Hepatic Actinomycosis: A Rare Culprit in Liver Infections

Introduction: Actinomyces is a gram (+) aerobic bacteria found commonly in the mouth, GI tract and female urogenital tract. Although part of normal human flora, it can lead to infection in rare cases. It predominately affects the head/neck area, however intraabdominal infections are seen in 20% of cases with 15% of these involving the liver. Diagnosis is often challenging due to its slow growth and indolent course. Here we review a rare case of hepatic actinomycosis. Case Description/Methods: A 60-year-old man with a history of CAD and HTN presented to the ED with 2 months of increased urinary frequency, dizziness and 2 days of abdominal pain. He was tachycardic with otherwise normal vitals. Labs revealed elevated lactate, Cr, AST and WBC. Within 8 hours he rapidly deteriorated, developing septic shock and AHRF. He was intubated, started on vasopressors and admitted to MICU. CTAP revealed a heterogeneous hypodensity in the left hepatic lobe with concern for mass vs abscess. MRI later confirmed fluid collection consistent with an abscess. A drain was placed by IR, and no growth was seen in drainage cultures however cytology did reveal actinomyces. Patient had no clinical improvement despite prolonged course of broad spectrum antibiotics. On further review of imaging, a calcified linear foreign body with surrounding edema was noted (possibly a fish bone), along with trace extraluminal air in the duodenum indicating site of perforation. Patient was planned for hepatic resection once more stable, however he deteriorated further and passed away from multiorgan failure 5 weeks into hospitalization. Discussion: Hepatic actinomycosis accounts for 5% of all cases and is usually caused by mucosal injury from recent abdominal surgery, endoscopic manipulation, ulcers, foreign bodies or indwelling IUDs. Clinical manifestation is often nonspecific, with cystic abscess seen on imaging that is often misdiagnosed as a primary or metastatic liver cancer. Definitive diagnosis is made on histopathologic exam, and obtaining cultures is often challenging due to short incubation periods and inadequate growing conditions. Treatment includes antibiotics (IV penicillin followed by oral penicillin), drainage, and/or resection. Many cases show excellent outcomes with above treatments, although this was not the circumstance for our patient. This case highlights that although rare, hepatic actinomycosis should be considered in patients with vague constitutional symptoms and findings of hypodense liver lesions to initiate prompt treatment.Figure 1.: Heterogenous hypodensity in left lope of liver seen on CT and MRI.