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[Clinical characteristics of IgG4 related retroperitoneal fibrosis: a report of 5 cases and literature review].

OBJECTIVE
To explore the clinical characteristics, treatment and prognosis of IgG4-related retroperitoneal fibrosis (RPF).


METHODS
All the patients diagnosed as RPF in Peking University People's Hospital between February 2008 and October 2014 were included. Among them, 5 patients were identified as IgG4 related RPF. We analyzed their medical records and summarized the clinical, laboratory, and imaging features of IgG4 related RPF, which had taken the recent literature into account.


RESULTS
All the 5 patients were male, with the average age 62.2 years (55-67 years). They mainly complained of abdominal pain, flank pain and weight loss, two of whom had concurrent antoimmune pancreatitis. Renal insufficiency was present in 3 patients (3/5). Four patients (4/4) showed increased erythrocyte sedimentation rate (ESR), while 3 patients (3/4) had higher serum C-reactive protein (CRP) and IgG. In addition, 4 patients (4/4) had significantly elevated serum IgG4 level. On computed tomography (CT) imaging, 5 patients showed retroperitoneal mass which surrounded the abdominal aorta and the iliac arteries, and even enveloped the ureters and the inferior vena cava. Only one patient received tissue pathological examination, which indicated the numbers of IgG4-positive plasma cells per high power field>10 and a ratio of IgG4-positive cells to all IgG-bearing cells>40%. One patient received simple surgical intervention, and 1 patient received medical treatment alone, while the remaining 3 patients received combined treatment of surgery and medications. follow-up was available for the 4 patients, all of whom had good prognosis.


CONCLUSION
Part of RPF was actually IgG4-related, which was also nominated as IgG4 related RPF. It was a rare disease with unknown etiology, characterized by the elevated serum IgG4 concentration (≥1.35 g/L), with marked tissue infiltration by lymphocytes and IgG4-positive plasma cells with fibrosis, in addition to the presence of retroperitoneal mass. Glucocorticoids were the first-line therapy and IgG4 related RPF had a favourable prognosis.