Patterns of Pathomorphological Changes in Acute Necrotizing Pancreatitis

Acinar necrosis is the basic microscopic sign of acute necrotizing pancreatitis (ANP). Microcirculation disorder is one of the major factors in the pathogenesis and morphogenesis of ANP besides free radicals and damage of enzymatic origin. This study is dedicated to the description of microscopic changes in the pancreatic stroma in ANP, which leads to destruction of the exocrine pancreas with a putative mechanism of endocrine function preservation. This study has been carried out on histological samples of pancreas from 224 patients with ANP. Histological staining was performed with hematoxylin-eosin (H&E), Masson, Gomori methods, and PAS. Microscopy was performed with magnifications of 40×, 100×, and 400×. Vascular endothelial desquamation, stasis, and sludge are typical changes in microcirculation observed in early stages of ANP. Initially, parietal circular intravascular microthrombosis accompanied by endothelial desquamation as early as stromal swelling occurs with no detectable necrosis. Residual stroma appears between areas of necrosis and intact pancreatic tissue. Mucoid swelling is first seen in the perivascular spaces extending to the parenchyma and changing into fibrinoid imbibition causing further necrosis. Reticulin argyrophilic backbone surrounding the pancreatic acini and small ducts decompose. Pancreatic structures, which may be preserved in necrotic tissue, include nerves, major ducts, and Langerhans islets. 1. Introduction Necrosis and tissue degradation are the basic microscopic signs of acute necrotizing pancreatitis (ANP). These changes can be focal or diffuse. We believe that the microcirculation disorder is one of the strongest factors in the pathogenesis and morphogenesis of ANP besides free radicals and of enzymatic origin. 2. Aim This study is dedicated to investigation and description of microscopic changes in the pancreas in ANP which leads to the destruction of the exocrine pancreas, changes in the pancreatic stroma, and a presumable mechanism of preservation of endocrine function. 3. Materials and Methods This study has been carried out on histological samples of pancreas from 224 patients with ANP. All these patients were operated at the Kyiv Center for Hepatopancreatobiliary Surgery (named after V. S. Zemskov) from 1997 through 2004. Postmortem examinations of autopsy tissue were performed in 21 of the 224 patients. The samples were investigated at varying times compared to the onset of the disease. 82.5% of the patients presented with alimentary and 17.5% with biliary pancreatitis. The study of the histologic tissues was