[1399] Paraduodenal Pancreatitis Is One of the Main Causes of Pseudotumor in the Pancreas and Periampullary Region: Features of a Distinct Entity Becoming Clearer

I Coban, O Basturk, D Martin, B Kalb, J Sarmiento, D Kooby, C Staley, NV Adsay. Emory Uni., Atlanta; NYU, NY

Background: Paraduodenal pancreatitis (PDP) was recently proposed as a unifying term for a distinctive subset of pancreatitis previously reported under cystic dystrophy of heterotopic pancreas, groove pancreatitis and those associated with paraduodenal wall cyst. There has not been any systematic study of this entity.
Design: Clinicopathologic findings of 31 PDP cases among 700 pancreatic head resections were reviewed.
Results: Overall incidence: 4%. All, clinically misdiagnosed as carcinoma. Increasingly common cause of pseudotumor (among the last 100 resections, 7 PDP vs 2 LPSP). M/F= 21/10. Mean age, 50. H/O smoking and alcohol in 19/21. MRI (evaluated retrospectively in 12): Distinctive inflammation and abnormal enhancement of duodenal wall and a unique tubulocystic pattern along the expected course of accessory duct/minor papilla. Macroscopy: Mucosal-covered nodularities in the accessory ampullary region; narrowed lumen; on cut sections, thickened mucosa, trabeculation of the wall; homogenous firm-white pseudotumor extending to and in some, extensively replacing the pancreas especially in the groove region (groove pancreatitis), and variably sized cysts, some up to several cms (paraduodenal wall cyst). Microscopy: Brunner gland hyperplasia in the mucosa; on the wall, exuberant myoid proliferation intermixed with scattered round pancreatic lobules (myoadenomatosis), variably cystic ducts, some with partial duct-epithelial lining (cystic dystrophy of heterotopic pancreas) as well as ruptured ducts associated with hypercellular reactive tissue and stromal deposition of acinar secretions associated with inflammatory/fibroblastic reaction rich in eosinophils, foreign-body giant cells and eosinophilic abcesses.Stones in 17.
Conclusions: PDP is often mistaken as carcinoma clinically, and with advancing technology that allows recognition of less problematic mimickers, it constitutes an increasingly high percentage of pseudotumors. It is seen in the middle-aged with H/O of alcohol and smoking. Collaboration of macroscopic and MRI findings confirm that the process is centered in the accessory duct /minor papilla. It appears that PDP results from an alcoholic/obstructive injury inflicted upon a functioning but vulnerable accessory duct. Recognition of the distinctive features of this entity should allow accurate diagnosis both pre- and post-operatively.
Category: Liver & Pancreas

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 225, Wednesday Morning