eP246 - Abdominal Actinomycosis Masquerading as an Invasive Malignancy

Purpose/Background: Abdominal actinomycosis, a rare and often misdiagnosed infection caused by Actinomyces species, poses diagnostic challenges due to its diverse clinical presentations. We present the case of a 54-year-old woman with comorbidities who initially exhibited right lower quadrant symptoms. Imaging indicated potential appendicitis or malignancy, leading to surgical exploration, revealing a cecal cuff tumor with acute and chronic appendicitis and actinomycete infection. This case underscores the importance of considering actinomycosis in the differential diagnosis of lower abdominal pain.Methods/Interventions: We conducted an extensive literature search to identify relevant articles, case reports, and clinical studies related to abdominal actinomycosis. Databases like PubMed, Embase, and Cochrane Library were queried using keywords such as "abdominal actinomycosis," "appendiceal actinomycosis," and "actinomycosis." Inclusion criteria covered studies published in the past two decades providing insights into pathogenesis, management, or outcomes of abdominal actinomycosis.Results/Outcomes: Abdominal actinomycosis often mimics acute appendicitis, malignancy, or inflammatory bowel disease, complicating diagnosis. Definitive diagnosis frequently requires histopathological analysis due to the inflammatory process's resemblance to malignancy. Diagnosis may necessitate a surgical specimen, limiting the ability to treat the underlying cause effectively. Actinomycosis typically requires long-term antibiotic therapy, differing from common gastrointestinal infections. While uncomplicated cases may respond to antibiotics, surgery becomes necessary when the diagnosis is uncertain, malignancy cannot be ruled out, or severe infection is unresponsive to medical treatment.Conclusion/

Discussion: Abdominal actinomycosis typically exhibits slow, localized progression, with symptoms emerging over several months. Opportunistic infection depends on underlying local conditions, such as trauma, surgeries, immunosuppression, foreign body presence, or a history of perforated viscera. In our case, the presence of a fecalith suggests a prior undiagnosed acute perforated appendicitis, enabling actinomycosis to spread to adjacent structures. This review highlights the diagnostic challenges of abdominal actinomycosis and emphasizes the need for further research to enhance accurate diagnosis and management, ultimately improving patient outcomes."Initial axial view CT

Right lower quadrant inflammatory mass infiltrating the abdominal wall.
Initial coronal view CT

Right lower quadrant inflammatory mass infiltrating the abdominal wall.
Initial sagittal-view CT

Right lower quadrant inflammatory mass infiltrating the abdominal wall.
Cecal cuff tumor

Cecal cuff tumor consisting of actinomycete colonies "