Abdominal actinomycosis mimicking malignancy: A case report

Actinomycosis is the infection caused by Actinomyces bacilli; subtypes include cervicofacial, pulmonary, and abdominal/pelvic actinomycosis. Abdominal actinomycosis can mimic intra-abdominal malignancies by causing manifestations like chronic lower abdominal pain, weight loss, and palpable mass(es). Treatment usually requires three to six months of high-dose penicillin G or amoxicillin. This report discusses an 88-year-old female who presented with chronic abdominal pain, weight loss, and other nonspecific symptoms without palpable abdominal mass. However, computed tomography (C.T.) imaging revealed multiple intra-abdominal soft tissue masses in the greater omentum, anterior abdominal wall, and small bowel mesentery. On biopsy, filamentous bacilli suspicious of Actinomyces was identified. The patient received prolonged antimicrobial treatment, underwent multiple CT-guided aspirations of recurrent abscesses, and had surgical intervention for sigmoid stricture. On subsequent imaging, the patient showed significant amelioration of omental and anterior abdominal wall masses. This case highlights the importance of prompt recognition and subsequent management of Actinomyces as an etiology of malignancy-like symptoms.