State-of-the-art endoscopic treatment of walled-off postnecrotic pancreatic collection

Clinical History

Young adult with past episode of severe gallstone-related acute pancreatitis (AP) treated at another hospital with endoscopic sphincterotomy and subsequent laparoscopic cholecystectomy. Ten months later, complains of persistent upper abdominal pain and fullness.
Laboratory assays revealed mild anaemia, serum lipase and amylase at upper normal limits.

Imaging Findings

The ovoid-shaped radiographic (Fig. 1) opacity had corresponding CT (Fig. 2) finding of a vast, nonenhancing fluid-attenuating collection centred in the pancreatic region, with discernible peripheral wall and dependent debris; this walled-off pancreatic necrosis (WOPN) following necrotising AP exerted mass effect on the stomach and spleno-portal venous system.
Endoscopic ultrasound-guided treatment included cystogastrostomy, dilatation and positioning of fully-covered transmural gastrocystic stent, pigtail stents and nasocystic drainage for lavage (Fig. 3). After treatment, the WOPN showed marked size decrease, mixed gaseous and fluid content; the adjacent posterior wall of gastric antrum became thickened with submucosal oedema (Fig. 4).
Further EUS-guided treatment included nasocystic tube removal, trans-stent necrosectomy with polypectomy snare and Dormia basket, leaving pigtail stents.
A month later, the patient developed signs and symptoms of superinfection, which corresponded to CT (Fig. 5) findings of mild increase of size and wall thickness of treated WOPN, which ultimately required repositioning of nasocystic tube and trans-Wirsung drainage (Fig. 6).

Discussion

The updated Atlanta classification classifies chronic pancreatic fluid collections (CPFCs) developing over 4 weeks after AP as either pseudocysts or walled-off pancreatic necrosis (WOPN). Resulting from fluid leakage during interstitial oedematous AP, the former show at CT homogeneously fluid attenuation and an identifiable, well-defined wall. Conversely, the latter are secondary to necrotising AP and appear radiologically inhomogeneous due to the presence of debris from progressive liquefaction of necrotic tissue. Alternatively, CPFCs may occasionally develop after surgery or trauma [1, 2].
During the last decade there has been a progressive shift in management. Traditionally, indications for operative treatment included CPFCs measuring at least 6 cm in size and causing pain, discomfort, jaundice or gastric outlet obstruction. Nowadays, management is increasingly proactive due to awareness of risk of possible complications such as superinfection, haemorrhage and rupture [3-6].
In the past, symptomatic pseudocysts were managed by percutaneous drainage, open or laparoscopic cystogastrostomy, and WOPN required surgical debridement plus necrosectomy; however, particularly in the latter entities surgery was burdened by considerable morbidity, prolonged hospitalisation and non-negligible mortality. Currently, endoscopic ultrasound (EUS)-guided transmural drainage (EUS-GTD) has emerged as the preferred, minimally invasive treatment, which provides direct access to the CPFC without traversing the abdominal wall such as in percutaneous drainage. Endoscopically puncture under sonographic visualisation allows avoiding varices along the intended track; transmural stents and/or nasocystic tube are placed after balloon dilatation of the cystogastrostomy. EUS-GTD achieves technical and clinical success in respectively 97% and 91% of pseudocysts, with lower morbidity and cost, and allows faster recovery and improved quality of life compared to surgery; the latter is currently reserved for those patients with unfavourable anatomy. Furthermore, fully-covered self-expanding and specifically designed metal stents allowed easier passage of the endoscope for performing necrosectomy mechanically and with hydrogen-peroxide infusion [3, 6-9].
In general, complications develop in a mean 15% (range 0-50%) of patients, and include bleeding from erosion injury of pancreatic vessels, superinfection and stent migration; the latter may result from insufficient anchorage between the stent, the gastric wall and the progressively collapsing PFC. Since gas results from cysto-gastric communication, infection is generally suggested by increasing thickness of the enhancing wall. Risk factors for complications include too-early EUS-GTD after AP, and treatment of WOPN and abscesses (risk 40%) compared to pseudocysts (9.2%). Recurrent CPFCs from stent displacement or obstruction occur in 5.7-17.7% of patients and may require retreatment [3, 6-9].

Differential Diagnosis List

Final Diagnosis

Walled-off postnecrotic pancreatic collection treated by endoscopic ultrasound-guided cystogastrostomy and necrosectomy.

URL:	https://www.eurorad.org/case/14809
DOI:	10.1594/EURORAD/CASE.14809
ISSN:	1563-4086