Unusual Sites of Necrotic Collections in Acute Necrotizing Pancreatitis: Association with Parenchymal Necrosis and Clinical Outcomes

The presence of necrotic collection in acute necrotizing pancreatitis (ANP) at intra-abdominal sites other than the retroperitoneum has not been systematically studied. To investigate unusual sites of necrotic collections at computed tomography (CT) and to evaluate association with pancreatic necrosis and clinical outcomes. This retrospective study comprised of consecutive patients with ANP evaluated between January 2018 and March 2019. Based on CT findings, patients were divided into two groups: collections at unusual sites (small bowel mesentery, mesocolon, omentum, subcapsular collections along liver and spleen, pelvis, anterior abdominal wall, and inguinoscrotal regions) and collections at usual retroperitoneal locations (lesser sac, gastrosplenic location, anterior and posterior pararenal spaces, and paracolic gutters). The differences in CT findings and clinical outcomes (need for drainage, length of hospitalization, intensive care unit admission, surgery, and death) between the two groups were evaluated. A total of 75 patients with ANP were evaluated. There were 25 (33.3%) patients with collections in unusual locations. These included mesentery (n = 17), splenic subcapsular location (n = 7), omentum (n = 6), hepatic subcapsular location (n = 4), anterior abdominal wall (n = 3), pelvis (n = 2), and inguinoscrotal location (n = 1). Compared to patients with collections at usual locations (n = 50), there were no differences in the CT findings except complete parenchymal necrosis (32% vs. 0%, P = .001). There were no statistically significant differences in the clinical outcomes between the two groups. Mesenteric collections are frequent in ANP. The other non-retroperitoneal sites are infrequently involved. There is no association between unusual sites of collection and clinical outcomes.