18F-fluorodeoxyglucose positron emission tomography in a case of retroperitoneal fibrosis.

A patient with recurrent abdominal pain was admitted to our hospital. Computed tomography showed a soft dense mass surrounding the abdominal aorta at the infrarenal level, which was compatible with retroperitoneal fibrosis. (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography showed abnormal uptake of (18)F-FDG into these lesions. Two months after the initiation of corticosteroid therapy, the abnormal uptake of (18)F-FDG had ceased along with a reduction in the fibrous mass surrounding the abdominal aorta.