pancreatic cyst

Etiology

• idiopathic
• von Hippel-Lindau disease
• may be associated with pancreatitis or simply diagnosed after an episode of pancreatitis*

* only pancreatic pseudocyst mentioned in ref after episode of pancreatitis

Epidemiology

• prevalence may be up to 20% in general population
• 1% at age 40, 9% at age 80 years
• mucin-producing pancreatic cysts occur almost exclusively in women (>98%)

Pathology

• true cyst with epithelial lining, containing
  • pool of pancreatic fluid
  • semisolid matter made up of debris or necrotic tissue
• mucinous cystic neoplasms*
  • found in the pancreatic body or tail in 90% of cases
• intraductal papillary mucinous neoplasms
• may involve the main pancreatic duct, its branches or both
• malignant potential is low
• less hazzardous than pancreatic pseudocyts

* non-mucin producing cysts have no malignant potential

Clinical manifestations

• frequently asymptomatic
• abdominal pain with radiation to the back
• nausea/vomiting
• abdominal bloating

Laboratory

• CA 19-9 may be a useful serum tumor marker
• cystic fluid analysis
  • CEA in body fluid is high in mucinous adenomas
  • amylase in body fluid is high if pseudocyst & low to variable in adenomas

Diagnostic procedures

• abdominal ultrasound
• endoscopic ultrasound with fine neeedle aspiration (EU-FNA) of cyst to rule out mucinous adenocarcinoma
  • indicated for cysts >= 2 high-risk features
    • size >= 3 cm
    • dilated main pancreatic duct
    • associated solid component
  • not recommended in patients with imaging characteristic of resectable pancreatic cancer; surgical resection recommended prior to histopathology for diagnosis
  • not indicated for pancreatic pseudocyst
• endoscopic cytology & biopsy
• percutaneous fine-needle biopsy/aspiration
  • positive mucin stain &/or elevated CEA in aspirated fluid suggests mucinous adenocarcinoma

Radiology

• computed tomography of the abdomen
• pancreatic cysts detected incidentally on abdominal CT
  • cysts with characteristics of serous cystadenomas (multicystic, lobulated structures resembling a bunch of grapes, with or without calcification) have no malignant potential & need no surveillance (see below
  • cysts with risk features should be evaluated with magnetic resonance cholangiopancreatography (MRCP) before determining risk profile for further surveillance
  • ref suggests you cannot determine risk features from non-pancreatic abdominal CT, thus apparently all pancreatic incidentomas need MRCP
• surveillance with MRI for cysts without high-risk features* at 1 year, then every 2 years for 5 years if cyst is not changing

* see above (endoscopic ultrasound) for high-risk features

Complications

• infection leading to pancreatic abscess
• biliary obstruction
• portal hypertension
• less likely to rupture than pancreatic pseudocyts
• malignant transformation (pancreatic cancer) 0.03%
  • most pancreatic cysts never become malignant*
  • increase in size (27%)
  • delayed growth after 1, 2, or 3 years of initial stability 11%, 6%, & 1.5%, respectively
  • within 4.8 years, 1 of 259 patients died from a pancreatic cancer that developed at a site distant from cyst
  • a second patient's cyst enlarged into an intraductal papillary mucinous neoplasm with high-grade dysplasia*

* exception is intraductal papillary mucinous neoplasms involving the main pancreatic duct

Differential diagnosis

• pancreatic cancer
  • mucinous adenocarcinoma
  • cystadenocarcinoma (generally painful)
• benign pancreatic cystadenoma (generally painless)
• wall-off pancreatic necrosis
• pancreatic pseudocyst
  • differentiating pancreatic cysts from pancreatic pseudocysts can be difficult because there is no definitive test with high sensitivity & specificity
  • only pancreatic pseudocyst mentioned in ref after episode of pancreatitis

Management

• observation if asymptomatic
• cyst drainage
  • endoscopic drainage
  • percutaneous catheter drainage
  • surgical drainage
    • laparoscopy vs open surgery
• surgical resection for cysts with both a solid component & a dilated pancreatic duct or if EU-FNA results suggests malignancy
  • surveillance after surgical resection in patient with invasive cancer or high-grade dysplasia in resected cyst

More general terms

• cyst
• pancreatic disease

Additional terms

• pancreatic necrosis
• pancreatic pseudocyst