3^rd Edition of Infectious Diseases World Conference 2026

Abstract

Actinomycosis is a rare, chronic purulent disease caused by Actinomyces spp, anaerobic gram-positive bacteria. Actinomycosis usually infects patients with a compromised mucosal barrier and in most cases occurs after surgery, trauma, neoplasia, dental procedures, aspiration of secretions, or infections such as appendicitis or diverticulitis. Abdominal actinomycosis accounts for approximately 20% of cases. The appendix, cecum, and colon are the most common abdominal sites of actinomycosis, which can occur weeks to years after disruption of the gastrointestinal mucosa. The limited number of symptoms makes diagnosis difficult, where less than 10% of actinomycosis infections are diagnosed preoperatively. Intra-abdominal actinomycosis can manifest as an abdominal mass of unclear benignity and may mimic a malignant tumor.

We present a clinical case of a 58-year-old patient who was admitted to the Military Medical Academy (MMA) with periodic complaints of abdominal swelling, heaviness, and increased gas formation. Abdominal ultrasound revealed a suspicious cocarde at the hepatic flexure, and fiberoptic colonoscopy was performed, which revealed a polypoid infiltrative process obstructing the lumen, with no proximal penetration possible. The histology of the biopsy showed a colon ulcer with actinomycosis. The conclusion from the abdominal CT scan was a high-density formation in the ascending colon, most likely related to the histologically verified pseudotumor actinomycosis. Prolonged courses of antibiotics with Amoxicillin/Clavulanic acid and Benzathine Benzylpenicillin were administered.

Two months later, due to the lack of response to antibiotic therapy, cessation of defecation and reduction of flatulence, and X-ray data for hydro-aerial shadows of the small intestine type with dilation in the middle abdominal floor, the patient underwent right hemicolectomy with ileotransverse anastomosis.

Intraoperatively, a tumor formation of the cecum with a diameter of about 15 cm was found. Histologically, moderately and poorly differentiated adenocarcinoma with abscess formation and xanthogranulomatous inflammation was verified.

The patient was discharged in stable general condition with a final diagnosis of  Cecum Ca - G2-3pT3N2aMxLv and referred for chemotherapy. In conclusion, abdominal actinomycosis should be included as a differential diagnosis when an unusual mass or abscess is found on abdominal computed tomography. Histological verification of actinomycosis in an established tumor process in a specific section of the colon cannot rule out the possibility of malignancy in an adjacent section.