Organ Correlation in IgG4-Related Diseases

IgG4-related disease: an update on pathology and diagnostic criteria with a focus on salivary gland manifestations

Immunoglobulin G4-related disease (IgG4-RD) is a multi-organ disorder characterized by a highly variable clinical presentation depending on the affected organ/s, extent of tumefactive fibroinflammatory lesions, and associated functional impairment. The disease pursues a chronic, relapsing, often asymptomatic course and hence may pose a significant diagnostic challenge. Diagnostic delay can lead to progressive fibrosis and irreversible organ damage resulting into significant morbidity and even mortality. Given its broad clinical spectrum, physicians of all specialties may be the first clinicians facing this diagnostic challenge. Outside the pancreatobiliary system, the head and neck represents the major site of IgG4-RD with variable organ-specific diffuse or mass-forming lesions. In up to 75% of cases, elevated serum IgG4 levels are observed, but this figure possibly underestimates the fraction of seronegative cases, as the disease manifestations may present metachronously with significant intervals. Together with negative serology, this can lead to misdiagnosis of seronegative cases. A standardized nomenclature and diagnostic criteria for IgG4-RD were established in 2012 and revised in 2020 facilitating scientific research and expanding the range of diseases associated with IgG4 abnormalities. In addition to orbital pseudotumor, dacryoadenitis, Riedel thyroiditis, sinonasal manifestations, and rare miscellaneous conditions, IgG4-related sialadenitis is one of the most frequent presentations in the head and neck region. However, controversy still exists regarding the relationship between sialadenitis and IgG4-RD. This review focuses on the clinicopathological features of IgG4-related sialadenitis and its contemporary diagnostic criteria.

Systemic Involvement in Immunoglobulin G4-Related Ophthalmic Disease

BACKGROUND

Immunoglobulin G4-related ophthalmic disease (IgG4-ROD) poses clinical challenges due to its heterogeneous ocular and systemic manifestations. We aim to report the systemic involvement and the clinical, serological and radiological associations of a cohort of Chinese patients.

METHODS

A territory-wide, biopsy-proven, Chinese cohort. A retrospective, masked chart review of medical records, orbital images, and histopathology reports.

RESULTS

A total of 122 (65 male) patients with a follow-up of 81 ± 49 (24 to 84) months were reviewed. Ninety (74%) patients presented bilaterally. Subacute upper eyelid swelling was the commonest presentation (82/122, 67%). During follow-up, 91/122 patients (75%) underwent extra-orbital imaging including computer tomography (692 films), ultrasonography (182 films), magnetic resonance imaging (76 films) and whole body FDG-PET scan (33 films). Eighty-six (95%) of these 91 patients had extra-orbital involvement radiologically (2.7 ± 1.6 regions, range: 0 to 9). Lymph node was the most prevalent (N = 60,66%), followed by salivary gland (N = 51,56%), lung (N = 49,54%), kidney (N = 22, 24%), hepatobiliary tree (N = 18, 20%) and pancreas (N = 17, 19%). Other organs include thyroid, aorta, meninges/brain and skin. Twenty-eight (23%) patients had allergic diseases (19 asthma, 16 allergic rhinitis, and 6 eczemas). Fifty-seven (48%) patients had paranasal sinusitis. Serum eosinophilia was associated with a higher number (3.24 versus 2.52, P = 0.0304) of organ involvement. Patients with deep organ involvement was associated with a higher age of IgG4-ROD onset (70 ± 12 versus 56 ± 13, P < 0.0001).

CONCLUSIONS

95% of the patients who underwent systemic imaging in our cohort had systemic organ involvement. An early physicians' assessment and radiological imaging are recommended after the diagnosis of IgG4-ROD.

Performance of classification and diagnostic criteria for IgG4-related disease and comparison of patients with and without IgG4-related disease

IgG4-related disease (IgG4-RD) was recently described in Japan. It is characterised by extensive organ involvement with tissue fibrosis. We assessed the performance of the 2019 American College of Rheumatology and European League Against Rheumatism (ACR/EULAR) classification criteria and the 2020 revised comprehensive diagnostic (RCD) criteria as well as differences between patients with and without IgG4-RD. In this retrospective, single-centre study of 50 patients admitted with suspected IgG4-RD, we evaluated the sensitivity and specificity of both criteria. We also compared clinical characteristics and laboratory data of patients with IgG4-RD (n = 42) and patients without IgG4-RD (n = 8). The ACR/EULAR classification criteria had 88.1% sensitivity and 87.5% specificity for IgG4-RD diagnosis. The RCD criteria had 100% sensitivity and 50% specificity. Patients with IgG4-RD had significantly more affected organs (p = 0.002). Patients with a single affected organ and IgG4-RD had significantly higher serum IgG4/IgG ratios (p = 0.027), lower serum C-reactive protein levels (p = 0.020), and lower total haemolytic complement activity (p = 0.044) than those without IgG4-RD. The ACR/EULAR classification criteria have high specificity and the RCD criteria have high sensitivity for diagnosing IgG4-RD. The number of affected organs is important for diagnosing IgG4-RD.

Pancreaticobiliary versus head and neck presentation of immunoglobulin G4-related disease: different sides of the same coin?

BACKGROUND AND STUDY AIM

Immunoglobulin G4-related disease (IgG4-RD) is a rare immune mediated fibroinflammatory condition. Pancreaticobiliary (PB) and head and neck (HN) are two of the most commonly involved anatomical sites. It has been postulated that PB IgG4-RD and HN IgG4-RD have distinct clinical phenotypes. Whether the optimum treatment regimen or response to therapy differs between them is unknown. We aimed to assess differences between PB and HN IgG4-RD in a cohort of IgG4 disease managed by an IgG4-RD multispecialty team.

METHODS

We performed a retrospective study of a prospectively maintained multidisciplinary IgG4-RD database to identify patients diagnosed with PB and HN IgG4-RD (based on initial presentation) between 2005 and 2019. The electronic patient records were reviewed. Use of immunosuppressive agents and clinical course was analysed.

RESULTS

60 patients with PB IgG4-RD and 14 with HN IgG4-RD were included in the study. PB IgG4-RD was associated with older age at diagnosis 64 versus 51 years (p<0.001), higher serum IgG4 level as a multiple of upper limit of normal median (IQR) 2 (1-3.75) vs 1 (1-2), (p=0.04) and greater proportion with more than one organ involved 68% vs 33% (p=0.03). HN IgG4-RD was more likely to receive second-line therapy 71% versus 36% (p=0.03). Persistent elevation of serum IgG4 after therapy was more common in PB IgG4-RD 84% versus 43% (p=0.03).

CONCLUSION

These findings support the contention that PB IgG4-RD and HN IgG4-RD have different clinical profiles and represent distinct subtypes of IgG4-RD.

A case of immunoglobulin G4-related sclerosing mesenteritis without other organ involvement

A 64-year-old man presented to our hospital with abdominal pain and 4-5 episodes of watery diarrhea per day for 2 months. Abdominal ultrasound examination revealed a mass in the peritoneal cavity, and computed tomography showed a 13.4 cm mass in the mesentery and a 3 cm mass in the mesocolon. The patient underwent laparoscopic partial resection for diagnosis. Microscopically, abundant fibrosis and numerous immunoglobulin (Ig) G4-positive plasma cells were observed. The serum level of IgG4 was 665 mg/dl postoperatively. These findings suggested that the lesion was consistent with IgG4-related sclerosing mesenteritis. Oral steroids resulted in rapid disappearance of symptoms and a decrease in masses. Recently, sclerosing mesenteritis are reported as IgG4-related disease or mimicking IgG4-related disease but multiple lesions rarely occur in the same organ. We report a case of IgG4-related sclerosing mesenteritis with multiple lesions without involvement of other organs, such as the pancreas and salivary glands.

The prevalence of extra-salivary gland complications in immunoglobulin G4-related sialadenitis

OBJECTIVES

To estimate the prevalence of extra-glandular lesions in patients with immunoglobulin G4-related sialadenitis (IgG4-RS).

METHODS

Six electronic databases (PubMed, EMBASE, Science Direct, Scopus, Web of Science, and China National Knowledge Infrastructure) were systematically searched from the date of inception of each database to March 2021. The Strengthening the Reporting of Observational Studies in Epidemiology statement was used to conduct methodological quality assessment, and a random-effect meta-analysis model was applied to estimate the prevalence. Publication bias was visually assessed using a funnel plot and calculated via Begg's and Egger's tests. The Stata 15 software was used to perform data analysis.

RESULTS

A total of 43 articles comprising 1,864 patients with IgG4-RS were considered to be eligible for this study. The pooled prevalence of extra-salivary gland lesions in IgG4-RS was 76.53% with a confidence interval (CI) of (69.39%, 83.04%). A higher prevalence was associated with studies published before or during 2015 (84.38%, CI [74.23%, 92.58%]) than those published after 2015 (68.55%, CI [58.44%, 77.88%]). Lacrimal gland involvement (54.68%, CI [45.61%, 63.60%]) and lymph node swelling (56.96%, CI [48.16%, 65.56%]) were the most frequent lesions.

CONCLUSIONS

Extra-glandular lesions were common in patients with IgG4-RS. More high-quality prospective studies with less heterogeneity are required to determine the accurate prevalence.

Serum free light chain assessment in type 1 autoimmune pancreatitis

BACKGROUND

/Object: Some patients with type 1 autoimmune pancreatitis (AIP), the pancreatic manifestation of IgG4-related disease, have normal serum IgG4. The aim of this study is to investigate the diagnostic value of measuring serum free light chains (FLCs) in type 1 AIP.

MATERIALS AND METHODS

Thirty-seven patients with type 1 AIP, and 21 healthy, 17 alcoholic chronic pancreatitis (ACP), 21 idiopathic chronic pancreatitis (ICP) and 20 pancreatic cancer (PC) patients were enrolled. Serum IgG4 and FLC concentrations were measured using sFLC Freelite assays on a nephelometric analyzer.

RESULTS

Active AIP patients have significantly higher serum levels of κ (median 30.97 (12.3-227.0) mg/L) and λFLC (median 20.53 (12.36-102.7) mg/L)) than healthy controls (κFLC; median 12.5 (3.1-52.1) mg/L), λFLC: median 12.45 (5.4-39.5) mg/L) (p < 0.05) correlating with raised serum IgG4, and significantly higher summated FLCs (∑) (median 53.09 (25.0-218.0) mg/L) than ICP patients (median 26.77 (15.0-89.2) mg/L) and healthy controls (median 24.43 (8.5-91.6) mg/L) (p < 0.05). AIP patients (median 1.43 (0.84-3.24)) showed significantly higher κ/λ ratios than ACP (median 0.83 (0.42-1.18)), ICP (median 0.87 (0.47-2.16)), PC patients (median 0.90 (0.48-1.27)) and healthy controls (median 0.963 (0.51-1.32)). There was a correlation between increased κ and λ FLCs levels and the number of affected organs involved in IgG4 related disease.

CONCLUSION

Patients with type 1 AIP have increased serum k and λ FLC concentrations, Σ FLC, and κ/λ ratios. These novel biomarkers may be useful in the diagnosis of type 1 AIP and in monitoring disease activity.

IgG4-Related Disease with Selective Testicular Involvement- A Rare Entity: Case Report with Review of Literature

Immunoglobin-G4 related disease (IgG4-RD) is an auto-immune inflammatory condition where patients present with a tumour-like mass that shows infiltration by plasma cell and subsequent fibrosis. It is a systemic condition that primarily involves the salivary glands, pancreas, kidneys, aorta, and retroperitoneum amongst other organs. Testicular involvement is a rare occurrence in this disease entity. A 55-year old male patient presented with the complaints of pain and swelling in the right scrotal region. Right-sided orchidectomy was carried out which on histopathology showed features suggestive of IgG4-RD which was later confirmed on immunohistochemistry. Whole body MRI revealed that no other organ was involved in the disease process in this patient. IgG4-RD has a variable clinical course and considerable overlap with its differentials. Imaging studies and serum IgG4 levels are neither confirmatory nor customarily diagnostic in every case. The only confirmatory diagnostic investigation is histopathological examination, which shows infiltration of IgG4+ plasma cells and fibrosis in the involved tissue. Whenever a mass-forming lesion with typical histomorphological features is encountered with involvement of multiple organs/anatomic sites, IgG4-related disease should be considered among the differentials, and clinicians of all disciplines should be familiar with this disease entity.

Salivary gland involvement disparities in clinical characteristics of IgG4-related disease: a retrospective study of 428 patients

OBJECTIVES

IgG4-related disease (IgG4-RD) has recently been recognized as a fibro-inflammatory condition featuring tumefactive lesions in multiple organs, and the salivary gland is one of the most commonly involved sites. We undertook this study to compare detailed demographic, clinical and laboratory characteristics of IgG4-RD patients with salivary gland lesions (IgG4-RD SG+) and salivary-gland-free IgG4-RD (IgG4-RD SG-) in a large cohort.

METHODS

We carried out a retrospective review of the medical records of 428 cases of IgG4-RD diagnosed at Peking University People's Hospital between March 2006 and May 2018.

RESULTS

Among 428 patients, 249 had salivary glands that were affected. IgG4-RD SG+ patients showed younger age at disease onset and diagnosis, and a longer interval between symptom onset and diagnosis. The IgG4-RD SG+ group involved more female patients, and allergic diseases were more common in this group. In terms of organ involvement, the IgG4-RD SG+ group were more frequently presented with lacrimal gland involvement, while lymph node, retroperitoneal fibrosis, pancreas, biliary system, kidney and aorta were more prominent in the IgG4-RD SG- group. In addition, the serum IgG4 level, IgG4/IgG ratio and IgE level were significantly higher in IgG4-RD SG+ patients. Patients with eosinophilia were more common in the IgG4-RD SG+ group, while elevated ESR, CRP and positive ANA were more common in the IgG4-RD SG- group.

CONCLUSION

We have revealed demographic, clinical and laboratory differences between IgG4-RD SG+ and SG- patients, which indicated potential differences in pathogenesis and important implications for the diagnosis and management of these two phenotypes.

IgG4 sclerosing disease of the esophagus: a case-based review

IgG4-related disease (IgG4-RD) is an inflammatory and fibrosing disease which causes tumor-like swelling of organs and commonly mimics symptoms of malignancy. It has been increasing in prevalence in the last decade, but esophageal involvement remains rare. IgG4-RD was first known to involve certain organs, such as the pancreas. It has, since, been described as a systemic disease process. IgG4-RD should be considered in patients presenting with dysphagia. Initiation of appropriate treatment with corticosteroids can avoid unnecessary procedures and improve outcomes. The aim of this review is to discuss 17 cases of IgG4-RD of the esophagus. Literature review was conducted using NCBI database (PMC and PubMed filters) using the keywords "IgG4 disease," "sclerosing," "esophagus" and "gastrointestinal." The search was narrowed to include cases describing IgG4 disease of the esophagus using the same filters. Literature review identified 16 documented cases of IgG4-RD involving the esophagus. Upon literature review, it remains clear that it is extremely rare for IgG4-RD to affect the esophagus. Sixteen cases have been reported. We present a 17th case and discuss the implications of IgG4-RD. It is important to keep a broad differential diagnosis that includes IgG4-RD for patients presenting with dysphagia, especially when symptoms are refractory.

Clinical outcomes and predictive relapse factors of IgG4-related disease following treatment: a long-term cohort study

OBJECTIVES

The aim of this study was to investigate the predictive factors for relapse of IgG4-related disease (IgG4-RD) and observe the long-term clinical outcomes in patients with IgG4-RD.

METHODS

We included in the present analysis 122 patients who were newly diagnosed with IgG4-RD, treated with glucocorticoid (GC) monotherapy or GC and immunosuppressant combination therapy, and followed for at least 3 years. Clinical relapse, response and side effects were recorded.

RESULTS

The cumulative relapse rates of patients in this study were 10.66%, 22.95% and 27.87% at 12, 24 and 36 months, respectively. Complete drug withdrawal was an independent risk factor for disease relapse. Higher serum IgG4 concentrations, involvement of more organs, higher IgG4 RI scores and elevation of eosinophils at baseline were closely associated with disease relapse. Re-elevation of serum IgG4 concentrations and low GC maintenance dosage during the follow-up period were significantly associated with clinical relapse. The GC dosage should be more than 6.25 mg day^-1 as monotherapy during the maintenance stage; moreover, combining with immunosuppressants can reduce the GC dosage. Adding GC or immunosuppressants for patients with re-elevation of serum IgG4 levels could prevent later disease relapse. No serious complications were noted during long-term follow-up.

CONCLUSIONS

The combination of GC with immunosuppressants was more effective than GC monotherapy during the steroid tapering and maintenance stages. Higher serum IgG4 levels, involvement of more organs, higher IgG4 RI scores, history of allergy, eosinophil elevation at baseline, re-elevation of serum IgG4 levels and lower GC maintenance dosage at follow-up might be predictive of relapse.

Pancreatobiliary Versus Head and Neck Manifestations in Immunoglobulin G4-related Disease: Distinct Subsets of the Same Disease?

OBJECTIVES

We compared the clinical profiles and organ manifestations of the commonly encountered immunoglobulin G4-related diseases (IgG4-RDs) on either side of the diaphragm: head and neck (HN) versus pancreatobiliary (PB) in IgG4-RD.

METHODS

From the Mayo Clinic, Rochester, database, we identified 53 HN and 88 PB IgG4-RD based on the first affected organ manifestation.

RESULTS

Compared with HN IgG4-RD, subjects with PB IgG4-RD were likely to be older (median, 64.8 vs 50.2 years; P < 0.0001), male (83% vs 60.4%; P = 0.003), and with a shorter duration of follow-up (24.4 vs 48.7 months; P < 0.0001). In HN versus PB-IgG4-RD orbital, lacrimal gland, submandibular, parotid gland, asthma, and sinusitis manifestations were more common (77% vs 4.5%, 21% vs 0%, 32% vs 8%, 13% vs 0%, 36% vs 9%, and 51% vs 6.8%; P < 0.0001, respectively), whereas lung manifestations were similar (13.2% vs 5.6%; P = 0.12). In contrast, in PB versus HN IgG4-RD, pancreas and biliary were more frequent (98.8% vs 15%, 56.8% vs 3.7%; P < 0.0001), whereas renal lesions were similar (12.5% vs 7.5%; P = 0.36).

CONCLUSION

Pancreatobiliary and HN IgG4-RD have distinct clinical profiles. Proximity matters in other organ involvement in IgG4-RD, and organs involved tend to cluster close to each.

New insights into immune cells cross-talk during IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a newly acknowledged entity, characterized by an immune-mediated fibro-inflammatory process affecting virtually all organs, with infiltration of IgG4⁺ bearing plasma cells. Until today the pathogenesis of IgG4-RD remains unknown. Treatment with anti-CD20 monoclonal antibodies efficiently induced remission and attenuated the secretory phenotype of myofibroblasts responsible of uncontrolled collagen deposition. This supports the pathogenic role of the adaptive immunity, particularly B cell compartment and B cell/T cell interaction. Latest studies have also highlighted the importance of innate immune system that has been underestimated before and the key role of a specific T cell subset, T follicular helper cells that are involved in IgG4-class-switching and plasmablast differentiation. In this review, we aim to review the most recent knowledge of innate immunity, T and B cells involvement in IgG4-RD, and introduce tertiary lymphoid organs (TLO) as a potential marker of relapse in this condition.

Clinical features of IgG4-related rhinosinusitis

PURPOSE

IgG4-related disease is a systemic disease that affects various organs of the body. Aim of this study is to elucidate the clinical characteristics of IgG4-related rhinosinusitis.

MATERIAL AND METHODS

Clinical features, laboratory findings, radiological and endoscopic findings, associated disease, treatment and prognosis were retrospectively examined in 10 patients with IgG4-related rhinosinusitis.

RESULTS

The age was 59.1±11.3 years old and male-to-female ratio was 1:1. The chief nasal complaints were hyposmia (n=4), nasal obstruction (n=3), and nothing (n=3). Serum IgG4 levels were elevated in all patients and the value was 740.4±472.4mg/dl. Other IgG4-related diseases were associated in all 10 patients, including IgG4-related sialadenitis (n=6), IgG4-related dacryoadenitis (n=5), and autoimmune pancreatitis (n=5). Imaging findings on CT/MRI were obstruction of the way of elimination (n=10), thickening of the sinus mucous membrane (n=10), and fluid in the sinus (n=6). All of the cases had bilateral findings. Nasal endoscopic findings were chiefly deviated nasal septum (n=5), polyps (n=4), edema of the mucous membrane (n=3). Histologically, abundant infiltration of IgG4 positive plasma cell and lymphocyte and an elevated IgG4+/IgG+ cell ration was detected in all 8 patients and 5 patients, respectively. Endoscopic sinus surgery was performed in 8 patients. Eight patients were treated with steroid therapy for other associated IgG4-related diseases. Symptoms improved in all 6 patients after an initial treatment (endoscopic surgery (n=5) and steroids (n=1)), but one patient suffered relapse.

CONCLUSIONS

IgG4-related rhinosinusitis is a distinct entity of IgG4-related disease, and is associated in patients with multiple IgG4-related diseases.

Ultrasonography for Preoperative Diagnosis of Retroperitoneal Fibrosis

This study aimed to assess the application of ultrasonography for preoperative diagnosis of retroperitoneal fibrosis (RPF). A total of 51 patients with clinically suspected RPF underwent transabdominal ultrasonography and ultrasound-guided histopathologic biopsy (tAU-UGHB). Retroperitoneal fibrosis was diagnosed in 35 patients; of these, 31 cases (88.6%) received a diagnosis using tAU-UGHB. The ultrasonographic images mainly showed solid, irregular isoechoic masses, which were present behind the retroperitoneum and surrounded the abdominal aorta, inferior vena cava, and ureters and had clear borders with the encapsulated structures. Compared with other retroperitoneal lesions, RPF lesions were mainly located below the initial level of the renal artery, and their internal flow signals were not rich (P < 0.05). Retroperitoneal fibrosis had characteristic ultrasonographic features, and color Doppler ultrasound-guided biopsy could be positioned accurately, safely, and efficiently; therefore, tAU-UGHB can be used as an effective modality for preoperative diagnosis of RPF.

Types of Organ Involvement in Patients with Immunoglobulin G4-related Disease

Background:

Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized systemic disease that can involve multiple organs and various clinical phenotypes. The purpose of this study was to analyze different types of organ involvement in IgG4-RD patients in China.

Methods:

We conducted a prospective cohort study on IgG4-RD patients to analyze the clinical manifestations and rare features of IgG4-RD. Patients were grouped into different types according to organ involvement regarding organ number and organ site. The constituent ratio in different types was also analyzed.

Results:

A total of 200 IgG4-RD patients, with a male:female ratio of 2.08:1, were grouped into different types. Cases having involvement of two or three organs were the most common whereas the fewest number of patients had multi-organ (≥4) involvement. Serum IgG4 and IgE levels, IgG4/IgG ratio, and percentage of eosinophils increased as the number of involved organs increased. In addition, constituent ratio analysis revealed that patients with salivary gland/lacrimal gland swelling, who also constituted the largest number of IgG4-RD patients, had higher serum IgG4 concentrations and IgG4/IgG values, had higher percentage of Eos, and were more likely to have had a history of allergies relative to patients with internal organ involvement.

Conclusions:

The characteristic feature of IgG4-RD is multiple organ involvement with various clinical manifestations and different types. Although serum IgG4 levels increased with the number of involved organs, serum IgG4 levels were higher for those patients with salivary gland/lacrimal gland swelling compared with those with internal organ involvement. Thus, valuable clues to the differential diagnosis of IgG4-RD could be obtained by examining the clinical patterns of organ involvement.

Poor response of initial steroid therapy for IgG4-related sclerosing cholangitis with multiple organs affected

IgG4-related sclerosing cholangitis (IgG4-SC) is a rare biliary manifestation in which many other organs might be affected. The purpose of our study was to investigate the different clinical characteristics and initial steroid response between IgG4-SC patients with and without other organs affected.A series of patients with IgG4-SC in the period from January 2006 to December 2015 at our hospital were included. The pancreas and major salivary glands were screened, and the initial corticosteroid therapy was given. Clinical information was collected and analyzed including demographics, clinical presentation, IgG4 serology, imaging features, and treatment outcomes.The study identified 72 IgG4-SC patients, including 60 males and 12 females. The mean age was 59.8 years old. Among these IgG4-SC patients, 10 patients had only bile duct involved, 42 patients had 2 organs involved and 20 patients had multiple organs involved. In patients with multiple organs involved, more complaints were given (mean 2.9 kinds), higher serum IgG4 levels were found (23458 ± 19402.7 mg/L), and more stricture lesions of biliary tract were shown. All 72 patients exhibited a disease response within 4 to 6 weeks of starting steroids. The remission rate in the multiple lesions group was lower (60%), and the recurrence rate is higher (83.3%). The relapse-free survival was 20.0 months in the single lesion group, which is longer than that in the multiple lesions group (3.1 months, P < 0.05).The IgG4-SC patients with multiple organs affected had more complaints, higher serum IgG4 levels, and poor response to initial steroids.

[Gastric cancer concurrent with IgG4-related disease: A clinical case and a review of literature]

The paper presents the data available in the literature on IgG4-related disease (IgG4-RD) concurrent with malignancies at different sites, as well as possible common pathogenetic mechanisms of their development and morphological diagnostic criteria for IgG4-RD. The authors give their own observation of gastric signet ring cell carcinoma concurrent with morphologically verified IgG4-RD.

Immunoglobulin G4-related disease mimicking an epidural spinal cord tumor: case report

The authors report a case of immunoglobulin G4-related disease (IgG4-RD) presenting as a paraspinal, epidural mass. This disease encompasses a host of autoimmune conditions that were previously thought to be separate entities. It is characterized by fibrosis, mediated by the aberrant proliferation and tissue invasion of IgG4-positive plasma cells, which can occur in any organ. As with other autoimmune conditions, it tends to be responsive to steroids and other immunosuppressants. It can rarely present as a tumefactive lesion of the central nervous system, creating the potential for misdiagnosis (given its similar radiological appearance to malignancy) and mistreatment. In 2015, a panel of experts convened to set forth guidelines for the diagnosis and treatment of IgG4-RD. In the case presented here, the patient initially presented with pain and weakness in the left upper extremity. Initial neuroimages revealed a contrast-enhancing mass extending from C-4 to T-1, invading the epidural spinal canal, encasing the exiting nerve roots, infiltrating the paraspinal musculature, and surrounding the left vertebral artery. A PET scan confirmed the mass was hypermetabolic, but results of fine-needle aspiration and CT-guided biopsy were inconclusive. Open biopsy yielded fibrotic tissue that met the pathological criteria for IgG4-RD: lymphoplasmacytic infiltrate, fibrosis in a storiform pattern, and obliterative phlebitis. The patient was treated with 2 doses of 4 mg of dexamethasone (Decadron) and then 50 mg of prednisone per day. Within 2 weeks, the mass was radiologically shown to have drastically decreased in size. The prednisone dose was decreased to 40 mg per day, and 100 mg of azathioprine per day was added. The patient continued to improve and the mass continued to decrease over the next 6 months. Currently, she has been weaned from all steroids and will be maintained on a daily dose of 100 mg of azathioprine.

IgG4-related retroperitoneal fibrosis: a newly characterized disease

Retroperitoneal fibrosis (RPF) is a rare disease characterized by chronic, nonspecific inflammatory and sclerotic or fibrotic tissue in the periaortic or periiliac retroperitoneum that encases adjacent structures. There will be a series of clinical manifestations once the proliferated fibrous tissues encase the abdominal aorta, iliac arteries and urinary duct. RPF is generally divided into two types: idiopathic retroperitoneal fibrosis (IRPF) without identified pathogenesis, making up about two-thirds of cases, and secondary retroperitoneal fibrosis. Recent studies on Immunoglobulin G4-related disease (IgG4-RD) reveal that abundant infiltration of IgG4 positive plasma cells is found in biopsies on the mass of RPF of some IRPF patients, which is identified as one spectrum of IgG4-RD and is named IgG4-related RPF. IgG4-related RPF is often misdiagnosed as retroperitoneal visceral malignancy and is treated with surgery. In addition, because of its good response to glucocorticoid, early detection and treatment is important. We review the definition, epidemiology, clinical features, diagnostic criteria, treatment and prognosis of IgG4-related RPF in this article to raise awareness of this newly characterized disease.

IgG4-related disease: current challenges and future prospects

Immunoglobulin G4-related disease (IgG4-RD) represents an immune-mediated fibroinflammatory condition with a characteristic histopathological appearance that can affect various organs. Although numerous single-organ manifestations have been described more than a century ago, its systemic nature and unique features were only discovered in the last 2 decades, when IgG4-RD emerged as a new entity of disease. IgG4-RD is usually considered a rare disease, but its true epidemiology has not yet been fully clarified. Also, despite recent advances in the identification of the underlying immunological processes, its pathophysiology is only incompletely understood till now. The diagnostic workup of IgG4-RD is complex and usually requires a combination of clinical examination, imaging, histological, and serological analyses. However, no finding alone is specific for IgG4-RD. Therefore, its diagnosis requires careful interpretation of examination results in context with the patient’s clinical appearance as well as the exclusion of a broad variety of differential diagnoses. The past years brought rapid advances concerning this novel disease entity: diagnostic criteria, further insights into the underlying immunological processes, new biomarkers, and novel therapeutic approaches were proposed and widened the knowledge in the field of IgG4-RD. Still, a greater number of questions remain unanswered, and many recent developments require further discussion and proof from clinical trials. This review should give an overview on current knowledge and future perspectives in epidemiology, pathophysiology, diagnosis, and therapy of IgG4-RD.

Overview of IgG4-Related Tubulointerstitial Nephritis and Its Mimickers

Tubulointerstitial nephritis (TIN) is the most common form of renal involvement in IgG4-related disease. It is characterized by a dominant infiltrate of IgG4-positive plasma cells in the interstitium and storiform fibrosis. Demonstration of IgG4-positive plasma cells is essential for diagnosis, but the number of IgG4-positive cells and the ratio of IgG4-positive/IgG-positive plasma cells may vary from case to case and depending on the methods of tissue sampling even in the same case. IgG4-positive plasma cells can be seen in TIN associated with systemic lupus erythematosus, Sjögren syndrome, or anti-neutrophil cytoplasmic antibody–associated vasculitis, which further add diagnostic confusion and difficulties. To have a more clear view of IgG4-TIN and to delineate differential points from other TIN with IgG4-positive plasma cell infiltrates, clinical and histological features of IgG4-TIN and its mimickers were reviewed. In the rear part, cases suggesting overlap of IgG4-TIN and its mimickers and glomerulonephritis associated with IgG4-TIN were briefly described.