The best answer is choice A. Aspiration of an echinococcal cyst carries a risk of anaphylaxis and spread of infection and should only be done if there is serologic and radiographic uncertainty. Imaging typically shows a well-defined cyst with calcifications and budding daughter cysts.
- Risk factors and mechanism of action will suggest the most likely organisms and guide antibiotic choice.
- Entamoeba histolytica is the most common cause of liver abscess worldwide.
- Stool PCR and antibody testing for E. histolytica should both be ordered in the work-up of a liver abscess.
- Calcifications and daughter cysts budding off the main cyst can distinguish echinococcal cyst from E. histolytica abscess radiographically.