Basics
- A pancreatic pseudocyst is a peripancreatic (or intrapancreatic) fluid collection associated with a history of pancreatitis, that is surrounded by a well-defined inflammatory wall, and that has no solid component.
- The term "pseudocyst " is often incorrectly used to define various types of fluid collections associated with pancreatitis. As a result, medical literature on pseudocysts is not consistent in its descriptions or its findings.
- An important distinction between "fluid collections " associated with pancreatitis is that some consist of fluid alone, whereas others arise from necrosis of pancreatic parenchyma and/or peripancreatic tissues. The latter type of fluid collection involves a solid component (with variable amounts of fluid), which distinguishes them from pseudocysts.
- Types of fluid collections:
- Acute peripancreatic fluid collection (APFC)
- A fluid collection that develops in the early phase of interstitial edematous acute (typically mild) pancreatitis
- Lack a well-defined wall on CT scan
- NOT associated with necrotizing pancreatitis
- Remain sterile, and usually resolve without intervention
- If APFC persists beyond 4 weeks, likely to develop into a pancreatic pseudocyst; although this is considered a rare outcome.
- Pancreatic pseudocyst
- Refers specifically to a peripancreatic (or less commonly, an intrapancreatic) fluid collection
- Surrounded by a well-defined inflammatory wall and containing NO solid material
- Pancreatic pseudocysts develop more than 4 weeks after the onset of interstitial pancreatitis.
- Acute necrotic collection (ANC)
- A collection of BOTH variable amounts of fluid and solid (necrotic) material related to pancreatic and/or peripancreatic necrosis
- Occur within the first 4 weeks of disease, and can resemble an APFC in the first few days of acute pancreatitis
- As necrotizing pancreatitis develops and necrosis evolves, solid component become evident.
- May be multiple and may involve the pancreatic parenchyma alone, the peripancreatic tissue alone, or most commonly both
- May be infected or sterile
- Generally associated with more severe sequelae of AP
- Walled-off necrosis (WON)
- Collection of varying amounts of liquid and solid material surrounded by a mature, enhancing wall of reactive tissue
- Represents a mature, encapsulated ANC
- Develops no earlier than 4 weeks after episode of necrotizing pancreatitis
- May be multiple and present at sites distant from the pancreas
- May be sterile or infected
Pathophysiology
- Pseudocysts occur when there is disruption in the pancreatic ductular system, or its intrapancreatic branches, without any evidence of pancreatic or peripancreatic necrosis.
- This results in the extravasation of pancreatic enzymes evoking an inflammatory response.
- The inflammatory reaction leads to a fluid collection that is rich in pancreatic enzymes (APFC).
- If the duration of the fluid collection is >4 weeks, becomes localized (intrapancreatic or extrapancreatic), and develops a fibrin capsule, it becomes a pseudocyst.
- A pseudocyst does not have a true epithelial lining.
- If there is communication between the pseudocyst and the pancreatic duct, the enzyme level in the fluid remain elevated; if there is no communication, the enzyme level falls with time.
Diagnosis
History
Acute or chronic pancreatitis
- Suspect pancreatic pseudocyst in patients recovering from acute pancreatitis, or in the patient with chronic pancreatitis, who has recurrent/persistent abdominal pain, a palpable abdominal mass, or persistently elevated serum pancreatic enzymes.
Physical Exam
- Abdominal tenderness
- Abdominal mass
- Nausea and vomiting
- Weight loss
- Jaundice
- Abdominal distention
- In many situations, no clinical signs are seen.
- Clinical signs may be secondary to complications:
- Jaundice in hepatobiliary obstruction
- Lower limb edema in compression of inferior vena cava
- Ascites in peritonitis
- Pleural effusion
Diagnostic Tests & Interpretation
Lab
Serum pancreatic enzyme levels:
- Persistently elevated enzymes in blood can be a clue, but is not an absolute indicator.
- Elevated enzymes in fluid drained from a peripancreatic or intrapancreatic fluid collection with no solid component is consistent with a pancreatic pseudocyst.
Imaging
- CT scan
- Reveals pseudopancreatic cyst; can also be used to gauge size of pseudocyst and its relationship to adjacent organs
- Ultrasonography
- Visualizes pancreatic pseudocysts
- Can be used to follow cyst size over time
- Endoscopic ultrasonography (EUS)
- Common modality in adult patients and increasingly used in pediatrics
- Can be used to diagnose presence and size of pseudocyst; can also be used to guide peroral fluid aspiration and drainage
- Endoscopic retrograde cholangiopancreatography (ERCP)
- Used in some cases to delineate the pancreatic ductular system before drainage to distinguish ductal stenosis, disruption, stones, and other obstructions
Differential Diagnosis
- Congenital/genetic
- Congenital cysts
- Polycystic disease
- Von Hippel-Lindau disease
- Cystic fibrosis
- Infections
- Pancreatic abscess
- Echinococcal (hydatid) cyst
- Taenia solium cyst
- Tumor
- Serous cystadenoma
- Mucinous cystadenoma
- Cystic islet cell tumors
- Teratoma
- Pancreatoblastoma
- Cystadenocarcinoma
- Franz tumor
- Angiomatous cystic neoplasms
- Lymphangiomas
- Hemangioendothelioma
- Miscellaneous:
- Splenic cyst
- Adrenal cyst
- Enterogenous cyst
- Duplication cysts
- Endometriosis
Treatment
General Measures
- Medical management:
- Most cases resolve with supportive care.
- If eating precipitates pain, short-term nasojejunal feedings or parenteral nutrition may be warranted.
- Follow up with ultrasound or CT scan to make sure there are no complications.
- >60% have complete resolution by the end of 1 year.
- Usually, no medications are used for managing pseudocysts.
- Somatostatin analogue (octreotide) has been reported to be used to decrease fluid collection along with drainage.
- Antibiotics are used in situations of infected pseudocyst.
- Drainage
- Most often used in the setting of WON
- Indications: infection, rupture with cardiopulmonary compromise, biliary and gastric outlet obstruction, persistent symptoms, rapid enlargement, failure of large pseudocysts (>6 cm) to shrink after 6 weeks
- Modalities:
- Percutaneous drainage (aspiration or catheter drainage) is done in cases in which the pseudocyst has a less mature wall.
- Percutaneous aspiration has a high recurrence rate of 63% and failure rate of 54%.
- Continuous drainage has a recurrence rate of 8% and a failure rate of 19%.
- Endoscopic procedures are becoming the 1st-line drainage modality, as they are less invasive than surgery.
- Endoscopic procedures include transmural cystoenterostomies and transpapillary route procedures such as stent placement for pseudocysts that communicate with the main pancreatic duct.
- Endoscopic procedures in experienced hands report success rates of 82 " 89%, complication rates of 10 " 20%, and recurrence rates of 6 " 18%.
Surgery/Other Procedures
- Reserved for failed endoscopic procedures, difficult to access areas of WON and multiple WONs
- Includes internal drainage (cystogastrostomy, cystoduodenostomy, and Roux-en-Y cystojejunostomy), resection, and external drainage
- Success rate is 85 " 90%.
- Recurrence rate is 0 " 17%.
- Mortality rate is between 3 and 5%.
Ongoing Care
Prognosis
Majority of pseudocysts resolve without intervention.
Complications
- Perforation/rupture
- Cardiopulmonary compromise secondary to pleural effusion and ascites
- Peritonitis and ascites, which can be fatal
- Hemorrhage
- Erosions of vessels lining the cyst cause intracystic bleeding and rapid increase in the cyst size.
- Bleeding may occur directly into stomach, duodenum (clinically manifesting as GI bleeding), or peritoneal cavity.
- Obstruction
- Biliary obstruction: jaundice
- Portal obstruction: portal hypertension
- Gastric outlet obstruction
- Inferior vena cava obstruction: peripheral edema
- Urinary obstruction
- Colonic obstruction
- Infection of pseudocysts is rare in children compared to adults:
- Associated with high mortality rate for children and adults
- Management usually requires surgical drainage.
Additional Reading
- Law NM, Freeman ML. Emergency complications of acute and chronic pancreatitis. Gastroenterol Clin. 2002;32(4):1169 " 1194. [View Abstract]
- Reber HA. Surgery for acute and chronic pancreatitis. Gastrointest Endosc. 2002;56(6)(Suppl):S246 " S248. [View Abstract]
- Sarr MG, Banks PA, Bollen TL, et al. The new revised classification of acute pancreatitis 2012. Surg Clin North Am, 2013;93(3):549 " 562. [View Abstract]
- Vidyarthi G, Steinberg SE. Endoscopic management of pancreatic pseudocysts. Surg Clin North Am. 2001;81(2):405 " 410. [View Abstract]
- Weckman L, Kylanpaa ML, Poulakkainen P, et al. Endoscopic treatment of pancreatic pseudocysts. Surg Endosc. 2006;20(4):603 " 607. [View Abstract]
Codes
ICD09
- 577.2 Cyst and pseudocyst of pancreas
ICD10
- K86.3 Pseudocyst of pancreas
SNOMED
- 111374002 pseudocyst of pancreas (disorder)
- 405563007 Infected pancreatic pseudocyst (disorder)