[Retroperitoneal fibrosis and multiple myeloma: fortuitous association?].

We report a 59-year-old man presenting with retroperitoneal fibrosis (RF) associated with IgG lambda multiple myeloma. Recent clinical and immunohistochemical findings suggest that RF might be a particular expression of plasma cell/lymphoid dyscrasia, and that this association is not merely fortuitous. We review the pathophysiological evidence supporting this hypothesis.