A serial histologic study of the healing process after relapsing edematous acute pancreatitis in the rat.

This study was undertaken to investigate the serial histologic factors of the healing process in the rat after relapsing edematous acute pancreatitis induced by the closed duodenal loop. Serum amylase levels in single, second and third attacks of edematous acute pancreatitis were elevated significantly compared with those in the control group (p less than 0.01), but the concentrations were similar in the three groups and it returned to normal by the seventh day after the attack. However, the histologic finding was different. The histologic factors of the pancreas on the first day after the first attack showed interstitial edema and a mild inflammatory cell infiltration which returned to normal on the seventh day. Histologic findings on the first day of the second attack showed the same histologic changes with mild degenerative changes and partial degenerative atrophy of the acinar cells. On the seventh day after the attack, partial degenerative atrophy of the acinar cells, proliferation of the small duct and slight interstitial fibrosis remained but returned to normal one month later. On the first day after the third attack, histologic findings showed more obvious changes compared with the first and second attacks. There was much diffuse interstitial edema, a heavy inflammatory cell infiltration and massive necrosis of the acinar cells. One month later, a diffuse marked fibrosis in the interstitial space and intralobular tissue associated with small duct proliferation remained. The results indicate that repeated attacks of edematous acute pancreatitis may lead to more chronic pancreatic damage.