Benign Enterogenous Cyst of the Pancreas

James Majeski, MD, PhD, Department of Surgery, East Cooper Hospital, Mt. Pleasant, SC; Joseph Harmon, MD, Department of Pathology, Roper Hospital, Charleston, SC

South Med J. 2000;93(3) 

In This Article

Discussion

Enterogenous cysts of the pancreas are rare. Only four previous cases have been reported.[3,4,5,6] Lyon[3] reported the first case of an enterogenous cyst of the pancreas. The pancreatic cyst was contained within an abnormal lingula of pancreatic tissue, which was dissected free on a vascular pedicle containing the aberrant duct and resected without sacrificing the main body of the gland. The wall of the cyst contained smooth muscle, and the inner wall was lined with gastric epithelium. In the second case, reported by Pilcher et al,[4] the tail of the pancreas was partially replaced by multiple cystic structures that extended into the hilum of the spleen. The cyst wall contained smooth muscle, and the inner wall was lined with ciliated epithelium. Pins et al[5] reported the third case of an enterogenous cyst. The peripancreatic unilocular mass in the tail of the pancreas was resected by a distal pancreatectomy. The cyst lining was composed of a pseudostratified, ciliated epithelium with admixed mucous and goblet cells. The wall of the cyst consisted of a double layer of smooth muscle and an external fibrous capsule. The fourth case was reported by Kohzaki et al.[6] The unilocular cyst was adherent to the anterosuperior portion of the head of the pancreas. The cyst wall was lined by ciliated simple columnar and pseudostratified epithelium. Bands of smooth muscle fibers and mucin-secreting bronchial glands were found beneath the epithelium. Cholesterol crystals and calcifications were also found in the cyst wall.

The uniqueness of the enterogenous cyst found in this case was the presence of ciliated respiratory epithelium, transitional epithelium, and gastric mucosa on the inner lining of the cyst. The cyst had a bilayered smooth muscle wall and a serosal surface in at least one area. Portions of the cyst wall appeared calcified on CT scan. This combination of histologic findings is unique from the four previous reports of benign enterogenous cysts of the pancreas.

While ciliated epithelium is most commonly seen in the respiratory tract, it is found in the fetal esophagus from gestational week 10 to 20.[7] The entire foregut is lined by multipotential endodermal cells.[4] Consequently, these multipotential endodermal cells account for the presence of ciliated epithelium, transitional epithelium, and gastric mucosa in duplication cysts of the stomach, ileum, cecum, and pancreas.[8,9,10] Presence of these multipotential endodermal cells also explains the presence of gastric, pancreatic, and gastrointestinal epithelium reported in other cases of bronchial cysts. In the cases reported by Pilcher et al[4] Pins et al,[5] and Kohzaki et al,[6] the best explanation is that the cyst was created during canalization of the pancreatic duct lumen. During early embryogenesis, the pancreatic duct contains foregut-derived multipotential cells capable of differentiating into several cell types.

The initial sonographic finding in our patient's case revealed the cystic pancreatic wall to have scattered calcifications. The CT scan showed the enterogenous cyst at the junction of the body and tail of the pancreas. No internal septations were identified. The main pancreatic duct was not dilated. The initial appearance of this cyst resembled a pancreatic cystic tumor extending anteriorly and caudally into the lesser sac. The possibility of a cystic neoplasm was further supported by the lack of a history of alcohol abuse and radiographic studies revealing a normal biliary tract. The differential diagnosis included a serous or mucinous cystic neoplasm. The presence of calcifications in the cyst wall lent support for the diagnosis of pancreatic cystadenoma.[2]

It is important to differentiate an enterogenous cyst from a pancreatic pseudocyst or a benign or malignant cyst of the pancreas. Treatment of an enterogenous cyst of the pancreas is simple surgical excision with preservation of the pancreas.

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