ABSTRACT
Splenic abscess is a rare disease that generally occurs in immunocompromised patients. It is difficult to distinguish between splenic abscesses and cysts using imaging studies, especially if they are asymptomatic. A 50-year-old asymptomatic man who had received steroid therapy for underlying rheumatoid arthritis was referred to a university hospital due to presence of several splenic cysts, with the largest being 3.5 cm in diameter. Percutaneous aspiration was performed, and fluid analysis showed cysts infected by extended-spectrum, beta-lactamase-producing Escherichia coli. The patient was treated with ertapenem for four weeks, and the lesion disappeared on follow-up imaging studies. Splenic abscess should be included as a differential diagnosis of splenic cystic lesions in immunocompromised patients.