Actinomycosis mimicking pancreatic neuroendocrine tumor. Case report and review of the literature

Background Abdominal actinomycosis is an uncommon subacute or chronic inflammatory disease due to a filamentous, gram-positive, anaerobic bacterium: Actinomyces israelii. The pathogen invades surrounding tissues, spreads by contiguity causing a suppurative and granulomatous inflammation with formation of abscess. Methods Case report: A 66-year-old asymptomatic woman with incidentally radiological finding of a pancreatic head solid mass. Approximately 35 years before, she underwent cholecystectomy and choledocotomy for gallstones of the biliary tract. Suspecting of a neuroendocrine tumor, the patient was enrolled to pancreaticoduodenectomy. Results Histologic examination revealed pancreatic actinomycosis. Foci of severe dysplasia of the pancreatic ductal epithelium were found, and bacteria referable to Actinomyces were isolated. Conclusions Pancreatic actinomycosis is extremely rare but it should be considered in the differential diagnosis with other pancreatic disease. In the literature, it was been reported that the abdominal location could be related to contamination by gallstone spillage during biliary surgery. Prognosis is excellent if actinomycosis is well treated; early diagnosis is mandatory but remains a challenge, and often is achieved only after surgery.