Abstract
In 1982, we reported a case of retroperitoneal fibrosis (RPF) exhibiting various clinical manifestations. Our current understanding of immunoglobulin G4 (IgG4)-related disease led us to consider it as a possible diagnosis because all of the patient's clinical features could be explained by this disease entity. To confirm our hypothesis, were investigated the histopathological findings of resected specimens that had been stored for 35 years postoperatively. Typical pathological findings together with predominant IgG4(+) plasma cell infiltration confirmed a potential diagnosis of IgG4-related RPF. Furthermore, we observed positive immunohistochemical staining for several molecules associated with T regulatory and T follicular helper cells.