RÉSUMÉ
Actinomycosis is a chronic, slowly progressive, and suppurative disease caused by filamentous anaerobic bacteria Actinomyces, which results in characteristic sulfur granules. Clinically, actinomycosis can present with a mass-like lesion, and this bacterial nidus has been frequently mistaken for a malignancy. For that reason many patients undergo surgical resection before the correct diagnosis is established. We report a case of a 63-year-old man with a solitary, asymptomatic pancreatic actinomycosis that masqueraded as pancreatic cancer. He did not have any other concurrently infected organs and did not have any signs or symptoms of infection. All radiologic images of the patient favored a malignancy to a great extent rather than an inflammatory mass. He was finally diagnosed with actinomycosis by endoscopic ultrasound (EUS)-guided fine needle aspiration biopsy without surgery. After one month of treatment with antibiotics, the pancreatic head mass was completely resolved on the follow-up computed tomography (CT).