Abdominopelvic actinomycosis involving the gastrointestinal tract: CT features.

PURPOSE: To assess the computed tomographic (CT) features of abdominopelvic actinomycosis involving the gastrointestinal tract. MATERIALS AND METHODS: CT scans were analyzed in 18 patients with pathologically proved abdominopelvic actinomycosis involving the gastrointestinal tract. Eight patients had a history of using intrauterine contraceptive devices. Bowel site, wall thickness, length, bowel involvement patterns, inflammatory infiltration, and features of peritoneal or pelvic mass, if present, were evaluated at CT. RESULTS: Of the gastrointestinal tract, the sigmoid colon was most commonly involved (50%). All patients showed concentric (n = 15) or eccentric (n = 3) bowel wall thickening, with a mean thickness of 1.2 cm and a mean length of 8.3 cm. The thickened bowel enhanced homogeneously in nine patients and heterogeneously in the other nine. Inflammatory infiltration was mostly diffuse and severe. In 17 patients, a peritoneal or pelvic mass (mean maximum diameter, 3.2 cm) was seen adjacent to the involved bowel and appeared to be heterogeneously enhanced in most cases; infiltration into the abdominal wall was seen in four patients. CONCLUSION: Actinomycosis should be included in the differential diagnosis when CT scans show bowel wall thickening and regional pelvic or peritoneal mass with extensive infiltration, especially in patients with abdominal pain, fever, leukocytosis, or long-term use of intrauterine contraceptive devices.