Intimal angiosarcoma masquerading as retroperitoneal fibrosis

We present a rare case of intimal angiosarcoma arising from the iliac artery with unusual symptoms and signs mimicking retroperitoneal fibrosis (RPF). This 84-year-old male presented with constitutional symptoms, abdominal pain, increased acute-phase reactant levels, impaired renal function and a CT-documented left-sided parailiac soft-tissue mass with unilateral extrinsic ureteric obstruction. Whole-body ¹⁸F-fluorodeoxyglucose positron emission tomography scan showed highly increased FDG-uptake in a horseshoe-like pattern surrounding the left common iliac artery, but no pathologic activity elsewhere. Further diagnostic workup revealed no signs of malignancy. Because of its location, CT-guided biopsy of the mass was precluded. A tentative diagnosis of RPF was made and treatment with Tamoxifen 20 b.i.d. was started. However, his condition gradually deteriorated, eventually succumbing to severe pneumosepsis. Autopsy revealed extensive iliac intimal angiosarcoma with infiltrative expansion to the left ureter and tumor emboli in both lungs. The present case suggests that intimal angiosarcoma should be included in the differential diagnosis of suspected RPF.