Disseminated Intra-abdominal Actinomycosis Mimicking Colorectal Carcinoma With Diffuse Intra-abdominal Carcinomatosis: A Case Report.

Actinomycosis is a rare opportunistic bacterial infection. It most commonly affects the cervicofacial area and is less common in the gastrointestinal area. Because of the ambiguous clinical pictures, there is a low preoperative diagnosis rate and a high rate of misdiagnoses. In this case report, we have an unusual presentation of disseminated abdominal actinomycosis in a diabetic male patient with no previous history of surgery or trauma. He presented with abdominal pain for two years. Abdominal imaging showed rectal wall thickening with adhesion and attachment to the bladder, and small bowel with omental and peritoneal deposits, mimicking colorectal cancer with abdominal carcinomatosis. Histopathological examination, however, revealed actinomyces infection with no evidence of malignancy. In such cases, the recovery rate with antibiotic therapy is very high in conjunction with surgical resection.