Hepatic microabscesses caused by Escherichia coli--US and CT appearance

Hepatic microabscesses have been described in immunosuppressed patients. However, there has been no previous report concerning hepatic microabscesses caused by Escherichia coli (E. coli). Recently, we experienced a 75-year-old male patient who had suffered from fever and upper abdominal pain for 4 days. His laboratory tests revealed an increased erythrocyte sedimentation rate (55 mm/hr), the white cell count was 7500/cumm with 82% segmented leukocytes, minimally elevated serum alkaline phosphatase and serum glutamic-pyruvic transaminase. Ultrasonography (US) showed multiple tiny hypo- or nearly anechoic lesions (3-8mm) diffusely scattered in both hepatic lobes. Some lesions were too small to be demonstrated and only distal acoustic enhancement posterior to the lesions could be noted. Contrast-enhanced computed tomography (CT) scan subsequently demonstrated the tiny hypodense and cystic lesions and confirmed the US diagnosis of microabscesses. Cultures of blood and liver aspirates showed E. coli. Although US and CT appearance of hepatic microabscesses caused by E. coli may be characteristic, it is not specific. Differential diagnosis should include multiple biliary hamartomas, and definite diagnosis should be made by needle aspiration.