Causation of Pancreatic Pseudocyst Is the Key Influential Factors for the Success of EUS-Guided Treatment: The Therapeutic Strategy for Pancreatic Pseudocyst Based On Causative Factors

Abstract

Background: Pancreatic pseudocyst (PPc) can be divided into 3 types based on causative factors: type 1, acute post-necrotic pseudocyst; type 2, post-necrotic pseudocyst on chronic pancreatitis; and type 3, chronic pseudocyst (retention). Types 1 and 2 can be classified as post-necrotizing pseudocysts, and with the spread of inflammation outside pancreas, the omental sac that exists between pancreas and stomach itself forms a cystic cavity, resulting in pseudocyst. The gastric wall thus becomes a cystic wall, and EUS-guided pseudocyst drainage (EUS-CD) is safety indicated. Type 3 is basically an intrapancreatic cyst, and because the stomach is separate from cyst, EUS-CD may cause to leak the cyst contents into abdominal cavity. In recent years, a technique to debride/lavage of a cyst by inserting an endoscope via stomach has been reported, but whether it is required in all PPc is unclear. The aim of this study was to clarify the indications for EUS-CD based on causative factors. Methods: 31 patients with PPc >6 cm in diameter, including 7 with type-1, 20 with type 2, and 4 with type 3, were enrolled. As to therapy, the external drainage using a naso-biliary tube was performed to manage infections, the internal drainage using a stent between the cyst and stomach was employed if aspirated contents were serous. With external drainage, the tube was clamped 2 weeks after placement, and it was removed 3 days later if the cyst did not increase. Then, if the cyst increased, internal drainage was employed. (Results) Internal drainage was performed on 1 type-1 and 4 type-2 patients. External drainage was employed on 6 type-1, 16 type-2, and 4 type-3 patients. For these treatments, efficacy of EUS-CD for types 1, 2, and 3 was 57%, 90%, and 50%. In type-1, a small cyst remained in 3 patients who were treated using EUS-CD alone. In addition, in almost type-2, EUS-CD alone was sufficient to achieve favorable results. In 2 type-3, EUS-CD alone was not enough, and surgical treatment was required. Regarding complications, in 1 type-2 patient and 2 type-3 patient, cystic contents leaked into the abdominal cavity during the procedure. (Conclusions) In the treatment of type-1, debridement / lavage of cyst via the stomach are appropriate. In type-2, management using a drainage tube is appropriate. Furthermore, in type-3, management using a drainage tube is pertinent if the cystic wall adheres to the gastrointestinal wall due to inflammation, but no therapy should be sufficient if no inflammation is present because of no adherence between cyst and stomach. The present study was retrospective, but demonstrates the importance of planning therapy based on pseudocyst type.