Serum IgG4 Concentration is a Potential Predictive Biomarker in Glucocorticoid Treatment for Idiopathic Retroperitoneal Fibrosis

Objectives: To evaluate the management and outcome of idiopathic retroperitoneal fibrosis (iRPF) in Japan, and identify its clinical biomarker. Methods: We retrospectively analyzed 129 patients with iRPF treated between January 2008 and May 2018 at 12 university and related hospitals. Patients treated with glucocorticoid were analyzed to identify a predictive biomarker. These patients were classified into three groups according to overall effectiveness (no change: NC, complete response: CR and partial response groups: PR), and each parameter was compared statistically.Results: Male-female ratio was 5: 1, and median age at diagnosis was 69 (33-86) years. Smoking history was reported in 59.6% of the patients. As treatment, 95 patients received glucocorticoid therapy with an overall response rate of 84%. As a result, serum concentration of IgG4 was significantly decreased in NC group compared with the other two groups (56.6mg/dL vs 255mg/dL, 206mg/dL, P=0.0059 and 0.0078). ROC analysis was performed between the non-responder (NC) and responder groups (CR+PR) to identify the cut-off value of serum IgG4 as a predictive marker. As a result, AUC was 0.793 and the values of sensitivity and specificity were 0.85 and 0.64, respectively, under the cut-off values of 67.6mg/dL. Conclusions: In the majority of iRPF patients, glucocorticoid therapy resulted in a favorable response. Pre-treatment serum IgG4 concentration may have potential as a predictive biomarker of steroid treatment.

Surviving Complications of Retroperitoneal Fibrosis with Intermittent Relapses over a Period of 20 years: Case report and literature Review

Idiopathic retroperitoneal fibrosis is a rare fibro-inflammatory disease of varied etiology which usually originates around aorta and spreads caudally along Iliac vessels into adjacent retroperitoneum causing ureteral obstruction as the most frequent complication. A 53-year-old male patient presented with complaint of mild pain in both the legs off and on. On investigating further, we found that he had been struggling with intermittent relapses every 3-4 years for last 20 years since he was first diagnosed with Idiopathic Retroperitoneal Fibrosis. He was 33-year-old when he first developed the symptoms of anuria for 48 hours and was diagnosed with Idiopathic retroperitoneal fibrosis. This was followed by atrophy of left kidney and hypertension 6 years later, then hypothyroidism after another 3years and finally involvement of Inferior Vena Cava and acute Deep Vein Thrombosis of lower limbs after another 3-4 years. His deep vein thrombosis was well managed in time. He was put on glucocorticoids everytime he had a relapse and a complication. We did a review of literature to understand recent advances about its pathogenesis, diagnosis, investigations and management. We searched in PubMed using terms like retroperitoneal fibrosis alone and in combination with related terms such as Inferior Vena Cava thrombosis, Deep Vein Thrombosis, Tamoxifen, Methotrexate. This case is unique as it is very rare to find acute Deep Vein Thrombosis in Idiopathic retroperitoneal fibrosis without development of any collaterals when Inferior Vena Cava lumen is compromised to almost complete obstruction. After a follow up of 20 years patient is doing well in terms of physical activity and psychological wellbeing with anti-hypertensives, thyroxine and anti-coagulants. Is the disease-free interval actually free of the disease or it just subsided with immunosuppressants to become active after some time?