A rare case of abdominal actinomycosis mimicking ovarian cancer with presumed hepatic involvement and abdominal wall involvement.

Abdominal actinomycosis is a chronic infection caused by anaerobic Gram-positive Actinomyces species. Because of its infiltrative growth, abscess formation, and fibrotic reaction, it may closely mimic malignant disease. We report the case of a 53-year-old woman presenting with abdominal pain and a palpable epigastric mass. Imaging showed a pelvic mass with abdominal wall involvement and a hepatic lesion, initially suggestive of advanced pelvic malignancy. Tumor markers were within normal limits. Because of persistent diagnostic uncertainty, the patient underwent elective exploratory laparoscopy with biopsy. Intraoperative findings showed a firm pelvic mass involving the right adnexa and uterus, without a clear tissue plane. Frozen-section examination initially suggested a small-cell neoplasm, whereas definitive histological examination confirmed abdominal actinomycosis. The hepatic lesion was not biopsied; therefore, hepatic involvement was considered presumptive, based on the radiological findings and complete regression after prolonged antibiotic therapy. Long-term intrauterine device use represented a relevant predisposing factor. Abdominal actinomycosis should be considered in the differential diagnosis of infiltrative pelvic masses. A conservative diagnostic surgical approach combined with prolonged antibiotic therapy may avoid unnecessary radical surgery.