Pseudocyst

2007-09-07T13:11:00.000-07:00

Pancreatic pseudocyst
From Wikipedia, the free encyclopedia

Classification & external resources
ICD-10
K 86.3
ICD-9
577.2
DiseasesDB
9530
MedlinePlus
000272
eMedicine
med/2674 radio/576
MeSH
D010192

A pancreatic pseudocyst is a circumscribed collection of fluid rich in amylase and other pancreatic enzymes, blood and necrotic tissue typically located in the lesser sac. It has a non-epithelialised lining made of granulation tissue and hence the name pseudocyst (pseudo - false). By contrast, true cysts have an epithelial lining. This is typically a complication of acute pancreatitis, but may also occur following abdominal trauma. Pancreatic pseudocysts account for approximately 75% of all pancreatic masses.

Etiopathogenesis
Acute pancreatitis results amongst other things in the disruption of pancreatic parenchyma and the ductal system. This results in extravasation of pancreatic enzymes which in turn digest the adjoining tissues. This results in a collection of fluid containing pancreatic enzymes, hemolysed blood and necrotic debris around the pancreas. The lesser sac being a potential space, the fluid collects here preferentially. This is called an acute pancreatic collection. Some of these collections resolve on their own as the patient recovers from the acute episode. However, others become more organised and get walled-off within a thick wall of granulation tissue and fibrosis. This takes several weeks to occur and results in a pancreatic pseudocyst.

Investigations
The questions that need to be answered are:

where, how big and how many?
Ss there a communication with the pancreatic ductal system?

Draining such a pseudocyst carries an increased risk of pancreatic fistula.
The most useful imaging tools are:

Ultrasonography - The role of ultrasonography in imaging the pancreas is limited by patient habitus, operator experience and the fact that the pancreas lies behind the stomach (and so a gas-filled stomach will obscure the pancreas).
Computerised tomography - This is the gold standard for initial assessment and follow-up
Magnetic Resonance Cholangio-pancreatography - to establish the relationship of the pseudocyst to the pancreatic ducts

Treatment
A small pseudocyst that is not causing any symptoms may be managed conservatively. However, a large proportion of them will need some form of treatment, The interventions available are:

Endoscopic trans-gastric drainage
Imaging guided percutaneous drainage
Laparoscopic/open cystogastrostomy

Lesser sac
From Wikipedia, the free encyclopedia

The greater sac or general cavity (red) and lesser sac, or omental bursa (blue).

Horizontal disposition of the peritoneum in the upper part of the abdomen. (Lesser sac is outlined in blue in center.)
Latin bursa omentalis
Gray's
subject #246 1156
MeSH
Lesser+Sac
The lesser sac, also known as the omental bursa, is the cavity in the abdomen that is formed by the lesser and greater omentum. Usually found in mammals, it is connected with the greater sac via the epiploic foramen, also known as the Foramen of Winslow. In mammals, it is not uncommon for the lesser sac to contain considerable amounts of fat.
In human anatomy, the wall of the stomach, pancreas and splenic artery[1] are a part of the wall of the lesser sac. If these structures rupture they may leak into the lesser sac.
The lesser sac is embryologically formed from an infolding of the greater omentum. The open end of the infolding, known as the epiploic foramen, is usually proximal to the stomach.

Additional images

Upper part of celom of human embryo of 6.8 mm., seen from behind.

Schematic figure of the bursa omentalis, etc. Human embryo of eight weeks.

Diagrams to illustrate the development of the greater omentum and transverse mesocolon.

Reference
^ Shahani RB, Bijlani RS, Dalvi AN, Shah HK, Samsi AB. Massive upper gastrointestinal haemorrhage due to direct visceral erosion of splenic artery aneurysm. J Postgrad Med 1994;40:220-2. Full Text.

External links
ii/l/LESSER_SAC article at GE's Medcyclopaedia
SUNY Labs 37:09-0100 - "Abdominal Cavity: The Lesser Peritoneal Sac"
SUNY Anatomy Image 8070
Retrieved from "http://en.wikipedia.org/wiki/Lesser_sac"