Background

Retroperitoneal fibrosis (RPF) is a rare immune-mediated disease characterized by abnormal fibrosis and inflammation in the retroperitoneal space, which is located deep within the abdomen. This process compresses major vessels and organs such as the ureters, aorta, and inferior vena cava. Initially, the disease presents with vague symptoms such as lower back pain or weight loss, making early diagnosis difficult. Consequently, diagnosis often occurs after significant ureteral compression and renal dysfunction. RPF is classified into idiopathic RPF (iRPF), with unclear causes, and secondary RPF, caused by factors such as cancer, infection, or drug administration. Current medical practice faces challenges in rapidly differentiating between these two types due to the diverse clinical presentations and complex differential diagnoses. Furthermore, the interplay of genetic predisposition and environmental factors in each patient limits the ability to accurately identify and address the underlying pathological mechanisms.

Key Findings

The recent seminar paper published in The Lancet provides a comprehensive overview of the latest pathological mechanisms, differential diagnosis guidelines, and optimized drug treatment strategies for RPF. Notably, a significant proportion of idiopathic cases are closely associated with IgG4-related disease (IgG4-RD), a systemic fibro-inflammatory disease. IgG4-RD-related RPF is characterized by excessive infiltration of lymphoplasmacytic cells and storiform fibrosis, leading to obliterative venitis, with significantly elevated serum IgG4 levels. In contrast, classical idiopathic RPF is characterized by a more localized immune response confined to the retroperitoneal region, resulting in a relatively milder degree of organ involvement. In terms of diagnosis, the study highlights the clinical value of positron emission tomography-computed tomography (PET-CT) and establishes criteria for accurately assessing the extent and activity of the disease using a non-invasive method. Regarding treatment, the study establishes a protocol for administering high-dose glucocorticoids (0.5-0.75 mg/kg per day) to patients in the early active phase, followed by gradual tapering over 6-12 months. To reduce the high recurrence rate (30-40%), the study recommends the use of maintenance therapy with immunosuppressants such as mycophenolate mofetil (MMF) or rituximab.

Significance and Prospects

The integrated guidelines presented in this study are valuable as they provide a consistent and effective treatment pathway for patients who have previously suffered from diagnostic delays and recurrence. The precise diagnostic criteria and drug therapy regimens are expected to contribute to preventing unnecessary ureteral surgery or renal damage. However, controlling the risk of opportunistic infections and drug side effects associated with long-term immunosuppressant use remains a challenge. To fully elucidate the relationship between genetic diversity in patient populations and environmental factors such as smoking and asbestos exposure, an expansion of large-scale, multinational patient registries is needed. Future analysis of accumulated clinical data is expected to facilitate precision medicine research aimed at predicting individual patient responses to treatment.