Diagnostic Ultrasound - Abdomen and Pelvis

Pancreatic Pseudocyst
Diagnoses: Pancreas
• No pancreatic ductal dilatation
PATHOLOGY
General Features
• Etiology
○ Pseudocysts develop in 10-20% of patients with APFC
○ Pathogenesis
– Release of enzymes and pancreatic juice
□ Rupture of pancreatic duct
□ Exudation of fluid from surface of pancreas due to
activation of enzymes within gland
– Unabsorbed APFC organize and develop fibrous
capsule within 4-6 weeks
– Develop due to post-traumatic/inflammatory
autodigestion of pancreas
– Walls arise from reaction of surrounding tissue to
inflammatory exudate
• Associated abnormalities
○ Acute or chronic pancreatitis
Gross Pathologic & Surgical Features
• Collection of fluid, tissue, debris, pancreatic enzymes, and
blood covered by thin rim of fibrous capsule
Microscopic Features
• Inflammatory cells, necrosis, hemorrhage
• Absence of epithelial lining
• Wall consists of granulation tissue and fibrosis
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Clinical significance is related to size and complications
– Abdominal pain, typically radiating to back
– Palpable, tender mass in middle or left upper
abdomen
• Other signs/symptoms
○ May be asymptomatic throughout clinical course
• Clinical profile
○ Patient with history of chronic alcoholism, abdominal
pain, and palpable tender mass
• Lab data
○ Cyst aspiration: Elevated amylase and lipase
○ Acute pancreatitis
– Increased serum amylase and lipase
○ Chronic pancreatitis
– Serum markers, exocrine function tests not helpful
nor readily available
Demographics
• Age
○ More common in young and middle-aged group
• Gender
○ M > F
• Epidemiology
○ Rarely form during initial attack of pancreatitis (1-3% of
patients)
○ Develop after several episodes of alcoholic pancreatitis
in 12% of patients
○ Present in up to 40% of patients with chronic
pancreatitis
Natural History & Prognosis
• May persist, resolve, or continue to grow
• Spontaneous resolution can occur in 25-40%
• Complications: More common in pseudocysts > 4-5 cm in
size
○ Compression of adjacent bowel or bile duct
– Obstruction, severe pain, jaundice
○ Spontaneous rupture into peritoneal cavity
– Ascites, peritonitis
○ Fistula to bowel
○ Secondary infection
○ Erosion into adjacent vessel
– Hemorrhage or pseudoaneurysm formation
• Rupture and hemorrhage are prime causes of death from
pseudocyst
Treatment
• Conservative therapy
○ If asymptomatic or decrease in size on serial scans
• Drainage
○ If symptomatic or continued increase in size
– Size alone not indication for drainage
○ Drainage routes
– Percutaneous: Retroperitoneal, transperitoneal,
transhepatic
– Endoscopic: EUS-guided cystogastrostomy
– Surgical: Internal (usually into stomach) or external
drainage
○ Requires long-term catheter if pseudocyst still
communicates with pancreatic duct
○ Curative in up to 90% of cases
DIAGNOSTIC CHECKLIST
Consider
• Rule out other cystic lesions of pancreas, particularly
mucinous neoplasms
Image Interpretation Pearls
• Correlate with ancillary imaging findings and clinical
evidence of prior pancreatitis to confirm diagnosis
• Cyst aspiration may be required for definitive diagnosis
SELECTED REFERENCES
1. Banks PA et al: Classification of acute pancreatitis--2012: revision of the
Atlanta classification and definitions by international consensus. Gut.
62(1):102-11, 2013
2. Kucera JN et al: Cystic lesions of the pancreas: radiologic-endosonographic
correlation. Radiographics. 32(7):E283-301, 2012
3. Thoeni RF: The revised atlanta classification of acute pancreatitis: its
importance for the radiologist and its effect on treatment. Radiology.
262(3):751-64, 2012
4. Khan A et al: Cystic lesions of the pancreas. AJR Am J Roentgenol.
196(6):W668-77, 2011
5. Kim YH et al: Imaging diagnosis of cystic pancreatic lesions: pseudocyst
versus nonpseudocyst. Radiographics. 25(3):671-85, 2005
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