Idiopathic retroperitoneal fibrosis: clinical features, treatment modalities, relapse rate in Greek patients and a review of the literature.

Objectives: Retroperitoneal fibrosis (RPF) is mostly idiopathic (iRPF); however, it can be secondary to drugs, malignancies, infections, or, as recently recognised, can be part of the IgG4-related diseases. The aim of our study was i) to describe the presenting clinical/laboratory/imaging features and treatment modalities used in patients with iRPF and ii) to evaluate factors potentially associated with disease relapse.

Methods: The medical records of patients diagnosed with iRPF and followed in four tertiary medical units in Athens, Greece from 2000 to 2018 were retrospectively evaluated.

Results: Sixty-seven patients with iRPF were included in the study. Seventy-three per cent were males, with a mean age at diagnosis 56.0±9.2 years. Low-back pain (63%) and constitutional symptoms (57%) were the commonest presenting symptoms. Elevated acute-phase reactants (78%), anaemia (43%) and impaired renal function (41%) were the most common laboratory findings. Serum IgG4 at diagnosis was evaluated in 36/67 patients and 36% of them had elevated levels (mean 297.7±166.3mg/dL). Diagnosis was mainly based on abdominal CT and/or MRI. Clinical/laboratory/radiological presentation did not differ between patients with elevated and normal serum IgG4 levels. Steroids were used as first-line treatment in 98%. Relapse occurred in 28.6% after a mean of 43.1±31.8 months. Relapse did not associate to initial clinical/imaging findings or to any treatment used, however patients with increased serum IgG4 had a significantly higher relapse rate (75% vs. 25%, p=0.005).

Conclusions: Relapse occurred in one-fifth of patients independently of the initial clinical/radiographic presentation or treatment used. iRPF patients with baseline elevated serum IgG4 levels have a higher relapse rate.