Extrapancreatic necrotizing pancreatitis with viable pancreas: a previously under-appreciated entity

Background: Necrotizing pancreatitis is generally considered to involve the pancreatic parenchyma in all patients, and, as an extension of the necrotic process, the peripancreatic tissues as well. We identified a subgroup of patients in whom the necrotic process involves apparently extrapancreatic tissues alone (EXPN), as opposed to the usual combined parenchymal and peripancreatic necrosis (PN). Study Design: The objective of this study was to compare clinical courses of EXPN and PN. Data were reviewed on 82 consecutive patients with necrotizing pancreatitis treated operatively between 1983 and 1997. The extent of pancreatic parenchymal necrosis (expressed as percent of pancreas based on contrast-enhanced CT and operative findings) was estimated in 62 patients. Diagnosis of EXPN required normal enhancement of entire pancreas on dynamic CT and operative documentation of viability of the gland. Results: Twelve patients (19%) had EXPN and 50 (81%) had PN. Gender, age, body mass index, etiology of pancreatitis, prevalence, and type of infection were similar between groups, but APACHE-II scores on admission were less in EXPN (6 ± 2 versus 10 ± 1, p = 0.02). Patients with EXPN required fewer reoperative necrosectomies (0.7 versus 3.2, p = 0.009) and did not develop pancreatic or gastrointestinal fistulas (0 versus 19 patients) or hemorrhage (0 versus 8 patients). ICU stays were similar, but hospital stays in EXPN were shorter (29 ± 6 versus 54 ± 5 days, p = 0.01) and mortality was less (8% and 20%, p < 0.001). Conclusions: Necrotizing pancreatitis manifesting as EXPN is not rare. EXPN is a less aggressive form of necrotizing pancreatitis, locally and systemically, and signifies a better prognosis.