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Pancreatic pseudocysts are common sequelae of acute pancreatitis or chronic pancreatitis, and the most common cystic lesion of the pancreas. They are important both in terms of management and differentiation from other cystic processes or masses in this region.
The following are the latest terms according to the updated Atlanta classification to describe fluid collections associated with acute pancreatitis 10,11:
- fluid collections in interstitial edematous pancreatitis
- fluid collections in necrotizing pancreatitis
Pancreatic pseudocysts are frequently found on imaging follow-up of pancreatitis, and may in themselves be asymptomatic for some time. Presentations attributable to a pseudocyst include:
- mass effect
- biliary obstruction
- gastric outlet obstruction
- secondary infection
Pseudocysts occur from disruption of pancreatic duct structure with resulting leakage and accumulation of pancreatic juice resulting in hemorrhagic fat necrosis. They are not lined by epithelium (thus, “pseudocysts”), rather a severe inflammatory reaction results in encapsulation of the cyst by fibrosed granulation tissue. This usually takes 4-6 weeks 8,9. In approximately 50% of cases, the cyst retains a communication with the pancreatic duct 2. Such cysts are more problematic to treat, and are more likely to recur.
- acute or chronic pancreatitis (most common)
- pancreatic trauma
- iatrogenic, e.g. post partial gastrectomy 12
Pseudocysts are fluid-filled oval or round collections with a relatively thick wall. They can be multiple and are most commonly located in the pancreatic bed. However, they can be found anywhere from the groin to the mediastinum and even in the neck, having ascended in the retroperitoneum via the diaphragmatic hiatuses into the mediastinum 5.
It is not possible to reliably distinguish infected from non-infected pseudocysts on imaging alone 9.
Abdominal radiographs are often not sensitive in the workup for a pancreatic pseudocyst. However, if the cyst is large, it may demonstrate a gastrocolic separation sign which suggests fluid at the peripancreatic region and into the lesser sac 15.
Hypoechoic or anechoic collections, with dependent low-level echoes representing debris, are often seen 8.
Pseudocysts appear as well-circumscribed, usually round or oval peripancreatic fluid collections of homogeneously low attenuation, that are usually surrounded by a well-defined enhancing wall 10.
According to the revised Atlanta classification, pseudocysts contain no non-liquefied components within the fluid collection 10.
- hypointense (fluid signal) center
- wall demonstrates mild early enhancement, which progressively becomes more intense 7
- hyperintense (fluid signal)
- layering or dependent debris, highly specific 6
Treatment and prognosis
Although pancreatic pseudocyst may regress on its own and requires no further treatment, interventions are required in selected cases, particularly those complicated with infections, large size causing mass effect symptoms such as gastric outlet obstruction, bowel obstruction, hydronephrosis and biliary obstruction, diameter increasing in size or greater than 5 cm, recurrence following previous resection or aspiration, and persistent symptoms 14,16,17.
Treatment options include:
- open surgical debridement, or cystenterostomy with a Roux-en-Y jejunal loop 3
- endoscopic drainage into the stomach (or duodenum) termed a cyst-gastrostomy 3
- percutaneous drainage
- remains somewhat controversial, although increasingly accepted 1,2
- many centers report high safety and efficacy 1
- critics raise concern regarding potential reaccumulation and fistula formation to the skin (especially in patients with severe pancreatitis) 4
- octreotide infusion: decreases amount of pancreatic secretions
Cysts that do not communicate with the pancreatic duct usually do not recur and are unlikely to create fistulae 2.
General imaging differential considerations include:
- cystic lesions of the pancreas
- choledochal cyst (especially for ultrasound)
mesenteric duplication cysts
- very thin walls
- peripancreatic collection of acute pancreatitis
- will not be round, but rather take on the contours of the space in which they are located
- pseudocysts take ~4 weeks to form
- gastric duplication cyst 13
- nonpancreatic pseudocyst18
- cystic fluid with low levels of amylase or lipase in the cystic fluid.
- 1. Vansonnenberg E, Wittich GR, Casola G et-al. Percutaneous drainage of infected and noninfected pancreatic pseudocysts: experience in 101 cases. Radiology. 1989;170 (3): 757-61. Radiology (abstract) - Pubmed citation
- 2. Lucey BC, Kuligowska E. Radiologic management of cysts in the abdomen and pelvis. AJR Am J Roentgenol. 2006;186 (2): 562-73. doi:10.2214/AJR.04.1051 - Pubmed citation
- 3. Werner J, Feuerbach S, Uhl W et-al. Management of acute pancreatitis: from surgery to interventional intensive care. Gut. 2005;54 (3): 426-36. doi:10.1136/gut.2003.035907 - Free text at pubmed - Pubmed citation
- 4. Fotoohi M, D'agostino HB, Wollman B et-al. Persistent pancreatocutaneous fistula after percutaneous drainage of pancreatic fluid collections: role of cause and severity of pancreatitis. Radiology. 1999;213 (2): 573-8. Radiology (full text) - Pubmed citation
- 5. Karantanas AH, Sandris V, Tsikrika A et-al. Extension of pancreatic pseudocysts into the neck: CT and MR imaging findings. AJR Am J Roentgenol. 2003;180 (3): 843-5. AJR Am J Roentgenol (full text) - Pubmed citation
- 6. Macari M, Finn ME, Bennett GL et-al. Differentiating pancreatic cystic neoplasms from pancreatic pseudocysts at MR imaging: value of perceived internal debris. Radiology. 2009;251 (1): 77-84. doi:10.1148/radiol.2511081286 - Pubmed citation
- 7. Semelka RC. Abdominal-pelvic MRI. Wiley. (2006) ISBN:0471692735. Read it at Google Books - Find it at Amazon
- 8. Bluth EI. Ultrasound, a practical approach to clinical problems. George Thieme Verlag. (2000) ISBN:0865778612. Read it at Google Books - Find it at Amazon
- 9. Kim YH, Saini S, Sahani D et-al. Imaging diagnosis of cystic pancreatic lesions: pseudocyst versus nonpseudocyst. Radiographics. 25 (3): 671-85. doi:10.1148/rg.253045104 - Pubmed citation
- 10. Thoeni RF. The revised Atlanta classification of acute pancreatitis: its importance for the radiologist and its effect on treatment. Radiology. 2012;262 (3): 751-64. doi:10.1148/radiol.11110947 - Pubmed citation
- 11. Banks PA, Bollen TL, Dervenis C et-al. Classification of acute pancreatitis-2012: revision of the Atlanta classification and definitions by international consensus. Gut. 2012;62 (1): 102-11. doi:10.1136/gutjnl-2012-302779 - Pubmed citation
- 12. Surgical Pathology of the GI Tract, Liver, Biliary Tract and Pancreas: Expert Consult. Saunders. ISBN:1416040595. Read it at Google Books - Find it at Amazon
- 13. Davies S, Morris-Stiff G, Lewis MH. Gastric duplication cyst mimicking a pancreatic pseudocyst in a patient with chronic pancreatitis. (2008) International journal of surgery (London, England). 6 (6): e70-1. doi:10.1016/j.ijsu.2007.03.002 - Pubmed
- 14. Daniel J. Deziel, Richard A. Prinz. Drainage of Pancreatic Pseudocysts: Indications and Long-Term Results. (1996) Digestive Surgery. 13 (2): 101. doi:10.1159/000172415
- 15. Rivera Reyes HH, Moreno G. [Evaluation of the gastrocolic space in 100 cases of acute pancreatitis (author's transl)]. (1975) La Prensa medica mexicana. 40 (11-12): 341-5. Pubmed
- 16. Kim YH, Saini S, Sahani D, Hahn PF, Mueller PR, Auh YH. Imaging diagnosis of cystic pancreatic lesions: pseudocyst versus nonpseudocyst. (2005) Radiographics : a review publication of the Radiological Society of North America, Inc. 25 (3): 671-85. doi:10.1148/rg.253045104 - Pubmed
- 17. Ferrucci JT, Mueller PR. Interventional approach to pancreatic fluid collections. (2003) Radiologic clinics of North America. 41 (6): 1217-26, vii. Pubmed
- 18. Yang D, Jung D, Kim H et al. Retroperitoneal Cystic Masses: CT, Clinical, and Pathologic Findings and Literature Review. RadioGraphics. 2004;24(5):1353-65. doi:10.1148/rg.245045017 - Pubmed