Retroperitoneal fibrosis with perinuclear antineutrophil cytoplasmic antibodies and a longitudinally extended periaortic soft-tissue structure on CT

A 63-year-old woman showed positive perinuclear antineutrophil cytoplasmic antibodies (pANCA) and presented with an interesting CT finding of a periaortic soft-tissue structure seen as a rind of tissue surrounding the aorta, extending longitudinally from descending thoracic aorta to bilateral common iliac arteries which was compatible with an early stage of retroperitoneal fibrosis (RPF). Both pANCA titers and a periaortic mass volume were reduced following corticosteroid treatment. No cases of RPF with a periaortic mass associated with pANCA have been described. Our findings of RPF with pANCA positivity may enlarge the groups of ANCA-associated diseases.