Pancreatic Actinomycosis Presenting as a Pancreatic Head Mass

Context Actinomycosis is a chronic infection caused by an anaerobic non-acid fast organism, resulting in granulomatous inflammation and fibrosis. Pancreatic Actinomycosis is a rare condition which can mimic a pancreatic neoplasm. Case report We present a case of pancreatic Actinomycosis presenting as a pancreatic mass suspicious for malignancy. The initial computed tomography scan showed a capsulated, inhomogeneous lesion in the head of the pancreas with no biliary or pancreatic duct dilation. On multiphasic computed tomography scan, the lesion was suspicious for malignancy with a hypodense non-enhanced pattern, with no fat plane between the mass and superior mesenteric vein, and no plane between the mass and the medial aspect of the second portion of duodenum. After two biopsies and further review of pathology slides, gram-positive rod-shaped bacteria with formed fungus-like hyphae compatible with Actinomycosis were found. The pancreatic mass shrank and decreased significantly in size with penicillin therapy. Conclusion Actinomycosis should be considered in the differential diagnosis of a pancreatic mass of unclear etiology. Clinical suspicion should be discussed with pathologists for further evaluation of biopsy samples. Treatment with penicillin can be very effective for these lesions.