Comparison of two subsets of Chinese patients with retroperitoneal fibrosis in terms of IgG4 immunohistochemical staining

Differences in Fibroinflammatory Activity Shown on 68Ga-FAPI-04 and 18F-FDG PET/CT in the Two Subtypes of IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a highly heterogeneous autoimmune disease. Recently, 2 subtypes of IgG4-RD, proliferative and fibrotic, were defined according to patients' clinicopathologic characteristics. The purpose of this study was to determine the difference in fibroinflammatory activity shown on 68Ga-FAPI-04 and 18F-FDG PET/CT in the proliferative and fibrotic IgG4-RD subtypes. Methods: Thirty-seven newly diagnosed IgG4-RD patients (29 of the proliferative subtype and 8 of the fibrotic subtype) who had undergone 68Ga-FAPI-04 and 18F-FDG PET/CT were enrolled. SUVmax and target-to-background ratio (TBR) of IgG4-RD lesions were measured. To evaluate the weight of fibroinflammatory activity, the PET index of a lesion was calculated as the quotient of SUVmax or TBR of 68Ga-FAPI-04 and that of 18F-FDG. For the assessment of the global disease in an individual patient, the PET index was defined as the ratio of SUVmean of all involved lesions in 68Ga-FAPI-04 PET/CT to that in 18F-FDG. Results: The 18F-FDG uptake values of the most prominent lesions in the proliferative and fibrotic subtypes were similar; however, the proliferative subtype showed significantly higher uptake of 68Ga-FAPI-04 than did the fibrotic subtype (SUVmax, 17.67 ± 7.46 vs. 10.93 ± 2.22, P = 0.005; TBR, 15.49 ± 8.23 vs. 9.25 ± 3.00, P = 0.015). The PET index of proliferative-subtype patients was higher than that of fibrotic-subtype patients (1.46 ± 0.41 vs. 1.14 ± 0.39, P = 0.039). The PET index of pancreatobiliary disease was significantly higher than that of head-and-neck disease, fibrosis or aortitis, lymph nodes, and another disease subtype (P < 0.05). After first-line treatment, patients with a PET index of at least 1.5 had significantly shorter relapse-free survival than those with a PET index of less than 1.5 (22.0 mo vs. not reached, P < 0.0001; hazard ratio, 13.46; 95% CI, 2.236-81.03). Conclusion: The proliferative subtype of IgG4-RD had a greater weight of fibroinflammatory activity than that of the fibrotic subtype. The PET index, a marker of the weight of fibroinflammatory activity, is predictive of relapse-free survival of IgG4-RD.

Idiopathic retroperitoneal fibrosis with endometrial cancer: a case report and literature review

Background

Retroperitoneal fibrosis is a rare disease characterized by chronic nonspecific inflammation, which leads to clinical compression manifestations of retroperitoneal organs especially ureter. Approximately 70 percent of retroperitoneal fibrosis cases are idiopathic which has no clear etiology. This study reported a rare case of a 48-year-old woman presented with idiopathic retroperitoneal fibrosis and endometrial cancer.

Case presentation

A 48-year-old woman presented with irregular vaginal bleeding without abdominal pain, bloating or discomfort. The patient was diagnosed iRPF after splenectomy 13 years ago. Then she took prednisone for 2 years and took tamoxifen for about 11 years. She stopped taking the medication from October 2019 to May 2020 and then started taking tamoxifen again until November 2020. Two weeks after she stopped taking tamoxifen, she presented with irregular vaginal bleeding. Gynecological ultrasound revealed a thick endometrium with uneven echo enhancement and blood flow signals. Then diagnostic curettage was performed with pathological examination showed endometroid carcinoma. Later, the patient was admitted to Peking University Third Hospital for surgery. Preoperative imaging examinations, including CT, MRI, and PET/CT, all showed pelvic enlarged lymph nodes and they were highly suspected to have lymph node metastasis. The patient underwent laparoscopic surgical staging and enlarged lymph nodes in the pelvic and aortic regions were removed. Finally, the pathology confirmed that endometrioid adenocarcinoma and fibrosis, but there was no tumor infiltration in these enlarged lymph nodes. The patient is now in good condition.

Conclusion

This case report stressed the difficulty to distinguish between lymph node metastasis and inflammatory hyperplasia by common imaging methods. Due to increased surgical difficulty among retroperitoneal patients, lymphadenectomy should be carefully evaluated to avoid additional surgical complications and over-treatment.

IgG4-Related Disease: Mimickers and Diagnostic Pitfalls

BACKGROUND

The tendency of IgG4-related disease (IgG4-RD) to form pseudotumors, as well as its multisystemic nature, makes it the perfect mimicker of many conditions. Moreover, some clinical, serological, radiological, or histological features of the disease might be shared with some mimickers.Recently, 4 clinical phenotypes have been identified, and patients grouped in each phenotype have distinctive demographic, clinical, and serological features and outcomes, and, as expected, for each phenotype, a set of differential diagnoses should be considered.

SUMMARY OF THE LITERATURE

The main differential diagnoses for the pancreato-hepato-biliary phenotype are pancreatic adenocarcinoma and cholangiocarcinoma. Other differential diagnoses include type 2 autoimmune pancreatitis and primary sclerosing cholangitis. In patients with retroperitoneal/aortic phenotype, inflammatory conditions such as idiopathic retroperitoneal fibrosis and large vessel vasculitides should be ruled out, and most of the time, a biopsy will be needed to exclude malignancies. In head and neck limited phenotype, autoimmune conditions (eg, granulomatosis with polyangiitis, Graves orbitopathy, sarcoidosis), malignancies, and histiocytosis should be ruled out, whereas the main differential diagnoses of the Mikulicz/systemic phenotype are Sjögren syndrome, granulomatosis with polyangiitis, and multicentric Castleman disease.

CONCLUSIONS

Approaching a patient with probable IgG4-RD through a clinical phenotype framework will ease the diagnostic algorithm and facilitate the prompt recognition of the disease. There are certain clinical, serological, radiological, and histological features in each clinical phenotype that, if present, increase the likelihood that a patient may have IgG4-RD instead of the mimicker condition. Those clues that point toward IgG4-RD diagnosis should be actively sought in the workup of patients.

Retroperitoneal fibrosis masquerading as pelvi-ureteric junction obstruction - Laparoscopic management

Introduction

Retroperitoneal fibrosis (RPF) is a rare fibro-inflammatory condition which is characterized by development of extensive fibrosis throughout the retroperitoneum. It is classically centred over the anterior surface of the fourth and fifth lumbar vertebrae. It results in entrapment and extrinsic compression of retroperitoneal structures.

Presentation of the case

We present the case of a 69 years old man who was reported to have right pelvi - ureteric junction obstruction on computed tomography, but turned out to have RPF.

Discussion

Retroperitoneal fibrosis commonly causes obstructive uropathy (either unilateral, bilateral or progressing from unilateral to bilateral) and if untreated, renal failure. It has high response/remission rates to glucocorticoid therapy. However, relapse rates are also high. Hence, close surveillance with serial laboratory and imaging investigations, after achieving remission, is key to long term disease control.

Conclusion

Although classical imaging findings, supportive laboratory markers and suggestive/diagnostic histopathology appearances for RPF are well documented, its accurate preoperative diagnosis is not always an assured certainty.

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This case is unique in that the original plan to perform a laparoscopic pyeloplasty, purportedly for right pelvi-ureteric junction obstruction; was aborted ‘on table’ and a laparoscopic ureterolysis performed, instead.

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Though ureteral involvement is bilateral in most cases of retroperitoneal fibrosis, this case is rare and unique in that the patient had unilateral involvement of his ureter (right sided).

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Periaortic fibro-inflammatory mass at the level of the lumbar vertebrae is the hallmark of primary / idiopathic retroperitoneal fibrosis. However in this case, no such imaging finding was noted. Instead, the patient had just obvious unilateral (ride sided) disease on pre-operative imaging.