Diagnostic Ultrasound - Abdomen and Pelvis

Pancreatic Duct Dilatation
Differential Diagnoses: Pancreas
DIFFERENTIAL DIAGNOSIS
Common
• Chronic Pancreatitis
• Pancreatic Ductal Carcinoma
• Periampullary Tumor
Less Common
• Obstructing Distal Common Bile Duct Stone
• Intraductal Papillary Mucinous Neoplasm (IPMN)
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
• Pancreatic ductal dilatation: > 3 mm possibly with tortuous
configuration
○ May see abrupt tapering at site of obstruction
○ Should prompt thorough search for obstructing lesion at
the papilla or in pancreatic head
– US may not provide adequate visualization due to
overlying bowel gas or body habitus
– CT, MR &/or endoscopic US should be considered
• Isolated pancreatic duct dilatation
○ Most commonly due to chronic pancreatitis
○ High possibility of pancreatic cancer if no evidence of
chronic pancreatitis
○ Mild, idiopathic dilatation without tortuosity, frequently
seen in elderly patients
• When associated with biliary duct dilatation, termed
"double duct" sign
○ Etiology more likely malignant disease; most commonly
pancreatic ductal adenocarcinoma
○ Obstructing common bile duct stone or benign stenosis
are also possibilities if patient does not have jaundice or
mass
Helpful Clues for Common Diagnoses
• Chronic Pancreatitis
○ Clinical history of longstanding recurrent attacks of
epigastric pain; typically radiates to back
○ Atrophic pancreas with irregular outline and
heterogeneous, hypo-/hyperechoic echo pattern
○ Pancreatic calcification: Intraductal and parenchymal
○ May see dilated side branches when severe
○ MR may show duct dilatation with strictures → more
suggestive of chronic pancreatitis than IPMN
• Pancreatic Ductal Carcinoma
○ Causes pancreatic duct obstruction as tumor arises from
ductal epithelium of exocrine pancreas
○ Irregular, ill-defined, solid, hypoechoic mass
○ Pancreatic duct dilatation upstream from tumor
○ Bile duct dilatation with tumor in pancreatic head
○ Lack of pancreatic calcification or ductal calculus
○ May see liver and regional lymph node metastases
Helpful Clues for Less Common Diagnoses
• Obstructing Distal Common Bile Duct Stone
○ Obstructive jaundice and epigastric pain
○ Presence of bile duct dilatation
• Intraductal Papillary Mucinous Neoplasm (IPMN)
○ Main duct type shows marked diffuse pancreatic ductal
dilatation ± pancreatic atrophy
– Calcification not typically seen and is more suggestive
of chronic pancreatitis
– Mural/intraluminal nodularity or associated soft tissue
mass is suggestive of malignancy
○ Side branch duct type may show mild ductal dilatation
communicating with cystic pancreatic lesion
– Grape-like cluster of cysts with IPMN vs. unilocular cyst
with chronic pancreatitis
SELECTED REFERENCES
1. Cohen J et al: Double-duct sign in the era of endoscopic ultrasound: the
prevalence of occult pancreaticobiliary malignancy. Dig Dis Sci. 59(9):2280-5,
2014
2. Kim JH et al: Intraductal papillary mucinous neoplasm of the pancreas:
differentiate from chronic pancreatits by MR imaging. Eur J Radiol.
81(4):671-6, 2012
3. Tanaka S et al: Slight dilatation of the main pancreatic duct and presence of
pancreatic cysts as predictive signs of pancreatic cancer: a prospective study.
Radiology. 254(3):965-72, 2010
(Left) Transverse
transabdominal ultrasound
shows pancreatic ductal
dilatation ſt in the atrophic
body of the pancreas with
parenchymal and
intraluminal calcifications st.
(Right) Axial transabdominal
color Doppler ultrasound
shows the double duct sign of
biliary (calipers) and
pancreatic duct ſt dilatation
due to an ill-defined mass in
the head of the pancreas st
better seen on a more inferior
plane.
Chronic Pancreatitis
Pancreatic Ductal Carcinoma
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