Hepatic actinomycosis - A potential mimicker of malignancy

Actinomycosis is a rare granulomatous disease caused by commensal bacteria (Actinomycetaceae family) of the oropharynx, gastrointestinal, and urogenital tract. Infection most commonly involves the cervicofacial region but less frequently the abdominal region, typically secondary to a disruption of normal gastrointestinal mucosa. We present a patient with vague symptoms of fevers and myalgias and a recent diagnosis of rectal cancer. On CT, there were multiple centrally hypoattenuating hepatic lesions suspicious for metastasis vs abscesses, also confirmed by ultrasound. Initial image guided biopsy was non-diagnostic. Laparoscopic resection of one of the hepatic lesions showed pus consistent with an abscess. No organisms were identified by culture and a sample was sent to an outside laboratory for genomic polymerase chain reaction (PCR) analysis where Actinomyces DNA was isolated. This case report highlights a rare presentation of primary hepatic Actinomycosis and some of the challenges in diagnosing Actinomycosis due to its variable clinical and radiological manifestations and lack of diagnostic sensitivity by traditional microscopy and culture based techniques.