Choledochal cysts can be categorized into ve types [54, 57]. Type I represents about 50 to 80% of all choledochal cysts, type II 2%, type III 1 to 4%, type IV 15–30%, type V 20%. Type I choledochal cyst can be classied into three additional phenotypes. Type Ia is a cystic dilation of the entire extrahepatic biliary tree that does not involve the intrahepatic ducts. Often the gallbladder and cystic duct will arise from a dilated common bile duct. Type Ib represents a focal segmental dilation of the extrahepatic biliary tree. Type Ic represents a fusiform dilation of the entire extrahepatic biliary tree that involves an intrahepatic duct. Type II choledochal cysts are a saccular diverticulum on the common bile duct. Type III choledochal cysts are also called choledochoceles, and these represent a cystic dilation of the intramural portion of the distal common bile duct that often will bulge into the duodenum. Type IV includes types IVa and IVb. Type IVa is the second most common choledochal cyst and it is represented by an intrahepatic and extrahepatic dilation of the biliary ducts. Type IVb represents multiple dilations of only the extrahepatic biliary tree. Type V choledochal cyst, also known as Caroli’s disease, represents multiple dila­tions of the intrahepatic biliary ducts. This anatomic anomaly is often associated with congenital hepatic brosis which can present with cirrhosis and is termed Caroli’s syndrome [58].

Management of choledochal cysts has changed considerably over time. Several decades ago, initial management consisted of a cyst enterostomy. However, this was associated with recurrence of symptoms and a high risk of malignancy within the remaining in situ cyst wall several decades later. There was an observed malignancy rate of nearly 30% in patients who had previously undergone a cyst enterostomy for the management of a choledochal cyst [62]. Complete excision of the biliary cyst was then recommended and reconstructed or diverted biliary tree was subsequently

At the time of endoscopy, a duodenal follicular lymphoma can be found as either a solitary or multiple nodular masses [69]. These can present as a polypoid lesion, and they are usually between 1 and 5mm in size. As the masses grow, they can become ulcerated which can make endoscopic sampling easier. Multifocal disease is not uncommon with lesions located elsewhere in the jejunum or ileum [70]. On histologic evaluation, most follicular lymphomas of the duodenum are low grade [71]. On microscopy, these appear as well-circumscribed germinal centers with no visible macrophages and without mantle cell zones. Sheets of lymphoid cells that contain irregular nuclei are often present, and the lymphoma will involve the mucosa and submucosa [70]. The immunophenotype is similar to other low-grade follicular lymphomas and these will express CD20, CD10, BCL–6, BCL–2 and lack expres­sion for CD5, CD23, CD43, BCL–1, and T-cell markers [72]. Often these lympho­mas will have a low Ki-67 rate [72].

Endoscopic duodenal resection of lesions and polyps is a complex topic. This is due to the variety of pathology encountered in the duodenum, their proximity to the ampulla, and the unique anatomical considerations within the duodenum including its robust blood supply, thin muscle layer, and scope positioning. In addition, the management of lesions will vary depending on the presence or absence of polyposis syndromes [1]. Careful consideration and thought must be given to each case prior to scheduling a patient for endoscopic resection.

Pre-procedural discussion will include thorough discussion of risks, benets, and alternatives to the procedure. The patient’s comorbidities, surgical history, and med­ications should be reviewed prior to the procedure. Anticoagulant and antiplatelet agents should be held according to society guidelines based on risk of bleeding [2]. The sedation plan should be discussed with the patient and anesthesiologist (if applicable).