Imaging appearance of fibrosing diseases of the retroperitoneum: can a definitive diagnosis be made?

Multimodality imaging review of retroperitoneal fibrosis

Retroperitoneal fibrosis (RPF) is a rare fibroinflammatory disease with idiopathic and secondary causes. Idiopathic disease is more common and is believed to be immune mediated; associations with autoimmune diseases and/or inflammatory disorders such as IgG4 related disease are often present. Common complications include hydronephrosis and venous stenosis and/or thrombosis. Due to its nonspecific clinical presentation, imaging is vital for diagnosis; in addition, imaging may help distinguish idiopathic from secondary causes and can aid in distinguishing early/active disease from chronic/inactive disease. Magnetic resonance imaging is the preferred imaging modality to stage and monitor the disease, though CT and PET/CT imaging may also be of value. While the imaging findings can overlap with other diseases, there are some characteristic findings which can favor RPF. However, a biopsy is needed for a definitive diagnosis.The following article discusses the clinical features, imaging appearances across modalities, associated complications, potential diagnostic pitfalls, and treatment approaches for RPF. The role of advanced imaging techniques, such as diffuse weighted imaging and 18F-FDG PET/MRI, in the evaluation of RPF will also be included.

Clinical characteristics of IgG4-related retroperitoneal fibrosis in a cohort of 117 patients with idiopathic retroperitoneal fibrosis: a retrospective study

OBJECTIVE

Retroperitoneal fibrosis (RPF) is a rare condition marked by inflammation and fibrosis affecting the peritoneal and retroperitoneal soft tissues. In recent years, the identification of IgG4-related diseases has brought to light a significant association with fibrous disorders, including RPF, which were once considered independent. In this comprehensive cohort study, we performed a comparative analysis of the demographic, clinical, laboratory, histopathological, and therapeutic characteristics between patients with IgG4-related RPF and those with idiopathic retroperitoneal fibrosis (iRPF).

METHODS

We performed a retrospective analysis of 117 patients diagnosed with RPF at the First Affiliated Hospital of Naval Medical University between July 2007 and July 2023.

RESULTS

Demographic, clinical, laboratory, histopathological, and therapeutic characteristics of 70 iRPF patients and 47 IgG4-related patients were systematically compared. The IgG4-related group exhibited an older age of onset, with a predominant occurrence among adult males. Significantly elevated levels of eosinophilia and IgE were observed in the IgG4-related group. Most patients across both groups displayed elevated CRP and ESR levels. Furthermore, at the time of diagnosis, the IgG4-related group had higher serum creatinine and lower levels of complement. The most prevalent clinical manifestation in both groups was flank pain. The proportion of lymphoplasmic infiltration and storiform fibrosis in IgG4-related RPF group was significantly higher. The IgG4-related RPF group had significantly higher IgG4-positive plasma cell count, IgG4/total IgG ratio, and eosinophils count than that in iRPF group.

CONCLUSION

We conducted a comparative analysis of demographic, clinical, laboratory, histopathological, and therapeutic differences between the iRPF patients and the IgG4-related patients. Clarifying the distinctive characteristics of these two groups will contribute to a better understanding of the condition and facilitate the development of specific treatment strategies tailored to each group. Key Points • Identification of distinct clinical features and outcomes between IgG4-related and iRPF patients in a large retrospective study.

Multimodality pictorial review of IgG4-related disease in the abdomen and pelvis

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a systemic, immune-mediated disease that can affect multiple organs, including the orbits, salivary glands, thyroid gland, lungs, aorta, pancreas, bile ducts, lymph nodes, and retroperitoneum. While timely diagnosis is particularly important given the efficacy of glucocorticoid treatment for IgG4-RD, accurate recognition can prove a challenge given the overlap between the imaging features of this disease and other entities.

PURPOSE

After a review of the epidemiology, pathophysiology, and clinical considerations (including treatment) associated with IgG4-RD, this pictorial review will showcase the variable imaging manifestations of this disease in the abdomen and pelvis. Post-treatment imaging appearance of these entities will be reviewed and mimickers of this disease in the abdomen and pelvis will be presented.

CONCLUSION

The presence of mass-like soft tissue with radiographic characteristics of fibrosis affecting multiple organs should raise suspicion for IgG4-RD, although definite diagnosis can only be made with appropriate clinical, serological, and pathologic data.

Chronic periaortitis: A clinical approach

Chronic periaortitis (CP) is a rare disease characterised by the presence of a fibro-inflammatory tissue typically enveloping the abdominal aorta, the iliac arteries and, in some cases, the nearby structures, such as the ureters and the inferior vena cava. Imaging plays a key role in the diagnosis and follow-up: computed tomography and magnetic resonance imaging scans are used to define the extension of the pathological tissue, whereas fluorodeoxyglucose positron emission tomography is the gold standard to establish the degree of its metabolic activity. CP must be distinguished from secondary forms of periaortic infiltration, which include malignant, infectious, and drug-related aetiologies. This review focuses on the clinical aspects of CP and the differential diagnosis with secondary cases, and aims to provide the clinician with a guide through this challenging clinical approach.

Multimodality imaging of renal lymphoma and its mimics

Lymphomatous involvement of the genitourinary system, particularly the kidneys, is commonly detected on autopsies; yet on conventional diagnostic imaging renal lymphoma is significantly underestimated and underreported, in part due to its variable imaging appearance and overlapping features with other conditions. We present a spectrum of typical and atypical appearances of renal lymphoma using multimodality imaging, while reviewing the roles of imaging in the detection, diagnosis, staging, and surveillance of patients with lymphoma. We also illustrate a breadth of benign and malignant entities with similar imaging features confounding the diagnosis of renal lymphoma, emphasizing the role of percutaneous image-guided biopsy. Understanding the spectrum of appearances of renal lymphoma and recognizing the overlapping entities will help radiologists improve diagnostic confidence and accuracy.

Including Medical Management in the Urologic Approach to Idiopathic Retroperitoneal Fibrosis

OBJECTIVE

To characterize the timing and effectiveness of medical management in resolving stent-dependent ureteral compression secondary to idiopathic retroperitoneal fibrosis (RPF), the long-term relevant outcomes, and the side effects of treatment.

METHODS

A retrospective review of RPF patients diagnosed from 2002-2018 was performed. Patients with hydronephrosis due to ureteral involvement that were managed with medication and with temporary stenting as needed, but without initial ureterolysis, were included. Patient demographics and RPF management details were obtained, including the following subsequent events: ureterolysis, nephrectomy, recurrent upper tract obstruction, and medication side effects.

RESULTS

Fifty-two patients met inclusion criteria. Resolution of ureteral obstruction with medical management and temporary renal drainage as needed occurred in 36 (69%) patients with a median stent duration of 16 months, and median clinical and radiographic follow up of 4.2 and 3.3 years, respectively. Recurrent obstruction after a stent-free period occurred in 9 (18%) patients. Ureterolysis was performed in 8 (15%) patients at a median of 2.2 years for medication intolerance, lack of radiographic response to medication, or persisting pain. Potential medication side effects occurred in 6 (12%) patients.

CONCLUSIONS

Medical management supported successful resolution of ureteral obstruction in 69% of patients without the need for ureterolysis after temporary renal drainage using stents, with rare incidence of worsening renal dysfunction or medication side effect. To date, this is the largest reported series of systematically managed RPF patients with obstructive uropathy receiving initial medical therapy and serves to counsel patients and advise urologists and nephrologists of the expected course and advantages and disadvantages of medical versus surgical management.

Idiopathic retroperitoneal fibrosis: an update for nephrologists

Idiopathic retroperitoneal fibrosis (IRF) is a rare condition characterized by the development of a peri-aortic and peri-iliac tissue showing chronic inflammatory infiltrates and pronounced fibrosis. Ureteral entrapment with consequent obstructive uropathy is one of the most common complications of IRF, which can lead to acute renal failure and, in the long term, to varying degrees of chronic kidney disease. IRF may be isolated or develop in association with autoimmune diseases (e.g. Hashimoto's thyroiditis and psoriasis) and other fibro-inflammatory disorders (often within the spectrum of immunoglobulin G4-related disease), which suggests that it should be considered as a potentially systemic condition. IRF is an immune-mediated disease: genetic variants (e.g. human leukocyte antigen (HLA)-DRB1*03) and environmental agents (mainly exposure to asbestos and smoking) are strongly associated with an increased risk of developing the disease, while a complex network of chemokines (e.g. CXCL12 and C-C moti chemokine 11 (CCL11)) and cytokines [e.g. interleukin (IL)-6, IL-12 and IL-13] is likely to orchestrate the inflammatory response and simultaneously promote fibrosis. Glucocorticoids, alone or in combination with traditional immunosuppressants such as methotrexate and mycophenolate mofetil, are usually efficacious and promptly induce disease remission; however, up to 50% of patients relapse, thus requiring repeat immunosuppressive courses. Biologic drugs, namely rituximab, are being explored for the treatment of IRF. In addition to medical therapies, interventional procedures (mainly ureteral stenting) are required to relieve ureteral obstruction, whereas surgical ureterolysis is generally reserved to refractory cases. If appropriately treated, then the overall and renal prognosis of IRF are good, with <5% patients developing end-stage renal disease.

IgG4-related disease in the abdomen and pelvis: atypical findings, pitfalls, and mimics

IgG4-related disease (IgG4-RD) is a systemic, autoimmune, fibroinflammatory disease that can cause multi-organ damage. Although there have been many trials and studies since its recognition in 2003, there is still much that is unknown. Furthermore, IgG4-RD can affect any organ in the body and often has many mimics and alternative diagnoses, which can make for a challenging workup. Imaging plays a substantial role in the diagnosis of IgG4-RD and is often the first occasion where IgG4-RD comes into consideration. Thus, knowledge about the imaging findings of various manifestations of IgG4-RD can aid in the diagnosis and have a significant impact on patient management. In this article, we review the wide array of imaging findings, both typical and atypical, as well as possible mimics of IgG4-RD in the abdomen and pelvis.

An atypical manifestation of idiopathic retroperitoneal fibrosis: A case report

A 58-year-old male patient, previously healthy, presented with right flank pain of few hours duration. Initial workup showed an elevated creatinine and right hydroureteronephrosis. Computed tomography imaging revealed a retroperitoneal soft tissue mass encasing the right common iliac artery which is a first reported case in its anatomical distribution. Patient was referred to interventional radiology service where a percutaneous nephrostomy tube was placed followed by double J stenting. Subsequently, treatment with steroids was started. Follow up imaging a few months later revealed progressive resolution of the inflammatory process.

Idiopathic Retroperitoneal Fibrosis: Long-term Risk and Predictors of Relapse

RATIONALE & OBJECTIVE

Idiopathic retroperitoneal fibrosis (IRF) is a rare disorder of unknown cause. Medical therapy can induce remission, but disease relapses are common. This study sought to characterize long-term outcomes of IRF and the factors associated with disease recurrences.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Retrospective analysis of 50 patients with IRF prospectively followed up for 8.9 (IQR, 4.7-12.7) years at a tertiary-care referral center.

EXPOSURES

Demographic, clinical, treatment, and laboratory parameters, including measures of autoimmunity.

OUTCOME

Disease relapse.

ANALYTICAL APPROACH

Proportional hazards analysis for the subdistribution of competing risks.

RESULTS

49 patients received medical treatment and 35 underwent interventional procedures. All patients experienced a clinical response (defined as regression of disease-related symptoms and hydronephrosis, and decrease in the maximal transverse diameter of the retroperitoneal mass on computed tomography of >50%), 44 of whom responded within 1 year. The remaining 6 responded over a median of 2.95 years after starting therapy. 40 patients were alive at last observation, 1 receiving maintenance dialysis and 15 with estimated glomerular filtration rate < 60mL/min/1.73m². Patient survival at 5, 10, and 15 years was 95%, 84%, and 68%, respectively. 19 (38%) patients had at least 1 relapse (occurring a median of 5.19 years after starting therapy), defined as an increase in serum creatinine level of at least 30% or recurrence/development of hydronephrosis and ≥20% increase in the maximal transverse diameter of the retroperitoneal mass on computed tomography. Cumulative incidences of relapse at 5, 10, and 15 years were 21%, 41%, and 48%, respectively. Baseline antinuclear antibody positivity and male sex were associated with relapse (subdistribution hazard ratios [sHRs] of 5.35 [95% CI, 2.15-13.27] and 4.94 [95% CI, 1.32-18.57], respectively), while higher corticosteroid therapy dosage at 1 year (sHR for relapse per 1-mg/d greater dosage, 0.91 [95% CI, 0.84-0.98]) and treatment with prednisone alone or with tamoxifen (sHR for relapse of 0.25 [95% CI, 0.07-0.85] vs other therapies) were associated with lower rate of relapse.

LIMITATIONS

Small sample size and variable approaches to therapy.

CONCLUSIONS

IRF relapses were common and were experienced more frequently by male patients. Corticosteroids alone or with tamoxifen were associated with a lower rate of relapse. The strong association of antinuclear antibody positivity with relapse supports the hypothesis of an autoimmune pathogenesis of IRF.

Retroperitoneal Leiomyosarcoma From the Radiologic Pathology Archives

Leiomyosarcoma is a malignant neoplasm that shows smooth muscle differentiation. It is the second most common sarcoma to affect the retroperitoneum. Retroperitoneal leiomyosarcomas may grow to large sizes before detection and may be an incidental finding at imaging. When symptomatic, retroperitoneal leiomyosarcoma may cause compressive symptoms, including pain. Retroperitoneal leiomyosarcoma most commonly manifests as a large soft-tissue mass, with areas of necrosis. The most frequent pattern of growth is an entirely extravascular mass. Less commonly, leiomyosarcoma may demonstrate both extravascular and intravascular components. Rarely, retroperitoneal leiomyosarcomas are completely intravascular, typically arising from the inferior vena cava. Given its variable imaging features, a large variety of neoplastic and nonneoplastic conditions are included in the differential diagnosis of retroperitoneal leiomyosarcoma. In this review, the authors discuss retroperitoneal leiomyosarcoma, with emphasis on the pathologic basis of disease, and illustrate the multimodality imaging appearances of retroperitoneal leiomyosarcoma using cases from the Radiologic Pathology Archives of the American Institute for Radiologic Pathology. The authors review important differential considerations of retroperitoneal leiomyosarcoma, focusing on the extravascular pattern of growth, and emphasize clinical and imaging features that help radiologists differentiate leiomyosarcoma from the most frequent mimics. The information presented in this review will aid radiologists in fulfilling their key roles in the diagnosis, operative planning, and follow-up of patients with retroperitoneal leiomyosarcoma.