**10. Chronic pseudocysts**

In the chronic pancreatitis parenchymal fibrosis and ducts, dilatation can cause chronic pseudocysts [53]. Chronic pancreatitis encompasses various complications. Most frequent are pseudocyst formation, mechanical obstruction of the duodenum, or common bile duct. Pseudocysts occur in about 10% of patients with chronic pancreatitis. There are great patho‐ logical differences from acute and chronic pseudocysts. The first usually develop from peripancreatic fluid accumulations that cause the pseudocysts formation in the setting of acute pancreatitis. On the contrary, chronic pseudocysts develop as a result of ductal disruptions [53]. Pseudocysts may be single or multiple, various in size. In fact, the pancreatic pseudocysts generally are caused and long maintained by some leaks from the pancreatic ducts that give the constant filling by pancreatic secretions [50]. A long history and clinical evolution of chronic pancreatitis can give usually a clear diagnostic direction. Chronic recurrent abdominal pain characterizes the clinical appearance of the disease. The other common symptoms are nausea and vomiting, early satiety. Jaundice can occur in 10% of patients with a slow start due to bile duct compression by the pseudocyst or the pancreatic flogosis. The imaging examinations, particularly EUS, allow, beside the cystic lesion, to detect the characteristic parenchymal features of chronic pancreatitis: the damage of the pancreatic duct system, parenchymal fibrosis, and calcifications [53]. The Rosemont classification [58] of chronic pancreatitis, based on EUS findings, identifies major criteria such as main pancreatic duct calculi and lobularity and minor criteria with cysts, dilated ducts >3.5 mm, irregular pancreatic duct contour, and dilated side branches >1 mm.

The surgical treatment of chronic pancreatitis should be based on the clinical and pathological scenario: two types of surgical procedures with the aim of improving or eliminating ductal hypertension by intestinal anastomotic drainage can be performed [53]. Resectional proce‐ dures allow eliminating the areas of chronic inflammation frequently in the head of the pancreas. A late complication of chronic pancreatitis encompasses evident ductal dilatation. The incidence of these chronic pseudocysts is high: 20–40% [59]. The pseudocysts can be connected with adjacent organs such as stomach or duodenum. Consequently, endoscopic approach can be performed with mini‐invasive intent, cystogastrostomy, or duodenocystos‐ tomy [60]. The morbidity of this procedure is 3–11%, without mortality. The treatment of chronic pseudocysts by drainage through the duodenal papilla and ductal system also has been proposed by endoscopy. This procedure with ERCP allows putting in place the transpa‐ pillary endoprotesis as drainage. In addition, the transluminal stones removal and/or litho‐ tripsy can be possible, if intraductal stones are present [60–62]. The surgical management has shown good results in the treatment of chronic pseudocysts, pancreatic duct dilatation with stenosis, and stones. The Puestow procedure and its modifications of Partington and Rochelle [63, 64] are the standard surgical drainage methods in chronic pancreatitis with pseudocyst and/or dilated ducts. These interventions involve the anastomosis between dilated main duct and pseudocystic wall with a Roux‐en‐Y loop of jejunum. The results show low morbidity (<10%) and low mortality (<1%) with relief from abdominal pain in 85–90% of the patients [65– 67]. Sometimes, with a dilated pancreatic duct, a fibrotic inflammatory mass may be present in the pancreas. In these cases, the interventions that couple drainage and resective procedures defined "hybrid" can be chosen: Beger, Frey interventions, and some variants [67–69].

### **11. Indeterminate pancreatic cystic lesions**

Another pathological characteristic of acute pseudocysts is the close connections with various adjacent intestinal organs (stomach, duodenum, and small intestine) according to the ana‐

Drainage of the pseudocysts by endoscopic technique has been proposed [55, 56]: this is performed by creating a small opening between the cyst and the stomach. The disadvantage of this techniques is incomplete drainage with recurrence of pseudocysts and infections because the communication can be small and in site not declive [53, 57]. The surgical cystodi‐ gestive anastomosis can employ the more adjacent intestinal organ (stomach or duodenum or small intestine) and can perform cystogastrostomy or cystojejunostomy or cystoduodenosto‐

For cysts located in the body or tail of pancreas, the cystojejunostomy or cystogastrostomy is performed depending on the development of the cyst above or under the mesocolon. For pseudocysts located on the head of the pancreas, cystoduodenostomy is usually performed. The same surgical procedures can be performed with a laparoscopic approach with the

In the chronic pancreatitis parenchymal fibrosis and ducts, dilatation can cause chronic pseudocysts [53]. Chronic pancreatitis encompasses various complications. Most frequent are pseudocyst formation, mechanical obstruction of the duodenum, or common bile duct. Pseudocysts occur in about 10% of patients with chronic pancreatitis. There are great patho‐ logical differences from acute and chronic pseudocysts. The first usually develop from peripancreatic fluid accumulations that cause the pseudocysts formation in the setting of acute pancreatitis. On the contrary, chronic pseudocysts develop as a result of ductal disruptions [53]. Pseudocysts may be single or multiple, various in size. In fact, the pancreatic pseudocysts generally are caused and long maintained by some leaks from the pancreatic ducts that give the constant filling by pancreatic secretions [50]. A long history and clinical evolution of chronic pancreatitis can give usually a clear diagnostic direction. Chronic recurrent abdominal pain characterizes the clinical appearance of the disease. The other common symptoms are nausea and vomiting, early satiety. Jaundice can occur in 10% of patients with a slow start due to bile duct compression by the pseudocyst or the pancreatic flogosis. The imaging examinations, particularly EUS, allow, beside the cystic lesion, to detect the characteristic parenchymal features of chronic pancreatitis: the damage of the pancreatic duct system, parenchymal fibrosis, and calcifications [53]. The Rosemont classification [58] of chronic pancreatitis, based on EUS findings, identifies major criteria such as main pancreatic duct calculi and lobularity and minor criteria with cysts, dilated ducts >3.5 mm, irregular pancreatic duct contour, and

The surgical treatment of chronic pancreatitis should be based on the clinical and pathological scenario: two types of surgical procedures with the aim of improving or eliminating ductal hypertension by intestinal anastomotic drainage can be performed [53]. Resectional proce‐

tomical site where the pseudocyst develops [53].

advantage of the minimal invasiveness [53].

**10. Chronic pseudocysts**

dilated side branches >1 mm.

my [52, 53].

106 Challenges in Pancreatic Pathology

Cystic lesions of the pancreas today are an important diagnostic challenge. In each case the specific diagnosis must be defined: pseudocysts, SCNs, MCNs, IPMNs, and SPPNs are the most common lesions. Perhaps more important is to establish the malignant potential and the objective data of a neoplastic degeneration. The diagnostic procedures to choose should be geared toward minimally invasiveness. Imaging examinations are at the first line: CT, MRI, MRCP, and PET are minimally invasive and have shown various degrees of sensitivity and specificity. ERCP and EUS–FNA are invasive and can give some useful information. If imaging findings allow the certain diagnosis of specific lesion of which is well known the malignant potential and the characteristic features of malignant evolution, the therapeutic choices (surgery or observation) are enough defined. Moreover, clinical symptomatic picture adds further certainty to the treatment program. There are also, among cystic pancreatic neoplasms, some well‐defined diagnoses characterized by imaging and clinical data for which the management is uncertain and debatable. In summary, there are two problems in the manage‐ ment of cystic pancreatic lesions. Firstly, the difficulty in the diagnostic definition and/or in the detection of malignancy; moreover, also, in some cases, the positive diagnosis of the lesions is characterized by particular pathological and clinical features that cause uncertainty in the choice of treatment between surgery, observation program, and for how many times the control can be prolonged.

All clinical, pathological, and imaging findings with also analysis of cyst fluid examination by EUS‐FNA have been reported above in the detailed report of each cystic lesions of the pancreas. This knowledge crucial for the diagnosis and management should be integrated by the classification that separates pancreatic cystic lesions in two categories. There are pancreatic cysts benign, not premalignant, such as SCNs, pseudocysts, lymphoepithelial cysts, and lymphangioma, and pancreatic cysts premalignant and malignant such as MCNs, IPMNs, SPPNs, and CPENs [70]. Roughly, the first conclusion can be the indication of surgical resection for premalignant lesions and observation for benign or indolent lesions. The indeterminate cystic lesions can be located between the cysts frankly benign such as pseudocysts or serous cystadenoma or lymphangioma and, on the other hand, the cystic lesions frankly malignant or with clear findings of malignant evolution such as MD‐IPMNs, IPMNs associated with invasive carcinoma, MCNs with increased size, cyst‐wall irregularity, and intracystic solid regions. In the indeterminate cystic lesions, the management choices can be debatable and uncertain. In this group, small cysts with not certain diagnosis, small BD‐IPMNs, or MCNs can be considered. Characteristic in this setting is the asymptomatic pancreatic cyst inciden‐ tally detected on abdominal CT. The improvement of an unclear diagnosis can be achieved with MRI and MRCP. If the data obtained with these examinations are not conclusive (e.g., main duct <1 cm; thick cyst wall size >2 cm), the diagnostic process can continue with invasive procedure such as EUS‐FNA. The detection of nodule or solid mass or main duct >1 cm and cytology positive for malignancy is crucial for the surgical resection. In the patients without these diagnostic data, the conservative option marked by periodic controls with CT or MRI or EUS (repeat the control test in 6 months) can be evaluated [70]. In the patients with clear diagnosis (CT, MRI, EUS, and clinical data), serous cystadenoma asymptomatic can be followed with periodic imaging control with MRI or CT (repeat the control test in 1 year); if symptomatic, overall in young patient (<65 years), surgery should be considered. Patients with MD‐IPMNs, mixed‐type IPMNs, SPPNs, and MCNs should be proposed for surgical resection. BD‐IPMNs characterized by main pancreatic duct >1 cm, cystic lesion in the head of pancreas, jaundice, solid component, main duct with thickened wall, and mural nodule, which are features concerning malignancy, can undergo surgical resection, if, without these findings, CT, MRI, and EUS (repeat the control test in 6 months) may be followed conservatively.

There is almost unanimously consensus [32, 71] for surgical indications in patients with MCNs, SPPNs, MD‐IPMNs, and mixed‐type IPMNs. Patients with serous cystadenoma should be directed to conservative management. Surgery can be proposed only in symptomatic patients or if the diagnosis is uncertain. Patients with BD‐IPMN can be observed also if the size lesion is more than 3 cm unless there are features concerning for potential malignancy.
