Management of patients with huge pelvic actinomycosis complicated with hydronephrosis: a case report.

Actinomycosis is an uncommon, chronic, granulomatous disease caused by several species of the genus Actinomyces, a Gram-positive, filamentous bacterium that normally colonizes mucosal areas. Actinomycosis can be mistaken for malignant tumors, and in most cases the diagnosis is delayed or missed entirely until surgery. Actinomycosis in the abdomen or pelvis mostly results from prolonged use of an intrauterine device. We report the case of a 40-year-old female who presented with decreased urine production, poor appetite, marked loss of body weight and intermittent lower abdominal pain for 3 months. Abdominal computed tomography indicated a large infiltrative pelvic mass that was complicated by bilateral hydronephrosis, bladder compression and small bowel adhesions. Despite the elevated levels of cancer antigen 125, we suspected pelvic actinomycosis because of a 15-year history of an intrauterine device. The diagnosis was confirmed by histopathological examination of soft tissue obtained from a laparotomy biopsy. We successfully treated the patient with prolonged antibiotics instead of surgical eradication. Abdominal computed tomography obtained 1 year later showed almost complete resolution of the pelvic inflammatory mass.