الفهرس 
EMBRYOLOGY OF THE PANCREASOnly 14 pages are availabe for public view
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Abstract
P
ancreatic cysts are fluid-filled structures in and around the pancreas. Pancreatic cysts include inflammatory lesions, low-grade neoplasms and malignant neoplasms.
Accurate assessment of cystic neoplasms of the pancreas is imperative before selecting available treatment options, such as surgical resection, drainage, or conservative therapy (Linder et al., 2006).
Although possible etiologies of pancreatic cysts are numerous, the most common are pseudocysts and cystic tumors (David et al., 2010).
The first step in evaluation is to differentiate pseudocysts from cystic neoplasms, since inflammatory pseudocysts are the most common lesion and are benign in nature. Once a pancreatic pseudocyst has been excluded, attention should be focused on the differential diagnosis among the types of cystic neoplasms. The most important diagnostic strategy is to differentiate SCA from mucinous types including MCN and IPMN, and this is due to the benign nature of SCA. Although serous cystadenocarcinomas have been described, they are so rare that serous cystic neoplasms should be managed as benign disease (Strobel et al., 2003).
The first step in evaluation is to differentiate pseudocysts from cystic neoplasms, since inflammatory pseudocysts are the most common lesion and are benign in nature. Once a pancreatic pseudocyst has been excluded, attention should be focused on the differential diagnosis among the types of cystic neoplasms. The most important diagnostic strategy is to differentiate SCA from mucinous types including MCN and IPMN, and this is due to the benign nature of SCA. Although serous cystadenocarcinomas have been described, they are so rare that serous cystic neoplasms should be managed as benign disease (Strobel et al., 2003).
Mucinous lesions on the other hand are potentially or overtly malignant lesions, and generally surgery is the treatment of choice. Based on their location within the ductal system, IPMNs are classified as main-duct or branch-duct type and several studies have suggested that the latter have a more favorable prognosis (Allen et al., 2006).
Identifying a subset of branch-type IPMNs with better prognosis that can be followed without resection would be the final important step(Sugiyama et al., 2003).
The combination of clinical history and character-istics along with imaging findings may increase the diagnostic accuracy in the discrimination of pancreatic cysts. Because the results of conventional imaging and endosonography are not completely satisfactory in distinguishing different lesions and in estimating their malignant potential, EUS-guided cyst fluid analysis of cytology, chemistry, and tumor markers has been increasingly performed to provide additional information (Chul et al., 2008).
The Pancreatic Cyst DNA Analysis (PANDA) study was a very important prospective study that took place in many centers across the United States. The study authors found that K-ras muta¬tion was relatively specific for a mucinous cyst, with a specificity rate of more than 90% (William et al., 2009).
Pancreatic pseudocysts require treatment when they cause symptoms, produce complications, or have reached a size exceeding 5 cm and do not regress after 6 weeks of observation. In the last-named situation, treatment is indicated because complications can otherwise be expected (Markus et al., 2009).
The endoscopic and minimally invasive therapeutic procedures for the drainage of pancreatic pseudocysts are superior to open surgical techniques with respect to their success rates, morbidity, and mortality, but they cannot always be performed. In making treatment decisions, it is important to recall that 50% of pancreatic pseudocysts do not require any intervention and can be successfully managed by a wait-and-watch approach.
Laparoscopic and endoscopic drainage have comparable success rates, while that of transcutaneous drainage is somewhat worse. Thus, the choice of technique depends very heavily on the experience of the treatment center.
All MCNs are thought to progress ultimately to malignancy, and most middle-aged patients with mucinous cystadenomas may develop overt malignancies during their lives (Tanaka et al., 2006).
The prognosis of patients with overt or invasive mucinous cystadenocarcinoma is poor; even after complete resection, the 5-yr survival rate reaches only 5–33%. In contrast, IPMN differs from MCN in that treatment can vary from observation to surgery depending on its clinicopathologic characteristics. Histopathology of IPMN is known to range broadly from benign lesion and borderline malignancy to invasive carcinoma, and prognostic factors that correlate with histopathologic findings have been identified (Salvia et al., 2007).
from these, resection has been recommended for all main-duct IPMNs while asymptomatic branch-duct IPMNs less than 30 mm in cyst size without mural nodules may best be followed by conservative management.
Aggressive strategy with surgical removal by laparoscopy, if possible, may be considered for indeterminate cystic lesions in the body and tail portion of the pancreas. Larger cysts are more likely to cause symptoms in the future even if they are currently asymptomatic, and thus surgery would be recommended for a large cyst found in a young patient (Chul et al., 2008).
The emerging use of agents to eliminate cysts is the most exciting new area of this field (The possibility of injecting agents into a cyst for ablation or elimination of the cyst lining, rather than removing the cyst through surgery). Several stud¬ies have looked at how well ethanol works in terms of eliminating pancreatic cysts. Other investigators have used chemotherapy injections into the cyst cavity in addition to ethanol, and their early results have been very promising (William et al., 2009).