Pancreatic pseudocyst is a pancreatic fluid collection that develops after acute or chronic pancreatitis, lacking an epithelial lining and surrounded by inflammatory granulation tissue and fibrosis. Unlike true cysts, it has no epithelial covering — hence the name 'pseudo' (false) cyst. According to the revised Atlanta classification (2012), these are well-defined walled-off collections with homogeneous fluid content that mature ≥4 weeks after acute pancreatitis. Duct communication is common and develops as a result of pancreatic duct injury.
Age Range
30-70
Peak Age
50
Gender
Male predominant
Prevalence
Common
Pseudocyst forms when pancreatic secretions and inflammatory fluid leak into the peritoneal cavity or peripancreatic space as a result of pancreatic duct injury or parenchymal necrosis. In acute pancreatitis, duct disruption causes fluid leakage; this fluid initially accumulates as a free collection (acute peripancreatic fluid collection), then within 4 weeks the inflammatory response in surrounding tissues forms a fibrous capsule — this is the 'maturation' process. The pseudocyst wall consists of inflammatory granulation tissue, fibrosis, and adjacent organ walls (stomach, colon, peritoneum) rather than epithelium. The fluid content is rich in pancreatic enzymes (amylase, lipase), and this enzyme profile is used diagnostically on aspiration. In chronic pancreatitis, recurrent inflammation and fibrosis lead to duct obstruction, forming retention cysts and pseudocysts. On imaging, pseudocyst appears as a homogeneous fluid-density/signal collection surrounded by a thin smooth enhancing wall without solid components.
Visualization of a thin (<2-4 mm), smooth, homogeneously enhancing fibrous wall around the pseudocyst in the portal venous phase — the defining finding of a matured pseudocyst. This wall consists of inflammatory granulation tissue and fibrosis without an epithelial lining. Wall thickness and regularity indicate an uncomplicated pseudocyst; irregular wall thickening suggests infection or malignancy. In acute peripancreatic fluid collections (<4 weeks), this wall has not yet formed.
In the portal venous phase, a homogeneous fluid-density (0-20 HU) collection adjacent to the pancreas or in the peripancreatic space, surrounded by a thin (<2 mm), smooth, enhancing wall. The content contains no solid components or debris. The wall shows homogeneous smooth enhancement.
Report Sentence
A homogeneous fluid-density collection measuring [X×Y] mm, surrounded by a thin smooth enhancing wall, is observed adjacent to the pancreas/in the peripancreatic space, consistent with pancreatic pseudocyst.
On T2-weighted sequences, a markedly hyperintense, homogeneously signaled, well-defined collection. No solid components, debris, or septations are seen within the content. The wall appears as a thin low T2 signal band.
Report Sentence
On MRI, a markedly T2-hyperintense, homogeneous, well-defined collection is observed in the peripancreatic area, consistent with pancreatic pseudocyst.
Demonstration of pseudocyst communication with the pancreatic duct on MRCP — confirms duct injury and is critical for intervention planning (drainage vs surgery). Duct communication may not always be demonstrable but its presence supports the diagnosis.
Report Sentence
MRCP demonstrates/does not demonstrate communication between the pseudocyst and the pancreatic duct; this finding is consistent with duct injury and pseudocyst etiology.
On transabdominal US, an anechoic (or hypoechoic) fluid collection is visualized adjacent to the pancreas. Thin smooth wall, posterior acoustic enhancement, and absence of internal echoes confirm simple fluid. Presence of internal echoes or debris suggests complicated (infected or hemorrhagic) pseudocyst.
Report Sentence
An anechoic fluid collection measuring [X] mm is observed adjacent to the pancreas on US, consistent with pancreatic pseudocyst in the clinical context.
A nodular structure with prominent enhancement in the arterial phase within or near the pseudocyst wall — suggests pseudoaneurysm complication. The splenic artery, gastroduodenal artery, or pancreaticoduodenal arcade are the most commonly involved vessels. Requires urgent evaluation due to life-threatening hemorrhage risk.
Report Sentence
A nodular structure measuring [X] mm with prominent arterial phase enhancement is observed within/near the pseudocyst wall, suggesting pseudoaneurysm complication; urgent CTA/angiography is recommended.
Criteria
Thin smooth wall, homogeneous fluid content, no signs of infection, no pseudoaneurysm, no compression of adjacent organs.
Distinct Features
Conservative follow-up may suffice if asymptomatic and <6 cm. Most show spontaneous resolution (especially <4 cm). EUS-guided drainage or surgical cystogastrostomy is performed for symptomatic or enlarging pseudocysts.
Criteria
Clinical: fever, leukocytosis, abdominal pain. Imaging: wall thickening, internal debris/gas bubbles, peripancreatic inflammatory changes. Purulent fluid and positive culture on aspiration.
Distinct Features
Requires antibiotherapy + drainage. Gas bubbles within the cyst on CT are strong indicators of infection. EUS-guided or percutaneous drainage is the preferred intervention. Surgical drainage/necrosectomy is performed for inadequate response.
Criteria
High-density content (>30 HU) or T1-hyperintense signal on MRI — intracystic hemorrhage. Due to pseudoaneurysm rupture or vascular erosion from pancreatic enzyme digestion.
Distinct Features
Pseudoaneurysm should be investigated — source artery identified on CTA. Active hemorrhage requires emergent angiographic embolization or surgical intervention. Sentinel clot sign (high-density clot within pseudocyst) may indicate the hemorrhage source.
Distinguishing Feature
Walled-off necrosis (WON) is a collection with heterogeneous content (fluid + solid necrotic debris) developing after necrotizing pancreatitis. Pseudocyst has HOMOGENEOUS fluid content without solid components/debris. This distinction directly affects treatment approach — WON may require necrosectomy while pseudocyst is treated with simple drainage.
Distinguishing Feature
Branch duct IPMN is multilocular cystic (grape-like), contains thin septa, may harbor mural nodules, and does not require pancreatitis history. Pseudocyst is unilocular, smooth-walled, without septa, and accompanies pancreatitis history. Cyst fluid CEA (high in IPMN, low in pseudocyst) and amylase (high in pseudocyst) levels are distinguishing.
Distinguishing Feature
Serous cystadenoma shows microcystic 'honeycomb' pattern, central fibrous scar, and sunburst calcification; no pancreatitis history. Pseudocyst is a unilocular smooth-walled collection with pancreatitis history. Demographically, serous cystadenoma is more common in older women.
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
3-monthMost pseudocysts (50-70%) show spontaneous resolution; conservative approach is preferred especially for asymptomatic ones <4 cm. Intervention indications: symptomatic (pain, obstruction), >6 cm, enlarging, infected, or complicated (hemorrhage, rupture, pseudoaneurysm). Intervention options: EUS-guided transmural drainage (cystogastrostomy/cystoduodenostomy, first choice), percutaneous drainage (if cyst-stomach distance >1 cm), endoscopic transpapillary drainage (if duct communication exists), or surgery (if other methods fail or are not feasible). Pseudoaneurysm complication requires emergent angiographic embolization.
Most pancreatic pseudocysts resolve spontaneously. Symptomatic, infected, or >6cm pseudocysts require drainage (endoscopic, percutaneous, or surgical). Pseudoaneurysm complication carries life-threatening hemorrhage risk. Differential diagnosis from cystic neoplasm is important.