Rituximab for idiopathic and IgG4-related retroperitoneal fibrosis

Retroperitoneal fibrosis (RPF) refers to a fibro-inflammatory lesion in the retroperitoneum, often anterolateral to the aorta. Most cases are due to IgG4-related disease (IgG4-RD) or are idiopathic. RPF can lead to severe morbidity. Treatment strategies remain poorly-defined. We evaluated the efficacy and safety of rituximab (RTX) for idiopathic or IgG4-related RPF. We retrospectively reviewed the records of patients who had RPF treated with RTX. Treatment response was determined by assessing changes in both clinical features, including symptoms and laboratory measurements, as well as in the radiographic dimensions of the lesion. Twenty-six patients with IgG4-related (n = 19) or idiopathic RPF (n = 7) were identified. Patients without histopathological evidence of IgG4-RD on either retroperitoneal biopsies or sampling of extra-retroperitoneal organs were considered to have idiopathic RPF. Of the 26 patients, 19 (73%) received RTX without additional glucocorticoids. All 19 patients who presented with pain reported symptomatic improvement following RTX. Among 25 patients with follow-up imaging, 22 (88%) had radiologic improvement. Among 10 patients with ureteral stents and/or percutaneous nephrostomy tubes, 4 (40%) underwent successful stent or tube removal. Responses to treatment were similar among those treated with RTX monotherapy and those treated with RTX and glucocorticoids. RTX was generally well tolerated, but 3 (12%) patients experienced severe infections. In this study, RTX for RPF led to resolution of symptoms in all patients and radiographic improvement in the majority. Prospective studies of RTX for RPF are indicated.