Abdominal actinomycosis mimicking a transverse colon malignancy: a case report and review of the literature.

BACKGROUND Actinomycosis is a rare inflammatory bacterial disease caused by Actinomyces species which can infrequently affect the large intestine. Disseminated actinomycosis is reported as a rare complication associated with intrauterine devices. We report a case of intra-abdominal actinomycosis mimicking a transverse colon malignancy. CASE PRESENTATION A previously healthy 40-year-old Sinhalese woman was evaluated for intermittent colicky left-sided abdominal pain for 2 months' duration. Computed tomography of the abdomen showed a circumferential thickening of the wall and narrowing of the lumen of the descending colon with evidence of extraluminal extension to the adjacent parietal peritoneum and abdominal wall suggestive of a stage IV neoplasm. An exploratory laparotomy with extended left hemicolectomy was performed. Macroscopic evaluation revealed a mass lesion with multiple abscesses attached to the transverse and descending colon. Histology was suggestive of actinomycosis with no evidence of malignancy. CONCLUSIONS Abdominal actinomycosis should be considered in a young patient with chronic abdominal pain. It should be understood that the presentation may be vague and highly variable. Computed tomography-guided biopsy/fine needle aspiration or laparoscopy and biopsy may be useful in arriving at a diagnosis and can prevent unnecessary surgical intervention.