Pancreatic pseudocyst

Introduction to pancreatic pseudocyst Pancreatic cysts include true cysts, pseudocysts, and cystic tumors. True cysts include congenital simple cysts, polycystic disease, dermoid cysts, retention cysts, etc. The inner wall of the cyst is covered with epithelium, and the cystic tumor has cystic adenoma and cystic carcinoma. The wall of the pseudocyst is composed of fibrous tissue and is not covered with epithelial tissue. Clinically, pancreatic cysts are most common with pseudocysts. basic knowledge The proportion of illness: 0.002% Susceptible people: no special people Mode of infection: non-infectious Complications: pancreatic abscess jaundice diarrhea shock

Causes of pancreatic pseudocyst

Acute pancreatitis (75%):

Clinical pathology analysis showed that about 75% of cases of pseudocysts were caused by acute pancreatitis, about 20% of cases occurred after pancreatic trauma, 5% of cases were caused by pancreatic cancer, and one group reported 32 cases of pseudocysts, of which 20 cases After acute pancreatitis, 3 cases occurred after abdominal trauma, 8 cases had no clear cause, and 1 case was formed after compression of pancreatic fibrosarcoma. In 20 cases after acute pancreatitis, the earliest cyst was One week after the onset, the latest is 2 years after the onset, and most of them are between 3 and 4 weeks after the onset of the disease.

Extravasation of blood and pancreatic juice (10%):

The blood and pancreatic juice enter the peripancreatic tissue, or enter the cyst formed by the small omental sac in rare cases. The difference between the pseudocyst and the true cyst is that the latter occurs in the pancreas, the cyst is in the pancreas, and the sac is inside. It is composed of glandular ducts or acinar epithelial cells; the former is a cyst formed by encapsulation of effusions in the wall surrounding the pancreas, and there is no epithelial cells in the cyst wall, so it is called a pseudocyst.

Other factors (8%)

Tumors, parasitic infections, trauma, etc. can also induce the disease.

Pathogenesis

Howard and Jorden classify pancreatic cysts according to the etiology of cyst formation:

1 pseudocyst after inflammation: seen in acute pancreatitis and chronic pancreatitis.

2 pseudo-cysts after trauma: seen in blunt trauma, penetrating trauma or surgical trauma.

3 tumor-induced pseudocyst.

4 parasitic pseudocyst: caused by aphids or cysticercosis.

5 idiopathic or unexplained.

Inflammation of the pancreas caused by pancreatic inflammation or trauma, pancreatic juice and blood accumulate around the pancreas, in the omentum and stomach, and in the small omentum, which can stimulate the surrounding tissues and make the connective tissue proliferate. If no pus infection, it can form a In the fibrous wall, animal experiments show that the formation of the pseudocyst wall takes 4 weeks, and it takes at least 6 weeks in the human body. The typical pseudocyst is in communication with the main pancreatic duct. This pancreatic cyst has continuous secretion pressure of pancreatic juice. The ground expands around and continues to exist.

About 80% of pseudo-pancreatic cysts are single-sized, usually about 15cm in diameter and less than 3cm in size. The larger ones have reported a volume of 5000ml. The liquid in the capsule is alkaline, with protein, mucus, cholesterol and red blood cells. The color is not the same, it can be clarified yellow liquid, but also can be a chocolate-like turbid liquid. Although the amylase content is increased, generally no activated enzyme exists.

The wall of the pseudocyst can be adhered due to the inflammatory reaction; the surface often has necrotic tissue attached; due to the formation of granulation tissue, the wall of the capsule is continuously thickened, and the cyst can develop in all directions during its expansion, such as activated pancreas Enzyme enters the sac and invades the blood vessels on the wall of the capsule, which can cause intracapsular hemorrhage. Becker reported that when the cyst is infected, the fatal cyst ruptures due to pancreatic enzyme invasion into the blood vessels and the cyst wall, and the bleeding is 70% to 90%. Sexual cysts, especially pancreatic head cysts, can erode the digestive tract to form internal hemorrhoids. Invading the splenic artery of the pancreatic tail cyst can cause intra-abdominal hemorrhage. Large pseudocysts can compress adjacent organs and cause oppressive symptoms.

It is generally believed that pancreatic pseudocysts are more common in the pancreas and tail, but in recent years, due to the widespread use of B-mode ultrasound imaging, the incidence of pseudocysts in the pancreas has increased significantly. Sugawa and Walt report that 50% of pseudocysts are located. Pancreatic head.

When the pancreas is inflamed or (and) the pancreatic duct is damaged, the pancreatic juice and effusion can spread along the posterior peritoneal space to form an ectopic pseudocyst. For example, the mediastinal cyst can be formed through the transverse medial septum to form the mediastinal cyst or even form the neck. Cysts; downwards can form groin or genital cysts along the left and right lumbar space.

Pancreatic pseudocyst prevention

The key to preventing this disease is to make early diagnosis of acute pancreatitis or pancreatic injury, and take corrective measures early. Once diagnosed, surgery should be scheduled. Diet is mainly fruit juice, millet pumpkin porridge, steamed bread, choose digestible foods, eat enough carbohydrates and protein-based foods, and have enough vegetables and fruits to supplement vitamins and minerals. Do not eat greasy food, do not overeating.

Pancreatic pseudocyst complications Complications pancreatic abscess jaundice diarrhea shock

(1) Secondary infection: This is the most common and most serious complication of pseudocysts. The patient's condition deteriorates rapidly and severe toxemia occurs. At this time, if it is not timely, it often develops into pancreatic abscess and sepsis. Almost without cause of death.

(2) Pancreatic ascites: The pancreatic juice in the pseudocyst leaks into the abdominal cavity from the fistula or rupture, and the peritoneum can cause ascites. The lymphatic vessels around the pancreas can cause lymphatic extravasation, which can also cause ascites. The normal peritoneum can absorb a large amount of liquid, but in In pancreatic ascites, due to cellulose exudation, fibrous tissue hyperplasia, inflammatory cell infiltration and elastic fiber degeneration, the fluid cannot be absorbed in a large amount and accumulate in the abdominal cavity.

(C) pancreatic pleural effusion: about 50% of pancreatic pleural effusion and pancreatic pseudocysts coexist, the pancreatic juice inside the cyst, such as through the lymphatic vessels of the diaphragm, diffused into the chest cavity, stimulate the pleura or cyst and the chest cavity to form a fistula, you can Cause pleural effusion, pleural effusion on the left side.

(D) bleeding bleeding: is a rare but most dangerous complication of pseudocyst, bleeding can be due to:

1 pseudocyst rupture in the blood vessels.

2 cysts invade the gastrointestinal wall.

3 Complicated esophageal varices due to portal vein or splenic vein obstruction.

4 cysts invade the biliary tract and bleed.

5 pseudoaneurysm rupture, in the intracapsular hemorrhage, the cysts increase sharply, and can hear the sound of blood flow, so if the cyst suddenly increases and there is a sign of systemic blood loss, angiography should be performed in time, often requiring emergency surgery, including The cyst is removed or the cyst is ligated and the bleeding is performed, and the cyst is drained.

(5) Patients with spleen involvement in pancreatic pseudocysts may have spleen involvement at the same time, possibly due to:

1 pancreatic pseudocyst erodes the spleen.

2 The digestive effect of pancreatic juice overflowing from the cyst on the spleen.

3 Inflammation of the pancreatic tissue occurs in the spleen.

4 complicated with splenic vein thrombosis, liquefaction in the infarct area of the spleen, in this case, early spleen resection should be performed, and as far as possible for distal pancreatectomy.

(6) Cyst rupture and perforation Pancreatic pseudocyst can spontaneously perforate or break into the adjacent viscera, often complicated by gastrointestinal bleeding, pancreatic pseudocysts break into the stomach, duodenum, colon, etc., not necessarily symptoms, at this time It is not necessarily dangerous to the patient. On the contrary, it can provide effective drainage. However, if the cyst breaks into the abdominal cavity, the mortality rate is extremely high. In this case, the patient often has shock and the mortality rate is 18% to 80%.

(7) Others

1 Astragalus: due to pseudocyst compression of the common bile duct can cause obstructive jaundice.

2 diarrhea: pseudo-pancreatic cysts can sometimes cause severe diarrhea.

Pancreatic pseudocyst symptoms Common symptoms Nausea back pain Abdominal pain Cystic mass Low fever Diarrhea Pancreatic calcification Transverse colon Transposition calcified nodules

In patients with acute pancreatitis or pancreatic trauma, persistent upper abdominal pain, nausea and vomiting, weight loss and fever, abdominal fistula and cystic mass should first consider the possibility of pseudo-pancreatic cyst formation.

A few pseudocysts are asymptomatic. Only in the B-ultrasound examination, the clinical symptoms of most cases are caused by cysts pressing adjacent organs and tissues. About 80% to 90% of abdominal pain occurs. Most of the pain is in the upper abdomen. Related to the location of the cyst, often radiated to the back, the pain occurs due to cyst compression of the gastrointestinal tract, posterior peritoneum, celiac plexus, and cyst and pancreas itself caused by inflammation, nausea, vomiting about 20% to 75%; appetite Decreased about 10% to 40%, weight loss is about 20% to 65% of cases, fever is often low fever, diarrhea and jaundice are relatively rare, cysts if the compression of the pylorus can lead to pyloric obstruction; compression of the duodenum can cause ten Bipolar stagnation and high intestinal obstruction; compression of the common bile duct can cause obstructive jaundice; compression of the inferior vena cava caused by symptoms of inferior vena cava obstruction and lower extremity edema; compression of the ureter can cause hydronephrosis, etc., mediastinal pancreatic pseudocyst can be heart, Pulmonary and esophageal compression symptoms, chest pain, back pain, difficulty swallowing, jugular vein engorgement, etc., if the pseudocyst extends to the left groin, scrotum or rectal uterine crypt, etc. There are symptoms of rectal and uterine compression.

At the time of physical examination, about 50% to 90% of patients have a mass in the upper abdomen or the left quarter. The mass is spherical, the surface is smooth, and there is no nodular sensation, but there may be fluctuations and the mobility is not large. Often tenderness.

Examination of pancreatic pseudocyst

(1) Determination of blood urease amylase: The pancreatic enzyme in the cyst can be found in hematuria after absorption through the cyst wall, causing a mild to moderate increase in amylase in serum and urine, but it has been reported in about 50% of cases of amylase Can not rise, generally in the pseudocyst caused by acute pancreatitis, serum amylase often continues to rise, and chronic pancreatitis is often normal.

(B) B-ultrasound: B-ultrasound is a simple and effective means of diagnosing pancreatic pseudocysts. Typical cases can be found in the upper abdomen, a clear position, a certain range of liquid dark areas, B-ultrasound identification kit Blocks and cysts are particularly helpful, and the correct rate of diagnosis of pancreatic pseudocysts can reach 73% to 91%. Dynamic ultrasound exploration can understand the change of cyst size. In addition, under the guidance of B-ultrasound, it can be used as a capsule puncture. The liquid is biochemically and cytologically examined.

(C) CT examination: the pancreatic pseudocyst on the CT scan is a round or oval density uniform reduction zone with a smooth edge. For example, CT examination shows a gas-liquid plane, indicating the formation of an infectious abscess.

(4) X-ray examination: X-ray barium meal examination also has a localization value for pancreatic pseudocyst. In addition to excluding the lesions in the gastrointestinal cavity, the cysts can be seen on the surrounding organs and the signs of displacement, such as in the stomach. There is a large pseudocyst, and the expectorant can show that the stomach is moving forward, the stomach can be compressed, and the pseudocyst of the pancreas can widen the duodenum and the transverse colon can be displaced upwards or downwards. A flat slice can reveal pancreatic calcification shadows.

(5) ERCP: The presence and location of cysts can be determined by ERCP, and it is helpful to distinguish from pancreatic cancer. In septic cysts, ERCP shows cyst filling; main pancreatic duct obstruction, obstructive end is tapered or interrupted; The general canal is under pressure; in the non-communicating cyst, the pancreatic duct branches are compressed and the local branches are not filled, but about half of the pseudocysts do not communicate with the main pancreatic duct, so the pancreatic duct angiography can not be denied diagnosis, ERCP can also check Whether or not there is a fistula, but ERCP can promote secondary infection or spread inflammation, so cases that have been confirmed in the diagnosis should not be classified as routine examinations.

(6) Selective angiography: Selective angiography has a positive diagnostic value for pseudocysts. It can show the lesions, the cyst area is avascular area, and the adjacent vessels are displaced and deformed. This test can correctly diagnose the blood vessels. In the case of invasion, determine whether there is bleeding or hemorrhagic source, and whether there is any pseudoaneurysm in the cyst wall. Angiography is used to judge whether the pseudocyst invades the spleen, which is more valuable than B-ultrasound and CT.

Diagnosis and differentiation of pancreatic pseudocyst

According to the medical history, clinical manifestations and laboratory data is not difficult to make a diagnosis.

Pancreatic pseudocysts must be differentiated from pancreatic abscess and acute pancreatic cellulitis. Patients with abscesses often have signs of infection. Occasionally, pseudocysts can manifest as weight loss, jaundice, and gallbladder that is painlessly swollen, often first considered pancreatic cancer. A CT scan showed that the lesion was fluid, suggesting that a pancreatic cyst can be correctly diagnosed. Proliferative cysts, as well as pancreatic cystadenoma or cystadenocarcinoma, account for about 5% of pancreatic cystic lesions, and should be differentiated from pancreatic pseudocysts before surgery. The exact differential diagnosis is mainly determined by biopsy. The pseudocyst of the head of the pancreas should be differentiated from the liver and right renal cyst. The tail cyst should be differentiated from the left hepatic cyst, the left renal cyst, and the spleen cyst.

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