Nonoperative management of pancreatic pseudocysts. Problems in differential diagnosis

Risk factors and nomogram for pancreatic pseudocysts in chronic pancreatitis: A cohort of 1998 patients

BACKGROUND AND AIM

Pancreatic pseudocyst is a common complication of chronic pancreatitis. The identification of risk factors and development of a nomogram for pancreatic pseudocysts in chronic pancreatitis patients may contribute to the early diagnosis and intervention of pancreatic pseudocysts.

METHODS

Patients with chronic pancreatitis admitted to our center from January 2000 to December 2013 were enrolled. Cumulative rates of pancreatic pseudocysts after the onset of chronic pancreatitis and after the diagnosis of chronic pancreatitis were calculated. Patients were randomly assigned, in a 2:1 ratio, to the training and validation cohort. Based on the training cohort, risk factors were identified through Cox proportional hazards regression model, and nomogram was developed. Internal and external validations were performed based on the training and validation cohort, respectively.

RESULTS

With a total of 1998 patients, pancreatic pseudocysts were detected in 228 (11.41%) patients. Age at the onset of chronic pancreatitis, smoking, and severe acute pancreatitis were identified risk factors for pancreatic pseudocysts development while steatorrhea and pancreatic stones were protective factors. Incorporating these five factors, the nomogram achieved good concordance indexes of 0.735 and 0.628 in the training and validation cohorts, respectively, with well-fitted calibration curves.

CONCLUSION

The nomogram achieved an individualized prediction of pancreatic pseudocysts development in chronic pancreatitis. It may help the early diagnosis and management of pancreatic pseudocysts.

Current status of endotherapy for chronic pancreatitis

Chronic pancreatitis is associated with varied morphological complications, including intraductal stones, main pancreatic ductal strictures, distal biliary strictures and pseudocysts. Endoscopic therapy provides a less invasive alternative to surgery. In addition, extracorporeal shockwave lithotripsy improves the success rate of endoscopic clearance of intraductal stones. However, recent data from randomised trials have shown better long-term outcomes with surgical drainage for obstructive pancreatic ductal disease. In patients with distal biliary strictures, stent insertion leads to good immediate drainage, but after stent removal, recurrent narrowing is common. Endoscopic drainage of pancreatic pseudocysts has excellent outcome and should be accompanied by pancreatic ductal stenting when a ductal communication is evident. In those who remain symptomatic, endoscopic ultrasonography-guided coeliac plexus block may provide effective but short-term pain relief. In this review, we present the current evidence for the role of endotherapy in the management of patients with chronic pancreatitis.

Endoscopic diagnosis and treatment of pancreatic cysts

Pancreatic cystic neoplasms have emerged as an important new opportunity for many disciplines to participate in the diagnosis and management of early pancreatic neoplasia. With an increase in an understanding of these lesions and their potential for malignant transformation, there has been a dramatic increase in the frequency of diagnosis. We critically examined the literature on diagnostic methods for pancreatic cystic lesions over the past 5 years. The methods of endoscopic pancreatic pseudocyst drainage and clinical outcomes are also discussed. Morphologic studies of cystic lesions using cross-sectional imaging or endoscopic ultrasound have a low diagnostic rate. Cyst fluid analysis with the use of tumor markers (eg, carcinoembryonic antigen) increases the accuracy of diagnosis. The management of cystic lesions is heavily dependent on the type of cyst, the neoplastic potential, and the risk of surgery. The traditional therapy is pancreatic resection and not cyst enucleation. In contrast to cystic neoplasms, pseudocysts are localized collections of inflammatory fluid that mimic cystic neoplasms. The fluid collections arise from chronic pancreatitis and ductal leaks. Because pseudocysts have no neoplastic potential, they can be drained rather than resected. Drainage can be safely accomplished with external catheters or endoscopically with internal catheters. As we learn more about the pathophysiology of the various cystic lesions, treatment will be tailored to the specific cyst lesion. Endoscopic ultrasound has an important role in the characterization of pancreatic cystic lesions and helps in selection of the optimal treatment modality.

Cystic tumors of the pancreas

Cystic tumors of the pancreas are less frequent than solid lesions and are often detected incidentally, as many of these lesions are small and asymptomatic. However, they may be associated with pancreatitis or have malignant potential. With advancements in diagnostic imaging, cystic lesions of the pancreas are being detected with increasing frequency. Many lesions can cause a pancreatic cyst, most being non-neoplastic while approximately 10% are cystic tumors, ranging from benign to highly malignant tumors. With increasing experience it is becoming clear that the prevalence of pseudocyst among cystic lesions of the pancreas is lower than usually presumed. A presumptive diagnosis of pseudocyst based on imaging appearance alone can cause a diagnostic error, and neoplastic cysts of the pancreas are particularly susceptible to this misdiagnosis, which can result in inappropriate treatment. Cystic tumors of the pancreas are formed by serous or mucinous structures showing all stages of cellular differentiation. According to the WHO classification, they can be subdivided on the basis of their histological type and biological behavior into benign tumors, borderline tumors, and malignant tumors. Cystic pancreatic tumors can be subdivided into peripheral (serous cystadenomas, mucinous cystic tumors, solid and papillary epithelial neoplasms, cystic islet cell tumors), which do not communicate with the main pancreatic duct, and ductal tumors (mucinous tumor), according to their site of origin. On the basis of imaging criteria alone, it can be very difficult to differentiate non-tumoral cystic lesions from neoplastic ones. The management of these patients is complex, and it is important to correlate imaging findings with knowledge of the patient’s symptoms and of the natural history and predictors of malignancy in pancreatic cysts.

Endoscopic drainage of pancreatic fluid collections and pancreatic necrosis

PFCs are heterogeneous, with different underlying pathology and pathophysiology. Each type of PFC is amenable to drainage, although not in every patient. Collections with only a fluid component that have either apposition to the gastric or duodenal wall demonstrated by CT or communication with the main pancreatic duct demonstrated by pancreatography can be drained endoscopically using transmural or transpapillary approaches, respectively. Collections containing significant amounts of solid debris that are treated endoscopically require placement of an irrigation system to evacuate solid debris. Endoscopists considering endoscopic therapy of a pancreatic collection must identify the type of collection being drained and exclude masqueraders of PFCs such as cystic neoplasms. EUS-guided drainage, if available, may decrease the complications of bleeding and perforation during transmural entry of PFCs. Refinement in endoscopic techniques to improve the safety and studies comparing the efficacy of endoscopic therapy with that of other drainage methods are needed.

MR cholangiopancreatography: evaluation of common pancreatic diseases

In the evaluation of common pancreatic diseases, MRCP is a noninvasive alternative to ERCP. Ductal anatomy can be ascertained without risk of complications. MRCP is valuable in defining common anatomic variants, determining the state of the pancreatic duct in pancreatitis, and characterizing neoplasms, especially combined with other MR imaging sequences. With the advent of MRCP, techniques requiring endoscopy and percutaneous access are largely reserved for histologic diagnosis and treatment, or for cases in which MRCP fails to establish a diagnosis.