Peritoneal pseudotumoral actinomycosis: A case report

Abdominal actinomycosis is an uncommon abdominal disease caused by Actinomyces species. It may appear as an abdominal mass and it has a tendency to infiltrate adjacent tissues this is why it is often mistaken for a malignant tumor. We report a case of a man who consulted our institution for abdominal pain and a palpable right upper quadrant mass. Computerized tomography (CT) scan showed intra-peritoneal tissue mass with irregular contours that invades the left colon and infiltrates the abdominal oblique muscles. The biopsy under colonoscopy could not eliminate a malignant tumor. A scanner-guided biopsy confirmed the diagnosis of actinomycosis. The sample revealed the presence of voluminous clumps of rounded basophilic germs, filamentous in appearance. High dose IV penicillin therapy was given with complete resolution of symptoms and a complete disappearance of the colonic wall thickening as well as the invasion of the abdominal wall in the CT.