Intraabdominal actinomycosis resulting in a difficult to diagnose intraperitoneal mass: A case report

Actinomycosis is a chronic suppurative granulomatous disease caused by Actinomyces israelii. Preoperative confirmed diagnosis is very difficult, so most cases are diagnosed preoperatively as malignant tumors. We report a case of intraabdominal actinomycosis which was difficult to diagnose preoperatively.

A woman, 60 years old, experienced discomfort in her lower right abdomen. She complained of nausea and anorexia and visited our hospital. Laboratory blood tests, abdominal CT, and abdominal MRI led to a diagnosis of a uterine sarcoma or primary intestinal mass, and she underwent surgery. Her histopathological diagnosis was intraabdominal actinomycosis.

Actinomycosis is a chronic purulent granulomatous inflammation caused by Actinomyces israelii. No clinical symptoms or laboratory findings are characteristic of abdominal actinomycosis, so this disorder is very difficult to diagnose preoperatively. Therefore, many cases are diagnosed as malignant tumors and undergo surgery. After surgery, long-term antibiotic treatment (penicillin) is usually administered.

We reported a case of intraabdominal actinomycosis that resulted in a difficult to diagnose intraperitoneal mass. When a large intraperitoneal mass is found, actinomycosis needs to be included as one of differential diagnoses.