Abdominal actinomycosis. Report of 4 cases

We report 4 cases of pathologically proven abdominal actinomycosis. US and CT demonstrated an infiltrative abdominal mass with ill-defined margins and heteregeneous enhancement after IV contrast. The ileo-cecal region was inv olved in one case; the mass appeared following cholecystectomy and recurred 3 years after surgical resection in one case; and no predisposing factor w as identified in the 2 other cases. In one of these, recurrence was observe d 12 years after the first epi sode. Actinomycosis must be included in the differentiel diagnosis of invasive abdominal lesions with "malignant" appea rance.