Pancreatic ductal adenocarcinoma mimicking primary retroperitoneal fibrosis. Case report:

Introduction: One of the defining feature of pancreatic ductal adenocarcinoma (PDA) is the presence of extensive desmoplasia. The volume of stroma production can be disproportionate relative to mass of the tumor. Primary retroperitoneal fibrosis (PRF) is characterized by progressive accumulation and spread of connective tissue in the retroperitoneal space often leading to entrapment of ureters and/or the distal part of the duodenum. The large amount of stroma can mimic the radiologic features of PRF. We present a case when the diagnosis of pancreatic ductal adenocarcinoma was delayed because of the tumor showed retroperitoneal spread and imaging studies were distinctive for PRF. Case report. The past medical history of the 77 year old patient was significant for chronic renal failure of postrenal origin diagnosed one year before. The abdominal CT-scan performed six month ago was unremarkable except for focal stricture and upstream dilation of both ureters. After a relatively uneventful course during the past six months, the patient presented with abdominal distension and vomiting of five days period. Abdominal CT- scan revealed an extensive infiltration of the retroperitoneal space by a tissue with radiologic features characteristic for PRF. The fibrotic tissue involved the prerenal fascia, both ureters, and the third part of the duodenum. Duodenoscopy disclosed complete duodneal obstruction caused by an external compression at the level of ligament of Treitz. At surgery, a a hard, fibrous tissue extending form the hepatic hilum down to the pelvis have been seen. The infiltrating tissue also entrapped the distal duodenum leading to its obstruction. Histologic evaluation of specimens taken at surgery showed features of fibroplastic PDA. Conclusion: PDA may present as a extensive retroperitoneal fibrosing process without detectable intrapancreatic tumor on radiologic studies. Obsructive signs of any retroperitoneal organ (ie. ureters, duodenum) should raise the possibilty of retroperitoneally expanding PDA.