Diagnostic Ultrasound - Abdomen and Pelvis

Intraductal Papillary Mucinous Neoplasm (IPMN)
Diagnoses: Pancreas
TERMINOLOGY
• Cystic neoplasm of pancreas arising from mucin-producing
epithelium of main pancreatic duct (MPD) &/or side branch
pancreatic ducts (SBD) with variable malignant potential
IMAGING
• Main pancreatic duct type: > 5 mm; no obstructive cause
• Side branch duct type: Multicystic, grape-like cluster of cysts
contiguous with the MPD
• US: Not modality of choice: Difficult to evaluate entire
pancreas due to bowel gas and limited characterization
○ Nonspecific anechoic or hypoechoic mass ± PD dilatation
• Endoscopic ultrasound (EUS): Provides best morphologic
evaluation and opportunity for cyst aspiration &/or biopsy
• CT or MR: Important in identifying features associated with
increased risk of malignancy
• MRCP: Best noninvasive imaging modality for identification
of ductal communication
• Follow-up surveillance imaging with CEMR/MRCP
KEY FACTS
TOP DIFFERENTIAL DIAGNOSES
• Mucinous cystic pancreatic neoplasm
• Pancreatic serous cystadenoma
• Chronic pancreatitis
• Pancreatic pseudocyst
• Pancreatic ductal adenocarcinoma
CLINICAL ISSUES
• If high-risk stigmata present based on Tanaka criteria →
surgical resection
• If worrisome features present → EUS for biopsy/aspiration
• If no worrisome features present → follow-up interval
determined by cyst size
DIAGNOSTIC CHECKLIST
• Look for communication between cystic lesion and
pancreatic duct, which may be dilated
(Left) Graphic demonstrates
irregular, dilated main and
branch pancreatic ducts within
the head and uncinate process
of the pancreas, typical of
intraductal papillary mucinous
neoplasm (IPMN). (Right)
Transverse transabdominal
ultrasound shows marked
dilatation of the pancreatic
duct st that measures > 10
mm in the body of the
pancreas. Note the associated
ill-defined hypoechoic mass
posteriorly ſt.
(Left) Color Doppler
transabdominal ultrasound
demonstrates an anechoic
cystic lesion ſt
communicating with a dilated
main pancreatic duct st.
(Right) Axial T2WI in the same
patient better characterizes
the presence of multiple cystic
lesions ſt some of which show
communication with the
mildly dilated main pancreatic
duct st.
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