Actinomycosis of Sigmoid Colon: Mimicking a Colon Cancer

Abdominal actinomycosis is a rare infectious disease caused by an anaerobic bacterium actinomyces israeli. Pelvic actinomycosis is generally associated with the use of intrauterin devices (IUD). This chronic suppurative infection can mimic pelvic malignancy. The diagnosis of the disease is frequently miss preoperatively. The surgeons must be aware of this rare complication in order to avoid an extensive surgical procedure. Case: We present the case of a 31 year old premenoposal woman with an abdominal pain and a history of IUD us efor 6 years. On physical examination the patient had tenderness on right lower abdomen and a palpable cystic mass 8x10 cm in size on pelvic bimanual examination. A preoperative transvaginal USG showed a 9x9 cm cystic mass originated from right ovary. The patient was taken to the emergency operating suite with the diagnosis of torsion of the right cystic ovary by gynaecologist. During the exploratory laparotomy we observed an extensive diffusely infiltrating process involving right adnexa, sigmoid colon sacrum and right pelvic Wall. A loop of jejunum was adherent to this infiltrating process and a mass 5x6 cm in size was palpated in sigmoid colon. These findings were highly suggestive of a colonic carcinoma and the patient was consulted with a general surgeon intraoperatively. Right salpingo -ooferectomy + sigmoid resection + segmental jejunal resection was performed. Pathologic findings showed chronic inflammatory tissue with evidence of actinomycosis. Conclusion: The case described here underlines that surgeons must be aware of this unusual infectious disease in the differential diagnosis of pelvic mass.