Inflammatory pseudotumor of the liver with subphrenic abscess

A 62-year-old man who developed a high fever and right hypochondralgia was referred to our hospital. Based on his laboratory data on admission, (WBC count of 16200/μl and CRP of 11.8 mg/ml), the patient was presumed to have severe inflammation. A multiloculated hypoechoic lesion, 5 cm in diameter, was detected ultrasonographically in the posteroinferior segment of the liver accompanying fluid pooling was noted in the right subphrenic space. Abdominal CT scan and MR imaging studies demonstrated the same lesion characteristics as the ultrasonographic findings. We diagnosed a liver abscess, then performed percutaneous US guided drainage. One month later, the features of the lesion had changed to those of a homogeneous hypoattenuating mass on CT scan. Partial hepatectomy of the posterior segment was performed because malignant disease was suspected based on the needle biopsy specimen. The excised liver specimen revealed a solid mass which was pathologically diagnosed as an inflammatory pseudotumor. We speculate that the liver abscess had developed into an inflammatory pseudotumor during the course of treatment.