Retroperitoneal fibrosis associated with orbital pseudotumor without evidence of IgG4: A case report with review of literature.

Retroperitoneal fibrosis (RPF) is a rare disease characterized by chronic inflammation and periaortic fibrosis that affects retroperitoneal structures and often entraps the ureters. The idiopathic form has an incidence of 0.1-1.3/100,000 person-years. A substantial percentage of patients with idiopathic retroperitoneal fibrosis (IRF), as well as patients with orbital pseudotumor, is associated with IgG4-related disease (IgG4-RD). It is not clear what percentage of IRF is related to the spectrum of the IgG4-RD or if both represent different stages of the same disease (especially in those cases with extra-retroperitoneal involvement). Histopathological features such as storiform fibrosis, obliterative phlebitis and tissue infiltration of IgG4-positive plasma cells (ratio IgG4+/IgG higher than 0.4) are essential to identify this association. Extra-retroperitoneal manifestations are often presented among patients with IgG4-related RPF. About 90% of cases of IRF have a good prognosis, with adequate response to treatment. We report a case of a 59-year-old woman with history of past occupational asbestos exposure and smoking habit. She was diagnosed with RPF, periaortitis and orbital pseudotumor, without histopathologic or serologic features of IgG4- related disease. This could be related to the fact that the biopsy was done in a place with scarce inflammatory activity but high fibrosis. We want to emphasize the usual need to perform several biopsies or to be guided by positron emission tomography (PET-CT) in order to achieve a histopathological confirmation. Our case differs from the main IgG4 international cohorts in the involvement of the retroperitoneum, aorta and eye, whereas the usual involvement includes liver, pancreas, lymph nodes and salivary glands. Our patient had lower IgG4 serum levels than those described in the international cohorts. However, they were similar to those of the Spanish population.