A Case of Asymptomatic Cecal Actinomycosis Found on Screening Colonoscopy

Abstract

Purpose: A 61 year old woman was referred for a screening colonoscopy in 2/11. She is average risk for colon cancer and has never had a colonoscopy before. She denied any gastrointestinal complaints. Her past medical and surgical history is significant for coronary artery disease and history of appendectomy via laparotomy for acute appendicitis in 10/08. Colonoscopy revealed a protruding stick like lesion in the cecal pole close to appendix. The protruding portion is covered with green to yellow colored debris with an ulcer at the base. Biopsies of the base of the lesion showed ulcerated colonic mucosa with acute inflammation along with the identification of Actinomyces species. A CT scan of the abdomen and pelvis with oral and IV contrast was obtained which was essentially normal without inflammation, fistulization, or evidence of abscess. Antibiotic therapy was started with oral Amoxicillin 500 mg TID with plan to continue for 6 months. However this was discontinued after 4 months of therapy as patient was unable to tolerate it due to side effects. A repeat colonoscopy was then performed and this revealed resolution of the cecal ulcerated lesion. The Actinomyces species is a gram positive, anaerobic bacteria usually found in the gastrointestinal and female genital tracts. The infection starts when a loss of integrity of the mucous membrane facilitates the entrance of the bacteria into the surrounding tissue. Initially the infection is asymptomatic while the abscess is small. As the abscess grows into the peritoneum and fistulizes, the patient develops symptoms. Complicated abdominal Actinomycosis symptoms include weight loss, nausea, vomiting, abdominal pain, fever, and a palpable abdominal mass. The onset is usually insidious but can occasionally be acute in the case of acute appendicitis. Abdominal Actinomycosis is known to be associated with abdominal surgery and abdominal trauma as well as to mimic acute appendicitis. Our patient underwent an appendectomy due to acute appendicitis prior to the diagnosis of cecal actinomycosis. Review of the records at the time of presentation of her acute appendicitis 3 years ago revealed a CT of the abdomen and pelvis that showed a dilated appendix (1.1 cm) with surrounding inflammation extending to base and cecum. The operative report noted the base of the appendix was thickened. Surgical pathology report revealed acute appendicitis with marked periappendicitis and an appendiceal diverticulum. She had an uneventful post operative recovery. It is possible that the cecal actinomyces in our patient was a result of post appendectomy infection or she had an actinomyces infection of the appendix, with spilling of bacteria into the cecum during surgery.