Pancreatic pseudocyst

Introduction to pancreatic pseudocyst Pseudodocystofthepancreas (pseudocystofthepancreas) is a cyst formed by pancreatic juice, blood and necrotic tissue on the basis of pancreatic inflammation, pancreatic necrosis, trauma, proximal pancreatic duct obstruction and other pancreatic parenchyma or pancreatic duct rupture. The wall of the capsule is composed of granulation tissue or fibrous tissue without lining of epithelial cells. basic knowledge The proportion of the disease: the disease is usually secondary to patients with pancreatitis, the incidence rate is about 0.003%-0.008% Susceptible people: no special people Mode of infection: non-infectious Complications: acute diffuse peritonitis jaundice gastrointestinal bleeding edema portal hypertension

Cause of pancreatic pseudocyst

(1) Causes of the disease

1. Howord and Jorden classification method This method is the most commonly used classification method. The pseudocysts are divided into 5 categories, mainly pseudo-cysts after inflammation and trauma, and others are rare.

(1) pseudocysts after inflammation: including acute and chronic pancreatitis, accounting for about 80%, the most common with alcoholic pancreatitis; followed by gallstone, most of China's gallstones; other causes such as hyperlipidemia.

(2) Pseudocysts after trauma: about 10%, including blunt trauma, penetrating trauma and surgery.

(3) Idiopathic or unexplained.

(4) pseudocyst caused by tumor: it is caused by pancreatitis caused by obstruction of the pancreatic duct.

(5) Parasitic pseudocysts: such as aphid and hydatid cysts, which are caused by parasites causing local necrosis of the pancreas to form cysts.

2. Urgent, chronic classification The pseudocyst is divided into acute and chronic, which is helpful for the choice of treatment.

(1) acute pseudocyst: acute pancreatitis or pancreatic trauma caused by pancreatic juice or exudate accumulation, surrounded by serosal membrane, mesenteric and peritoneum and other cysts, early cystic fluid is easy to absorb, but with the thickening of the cyst wall And fibrosis, the cyst becomes difficult to absorb.

(2) Chronic pseudocyst: occurs after chronic pancreatitis, no acute exacerbation of pancreatitis, caused by expansion of small pancreatic duct or acinus caused by thicker pancreatic duct obstruction, epithelial cell atrophy, forming a "retention" cyst And gradually increase, can exceed the scope of the pancreas, but also form a thicker wall, the cyst fluid is not easy to absorb.

However, some people think that the cyst formed after the onset of acute pancreatitis is acute in less than 6 weeks and chronic in more than 6 weeks.

3. Classification of Yeo and Sarr In recent years, clinical studies have found that even if the causes of pseudocysts are the same, the effects of treatments and even the prognosis vary greatly. This is mainly due to the different pathological types. The traditional concept of pseudocysts is more general. When the doctor is treating, there is no difference between whether the cyst is connected with the pancreatic duct and whether there is necrotic tissue in the capsule, and a large part of the acute pancreatitis pancreatic fluid is also treated as a pseudocyst. The result is of course different, Yeo and Based on the above questions, Sarr proposed a classification method that would help to select treatment options, compare efficacy and judge prognosis.

(1) pancreatic true-pseudocyst: refers to cysts caused by various causes of pancreatic duct rupture, pancreatic juice extravasation, cyst and pancreatic duct traffic, cystic fluid trypsin and trypsin concentration increased.

(2) Pancreatic pseudo-pseudocyst: It is the accumulation of inflammatory exudate caused by pancreatic or peripancreatic inflammation and trauma. The cyst does not communicate with the pancreatic duct. The cystic fluid trypsin and trypsin are not elevated, and no necrosis is required. organization.

(3) Pancreatic heaotic cyst: is a local cystic change and exudate accumulation after pancreas and peripancreatic tissue necrosis caused by necrotizing pancreatitis. The capsule contains pancreatic parenchyma or peripancreatic, retroperitoneal fat. Necrosis, with or without communication with the pancreatic duct, the concentration of pancreatic enzyme trypsin or trypsin may or may not increase.

(two) pathogenesis

In the past, the pancreatic pseudocyst was used as a single cyst, and the traditional expectational countermeasures were adopted. With the in-depth study on the occurrence, development and pathological changes of acute and chronic pancreatic pseudocysts, the principle of treatment has been updated.

Pancreatic juice containing a variety of digestive enzymes exudates from the necrotic pancreatic tissue to the peritoneal space around the pancreas, causing an inflammatory reaction and cellulose deposition, forming a fibrous envelope after one to several weeks, and the posterior peritoneum constitutes the anterior wall of the cyst, or The pancreatic juice directly infiltrates into the small omental sac. Winslow pores are often closed by inflammation. The cysts are formed in the small omentum. Sometimes the pancreatic juice enters other parts along the interstitial space to form cysts of special parts, such as the mediastinum, the spleen, and the kidney. And pseudo-pancreatic cysts in the squirrels.

About 80% of pseudo-pancreatic cysts are single-shot, often communicating with the pancreatic duct. For example, pancreatic duct visualization can be seen by injecting contrast medium into the cyst. The cyst fluid contains amylase, esterase, protease, chymotrypsin, decarboxylase, etc. Pancreatic digestive enzymes and albumin, mucin, cholesterol, inflammatory debris, etc., sometimes contain blood, the pancreatic duct endocrine pressure does not exceed 2.94 kPa (30cmH2O), when the pressure inside the capsule is too large, the pancreatic juice stops exuding, but Due to the high content of cystic fluid protein, there is continuous infiltration of water, cysts can gradually increase, pseudo-pancreatic cysts are more common in the tail of the body, cyst size varies greatly, small diameter 4 ~ 5cm, large contains thousands of ml of liquid, For cysts that last longer, the activity of trypsin in the cyst fluid often disappears.

Acute pancreatic pseudocyst is also called acute pancreatic fluid retention. In acute pancreatitis, especially acute necrotizing pancreatitis, pancreatic juice extravasation, self-digestion causes pancreas itself and peripancreatic tissue necrosis, liquefaction plus pancreatic juice and inflammatory exudation Peripancreatic retention and retention, the pancreatic duct rupture after injury, the sputum contains a lot of blood, the contents of the capsule are often brownish black due to hemorrhage and tissue necrosis, the amylase is generally higher, and the wall of the capsule is the visceral peritoneum that stimulates the surrounding organs by inflammation. And the inflammatory fibrous tissue produced by the omentum, without pancreatic epithelial cell coverage, no true capsule, the wall is actually the surrounding cavity and the greater omentum, for the above reasons,

1 The wall of the capsule needs to be mature for a certain period of time, generally about 6 weeks. Only when a relatively firm fiber wall is formed can the cystic gastrointestinal anastomosis be safely performed, otherwise anastomotic leakage may occur.

2 The cyst wall should not be forcibly separated during surgery to avoid bleeding and gastrointestinal rupture. The contents of the capsule containing a large amount of digestive enzymes have many local hazards: A. Secondary infection and easy destruction of intestinal mucosal barrier, endogenous infection B. Corrosion of adjacent organs to cause perforation; C. Trypsin destroys the elastic fibers of the vessel wall, causing rupture of blood vessels, causing massive bleeding in the capsule; D. Huge cysts compressing surrounding organs, leading to obstructive jaundice and gastrointestinal obstruction; E. Sudden increase in intracapsular pressure plus external force factors can cause rupture and form acute diffuse peritonitis.

Chronic pancreatic pseudocyst often occurs on the basis of chronic pancreatitis, leading to the formation of localized or diffuse fibrosis and necrotic changes in the pancreatic parenchyma, resulting in obstruction of the pancreatic duct, poor excretion of pancreatic juice, and eventually the formation of pancreatic pseudocyst, often occurring in Pancreatic parenchyma and pancreatic pericarp, generally small, the contents of the cyst are mostly pancreatic juice, grayish white, due to the long course of disease, the wall of the capsule is a gradually proliferating fibrous tissue layer, often thicker and more mature, once the cystic hemorrhage, the cyst will also Rapid expansion increases, chronic pancreatic cysts are often associated with clinical manifestations of pancreatic endocrine and exocrine insufficiency, chronic gastrointestinal symptoms and diabetes.

Pancreatic pseudocyst prevention

Correct and effective treatment of primary disease (urgent, chronic pancreatitis, pancreatic trauma, pancreatic tumor, parasite, etc.), to prevent pancreatic parenchyma or pancreatic duct rupture caused by pancreatic juice, blood and necrotic tissue and other packages to form cysts.

Pancreatic pseudocyst complications Complications acute diffuse peritonitis jaundice gastrointestinal hemorrhage edema portal hypertension

Complications of pancreatic pseudocysts are more common in acute pancreatic pseudocysts.

1. Intracapsular hemorrhage Many thick blood vessels in the peripancreatic and upper abdomen often form part of the wall of the capsule, such as the left gastric vein, the right gastric vein, the spleen arteriovenous vein, etc. The blood vessel wall is activated by pancreatic enzyme and infection erosion. Sudden rupture and bleeding, the patient may suddenly have severe persistent abdominal pain, abdominal mass sharply increased, and there are signs of irritation, often showing symptoms of internal bleeding, and soon into shock state, B-ultrasound can be found in the capsule is a strong echo blood clot After the hemorrhage, the intracapsular pressure suddenly increases, which can cause gastrointestinal spasm of the cyst, and massive bleeding of the digestive tract. If the patient is generally allowed, he can perform percutaneous selective angiography, find the bleeding site and perform blockage or emergency surgery. After internal hemorrhage, hemorrhage blood vessels are ligated, and 2 to 3 channels are ligated away from the lesion. If the patient's condition is extremely poor, in order to save lives, a long gauze strip may be used to fill the skein. After the cessation of bleeding for 3 to 4 days, the gauze is gradually extracted.

2. After the cyst rupture cyst rupture, the abdominal mass suddenly disappears. If the cyst fluid enters the abdominal cavity, continuous abdominal pain may occur, causing acute diffuse peritonitis. Emergency drainage and external drainage of the cyst, such as wearing the gastrointestinal tract, often accompanied Diarrhea, a small number of gastrointestinal bleeding can occur, if the amount of bleeding is not large, you can first non-surgical treatment, after 6 weeks, then decide further treatment options.

3. Intracapsular cysts complicated by infection, usually appear abdominal pain, fever, white blood cells and other signs, acute pancreatic pseudocyst secondary infection and acute severe pancreatitis necrosis combined with infection is difficult to distinguish, especially within 2 weeks, treatment should be immediately drained For suspicious patients, B-ultrasound or CT-guided puncture smear examination and bacterial culture, it is helpful for diagnosis. Once the infection is determined, such as cysts are single-chamber and the cystic fluid is not thick, you can choose puncture catheter drainage, such as surgery. External drainage should be chosen.

4. The cyst compresses the surrounding cyst and compresses the stomach and duodenum or colon. Gastrointestinal obstruction can occur. Compression of the common bile duct can cause obstructive jaundice, compression of the vein or formation of venous thrombosis, the most common is the splenic vein, followed by Is the portal vein and superior mesenteric vein, can form high blood pressure in the stomach and spleen, extrahepatic portal hypertension or duodenal submucosal varices and upper gastrointestinal bleeding; compression of the inferior vena cava leads to edema of both lower extremities, very few can extend to the esophagus Or aortic hiatus, rise to the mediastinum and chest compression of the heart and lungs, affecting circulation and respiratory function, the above situation should be immediately performed drainage decompression surgery.

Pancreatic pseudocyst symptoms Common symptoms Abdominal pain, nausea, upper abdominal pain, abdominal mass, dull pain, bloating, diarrhea, upper gastrointestinal bleeding, jaundice

Pain is the most common symptom, mostly in the upper abdomen, the degree of pain is not heavy, it is dull pain or pain, occasionally radiating to the back or left rib, often loss of appetite, nausea, vomiting, weight loss, sometimes other symptoms are not obvious The above abdominal mass is the main complaint. In a small number of patients, the cyst is compressed by the bile duct and the jaundice appears. About 3/4 of the patients can touch the tumor during the physical examination, mostly in the upper abdomen, the surface is smooth, and there are few capsules due to the tension. Sexy, such as no inflammation, no obvious tenderness, about 10% of patients can be seen with jaundice, serum amylase increased in 30% to 50% of patients.

Examination of pancreatic pseudocyst

About half of the patients have elevated serum amylase and leukocytosis, and bilirubin can be elevated in biliary obstruction. If serum amylase in patients with acute pancreatitis continues to rise for more than 3 weeks, half of the patients may have pseudocysts. A small number of patients have abnormal liver function tests.

X-ray inspection

Including abdominal plain film and gastrointestinal barium meal imaging.

Abdominal plain film: visible gas and colonic gas bubble shift, due to calcification caused by pancreatitis, occasionally the pancreas has patchy calcification, the wall of the capsule shows a curved dense linear shadow.

Gastrointestinal barium meal angiography: depending on the situation, you can use barium meal, barium enema or both methods.

(1) Gastroduodenal type: The cyst is located between the head of the pancreas and the inside of the duodenum. The larger cyst can cause the duodenal ring to expand into a large arc shape, the inner edge is compressed, and the intestinal lumen is narrow. The agent passes slowly, the pyloric region of the stomach and the abdomen of the duodenum move up, and the horizontal and lifting segments of the duodenum are shifted to the left.

(2) Gastric liver type: The cyst is located between the upper edge of the pancreatic body and the stomach and liver, so that the small curvature of the stomach is shifted to the left and left.

(3) Post-stomach type: The cyst is located in front of the pancreas, behind the stomach, and the lateral position shows that the stomach is displaced forward, the distance from the spine is widened, the posterior wall of the stomach is curved, and the stomach cavity is curved and thin. The transverse colon is displaced downward and the spleen is displaced to the left.

(4) Gastric colon type: The cyst is located in the front and the back of the pancreas or the body, which can shift the stomach forward and the transverse colon downward.

(5) Colon mesangial type: The cyst is located at the lower edge of the pancreatic body and extends into the transverse mesenteric membrane, causing the transverse colon to move forward, the descending colon to the left, and the stomach to the upper right.

(6) Stomach and spleen type: The cyst is located between the tail of the pancreas and the stomach and spleen, so that the corpus corpus is displaced to the right. The curved curvature of the edge of the stomach is smooth and the spleen is displaced to the left. The giant cyst can raise the diaphragm. , activities are limited.

The method is simple, about 77% to 86% of cysts have positive performance, which can show the degree of compression of the cyst on the stomach and duodenum and the displacement of the above organs, thereby clearing the relationship between the position of the cyst and the gastrointestinal tract, and The combination of other imaging methods provides an essential basis for the selection of internal drainage methods.

2.B Ultra

A clear circular or elliptical liquid dark area can be found around the pancreas. Most of the interior is clear, a few are scattered in the echo point, and the posterior wall echoes. In this part, the normal pancreas structure generally disappears. In some cases, part of the pancreas is visible. Tissue echo, the rest of the area connected to the liquid dark area can explore the structure of the pancreas, a small number of pancreatic pseudocysts in the liquid dark area has a number of separate light bands, suggesting a multi-room structure, some cysts can detect strong echo and Acoustic imaging should consider calcification or pancreatic duct stones. Larger cysts can show signs of displacement of surrounding organs, blood vessels and bile ducts. The true cysts are generally small, located inside the pancreatic tissue, and generally have normal pancreatic structures around them. Pseudocysts are located in the pancreas. This part usually has no pancreatic tissue echo. The two are not difficult to identify. This method is simple, non-invasive, and low in cost. The accuracy rate is as high as 95% to 99%. It can not only determine the size and position of the cyst, but also Identify the nature of the cyst, the thickness of the cyst wall, the clarity of the capsule, and whether there is a septum between them. Therefore, it should be used as the first choice for pancreatic cysts. It can be examined multiple times and observed dynamically. And determining the timing of surgery and treatment methods.

3.CT

The pseudocyst of the pancreas is close to the water sample. The wall of the capsule is thin and uniform, and there is no strengthening. There is no wall nodule. When there is irregular calcification on the wall or in the capsule, a small sister capsule or papillary nodule can be seen in the capsule wall. Cavity, such as the wall wall nodules found in the posterior capsule wall, there is the possibility of cystic adenocarcinoma. If irregular small bubbles or gas-liquid plane are seen in the capsule, it is a suspicious sign of abscess. When there is bleeding, infection or necrosis in the capsule. When tissue is organized, the density inside the capsule is increased, and its identification mainly depends on the medical history. This method can not only show the location and size of the cyst, but also can determine its nature, and contribute to the identification of pancreatic pseudocyst and pancreatic abscess, pancreatic cystic tumor. In patients with more gas in the capsule or obesity, especially for cysts with a diameter of <5cm, which is difficult to detect by B-ultrasound, CT can obtain better imaging results. In view of the need for equipment for CT, the cost is high and it is harmful to the human body, so it cannot be classified as a pancreas. A routine examination item for a pseudocyst.

4.ERCP

It can show the lesion of pancreatic duct stenosis in chronic pancreatitis, and some cysts can be found to communicate with the pancreatic duct. However, this test has the risk of inducing infection. In recent years, it has not been advocated, and it is generally arranged only in the case of full application of antibiotics before surgery. Next, provide the basis for the choice of surgical methods.

5. Selective angiography

Selective angiography has a positive diagnostic value for pseudocysts. It can show the lesions. The cyst area is avascular area and see the displacement of adjacent vessels. This examination can correctly diagnose the invasion of blood vessels and determine whether there is bleeding. And the source of bleeding, to determine whether there is a pseudoaneurysm in the wall of the capsule.

6. Percutaneous fine needle aspiration cytology

For the identification of cystic fluids, there are still differences on this method of inspection. There are two reasons for dissenting opinions.

1 worry about the cultivation of malignant cells into the peritoneal or puncture pathway;

2 worried that misdiagnosis leads to inappropriate treatment. Therefore, for the diagnosis of pancreatic pseudocysts with clear diagnosis, this test is urgently needed. It is only used for highly suspected pancreatic cystadenocarcinoma. Patients are not suitable for surgery for various reasons and need to make Diagnostic.

Diagnosis and diagnosis of pancreatic pseudocyst

diagnosis

The clinical manifestations of pancreatic pseudocysts are mainly based on the stage of acute or chronic pancreatitis. In acute cysts, the manifestation is the continuation of the condition. The patient is in the case of acute pancreatitis and cannot be improved quickly, fever, upper abdominal distension. Pain and tenderness, lumps, bloating, gastrointestinal dysfunction, etc.; severe complications can occur. In later cases, the pseudocyst wall is mature, and the surrounding inflammatory changes have subsided. The main points of clinical diagnosis include:

1 history of acute pancreatitis;

2 upper abdominal pain and gastrointestinal dysfunction;

3 upper abdominal mass;

4 Urea amylase may or may not increase.

Chronic pancreatic pseudocyst mostly occurs on the basis of chronic recurrent pancreatitis. When the cyst volume is not very large, especially in the tail of the pancreas, the upper abdomen mass is not clinically seen, mainly as symptoms of chronic pancreatitis. Abdominal and low back pain, fat digestive dysfunction, diabetes, etc., upper abdominal pain, chronic pancreatitis, splenomegaly, upper gastrointestinal bleeding, normal liver function is a feature of this disease.

Clinically encountered patients with acute or chronic pancreatitis or upper abdominal injury, upper abdominal pain, fullness, mass, gastrointestinal dysfunction, physical examination can touch the upper abdomen round or elliptical mass, the border is not Clear, more fixed, sac sexy, deep tenderness, you should think of pancreatic cysts, gastrointestinal angiography, B-ultrasound can make a diagnosis, but only diagnosed pancreatic cyst is not enough, for guidance Treatment, should also identify the following issues.

1. It is indeed a pancreatic pseudocyst rather than a true pancreatic cyst. Most of the former have a history of acute or chronic pancreatitis or pancreatic injury, the latter is generally not; B-ultrasound, especially CT, is helpful for identification.

2. Is acute pancreatic pseudocyst, or chronic pancreatic pseudocyst is mostly caused by acute pancreatitis or pancreatic injury, and some are in the stage of acute pancreatitis. In addition to the performance of acute pancreatitis, the activity of blood urease amylase is increased, especially It is the urinary amylase continues to rise, chronic pancreatic pseudocyst mostly occurs on the basis of chronic recurrent pancreatitis, mainly manifested as chronic pancreatitis symptoms, such as low back pain, indigestion, fatty diarrhea and signs of diabetes.

3. The size and location of the pancreatic pseudocyst, whether there is a septum in the sac by gastrointestinal angiography, B-ultrasound, CT examination is not difficult to make a judgment, should also identify the relationship between the cyst and the gastrointestinal tract, accurately measure them The distance between the cysts without septum is the indication for drainage of the puncture catheter. The gap between the cyst and the gastrointestinal tract <1cm is suitable for endoscopic treatment.

4. Whether the wall of the capsule is mature or not has a reference significance, but B-ultrasound and CT show the thickness of the capsule wall is an important basis for selecting the timing of surgery.

5. Whether the cyst and the pancreatic duct are connected, the pancreatic duct has or without stenosis. The acute pancreatic pseudocyst is not necessarily related to the pancreatic duct, no pancreatic duct stenosis, chronic pancreatic pseudocyst and pancreatic duct traffic, and pancreatic duct stricture, ERCP or cyst. Contrast-enhanced examinations provide definitive evidence that external drainage should not be selected for cysts that are concomitant with the pancreatic duct and that pancreatic fistula may occur.

6. Close observation of changes in cysts Once the diagnosis of pancreatic pseudocysts has been determined and a clear judgment has been made on the above five aspects, a preliminary treatment plan can be determined, but the changes in cysts, including size and wall thickness, should be further observed dynamically. , intracapsular density and whether there is intracapsular hemorrhage, infection, sudden increase in cysts, cyst rupture and compression of surrounding organs and other complications, in order to timely correct the treatment.

Differential diagnosis

Pancreatic pseudocyst must be differentiated from pancreatic abscess and acute pancreatic cellulitis. Patients with abscess often have infections. Occasionally, pseudocysts can show weight loss, jaundice and gallbladder that touches painless swelling. For pancreatic cancer, CT scan shows that the lesion is fluid, suggesting that pancreatic cyst can make a correct diagnosis, proliferative cyst, as well as pancreatic cystadenoma or cystadenocarcinoma, accounting for 5% of pancreatic cystic lesions. In the identification of pancreatic pseudocysts, the exact differential diagnosis depends mainly on intraoperative visual observation and biopsy.

Sometimes, especially in the absence of obvious history of pancreatitis or pancreatic trauma, in addition to true cysts and other cysts in the abdomen, the identification of solid masses, should also be differentiated from pancreatic abscess, pancreatic abscess often accompanied by high fever, systemic poisoning symptoms and white blood cell liters High, cystic fluid Gram staining and culture are helpful for diagnosis. If it is purulent cyst fluid, the diagnosis is clear.

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