumscribed
cystic lesion ſt
in the pancreatic body
consistent with a pancreatic
pseudocyst. The adjacent
pancreatic duct is not
compressed or displaced.
(Right) Transverse ultrasound
through the left upper
quadrant shows a wellcircumscribed,
unilocular
pseudocyst in the pancreatic
tail ſt. Posterior acoustic
enhancement is noted. The
spleen st provides an acoustic
window.
(Left) Transverse ultrasound
via left posterolateral
approach shows a wellcircumscribed,
unilocular
simple cyst ſt at the
pancreatic tail, consistent with
pseudocyst. (Right) Transverse
ultrasound of the midbody of
the pancreas shows a lobular
pseudocyst ſt in the
pancreatic head, separated
from the adjacent dilated
pancreatic duct by a thin
septation .
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