Abstract
A 12-year-old boy was admitted for right lower abdominal pain was found in ultrasonography (US) and computed tomography (CT) to have a mass at the site of tenderness, and laboratory examinations revealed leukocytosis and positive CRP. The mass lesion was suspected of being an abscess near the cecum or terminal ileum, but the tumor was not completely denied. On laparotomy, the swollen appendix and major omentum adhering to it were resected and he was discharged. On postoperative day (POD) 8, he was readmitted for a high fever. Abdominal CT showed an abscess, and a colony of actinomyces was found in the granuloma of the major omentum after a pathological examination. We started conservative therapy for actinomycosis. By day 20 from readmission, the fever had subsided, the abdominal mass had disappeared, and he discharged. Actinomycosis is now rare, but it should be kept in mind when we encounter an abdominal mass with signs of inflammation.
