Hepatobiliary and Pancreatic: Hepatic actinomycosis

Abstract

A 72-year-old man was investigated because of a 1-week history of fever, headache and myalgia. Seven years previously, he had been diagnosed with gastric adenocarcinoma and treated with a subtotal gastrectomy. On admission to hospital, his temperature was elevated (38.3°C) but no other abnormalities were detected on physical examination. Laboratory tests revealed mild anemia (hemoglobin 114 g/l), an elevated white cell count (12.6x10/l) and a mild elevation of C-reactive protein (13.6 mg/l), aspartate aminotransferase (53 u/l), alanine aminotransferase (65 u/l), alkaline phosphatase (222 u/l) and g-glutamyl transferase (264 u/l). His serum glucose was also elevated. A contrast-enhanced computed tomography (CT) scan showed several lesions of low-attenuation in both lobes of the liver (Figure 1). The differential diagnosis included liver abscesses and liver metastases. A percutaneous aspirate was obtained under ultrasound guidance and yielded thick brown turbid fluid. In wet-fixed smears, blue colonies of actinomycosis with “bales of wool” appearance were seen on a background of mixed inflammatory cells (Figure 2). In cell-block sections, there were many irregularly lobulated or scalloped basophilic granules termed “sulphur granules” that are characteristic of Actinomyces. There was no evidence of metastatic adenocarcinoma. Gram staining revealed positive filamentous bacilli (Figure 2 inset, white arrow). The patient was treated with percutaneous drainage for 2 weeks and with high-dose penicillin-G given intravenously. His fever subsided after 2 weeks and laboratory tests gradually returned to normal. The abscesses had resolved on repeat CT scan after 2 months. Hepatic actinomycosis is a rare disease. Although cases of primary hepatic actinomycosis have been described, actinomycosis appears to spread to the liver from other abdominal sites in the majority of cases. Symptoms are often non-specific with weight loss and fever. However, most patients with hepatic actinomycosis have an elevated serum alkaline phosphatase level in addition to a leucocytosis and elevated erythrocyte sedimentation rate. The typical radiological feature is that of multiple liver abscesses but multiple small lesions may be difficult to characterize. Percutaneous aspirates can be diagnostic when they contain “sulphur granules” with gram-positive bacilli. Cultures are positive in some but not all patients. Larger abscesses can be treated by percutaneous drainage but eradication of the infection usually requires prolonged courses of intravenous penicillin. The evolution of hepatic abscesses caused by actinomycosis is usually more insidious than that associated with pyogenic abscesses.