Retroperitoneal fibrosis and p-ANCA-associated polyarteritis nodosa: coincidental or common etiology?

We describe a 65-year-old female patient who presented with idiopathic retroperitoneal fibrosis and polyarteritis nodosa. In addition, antineutrophil cytoplasmatic antibodies were found with specificity for myeloperoxidase (p-ANCA; anti-MPO). Following immunosuppressive treatment, regression of signs and symptoms was observed, together with the disappearance of these specific antimyeloperoxidase antibodies. These findings, combined with data available in the literature, suggest a common pathogenesis of both disorders, possibly involving antineutrophil cytoplasmatic antibodies.