The birthday of a new syndrome: IgG4-related diseases constitute a clinical entity. Autoimmun Rev. 2010;9:591-594. [PMID: 20457280 DOI: 10.1016/j.autrev.2010.05.003]

Coronary periarteritis and pericarditis are rare but distinct manifestations of heart involvement in IgG4-related disease: a retrospective cohort study

BACKGROUND

The heart can be involved in immunoglobulin (Ig)-G4-related disease (IgG4-RD). This study aimed to summarize the clinical features and efficacy of treatment for IgG4-RD patients with heart involvement.

METHODS

We conducted a retrospective study enrolling 42 IgG4-RD patients with heart involvement from the IgG4-RD cohorts of the Peking Union Medical College Hospital and Beijing An Zhen Hospital, from 2010 to 2022. Clinical, laboratory, radiological data were collected, and treatment responses to glucocorticoids and immunosuppressants were analyzed.

RESULTS

IgG4-related cardiac involvement is a rare part of the IgG4-RD spectrum. The incidences of coronary periarteritis and pericarditis were 1.2%(13/1075) and 3.1%(33/1075), respectively in our cohort. Valvular disease possibly related to IgG4-RD was detected in two patients. None of the patients with myocardial involvement were identified. The average age was 58.2 ± 12.8 years, with a male predominance (76.7%). Coronary artery CT revealed that mass-like and diffuse wall-thickening lesions were the most frequently observed type of coronary periarteritis. Pericarditis presented as pericardial effusion, localized thickening, calcification and mass. After treatment with glucocorticoid and immunosuppressants, all patients achieved a reduced IgG4-RD responder index score and achieved radiological remission. Two patients with coronary peri-arteritis experienced clinical relapses during the maintenance period.

CONCLUSIONS

Cardiac involvement in IgG4-RD is rare and easily overlooked since many patients are asymptomatic, and the diagnosis relies on imaging. Patients showed a satisfactory response to glucocorticoid based treatment.

Mikulicz's disease combined with IgG4-related hypophysitis: a case report

BACKGROUND

IgG4-related diseases are very uncommon, and its diagnosis and treatment are complicated as it encompasses multiple disciplines.

CASE PRESENTATION

A 77-year-old woman was admitted with a jaw mass and nausea and vomiting. Laboratory tests showed elevated serum IgG4, pituitary MRI suggested thickening of the pituitary stalk, and head and neck CT suggested orbital and mandibular masses. Patients with mandibular mass were diagnosed with Mikulicz's disease with IgG4-related hypophysitis. We found no other evidence of causing thickening of the pituitary stalk. She was given oral prednisolone 30 mg daily, and her nausea and vomiting improved significantly, and the mandibular and ocular masses decreased in size.

CONCLUSION

Mikulicz's disease combined with IgG4-related hypophysitis is a rare case of IgG4-RD in elderly women. IgG4-RD is one of the causes of head and neck exocrine gland mass and pituitary stalk thickening in the elderly.

IgG4-related disease: Case report and 6-year follow-up of an elusive diagnosis mimicking malignancy

Key Clinical Message

IgG4-related disease is a rare and emerging pathology, characterized by the appearance of pseudotumors. Due to the ability to mimic other pathologies, it is essential to consider it as a differential diagnosis in multisystemic processes. The diagnosis is challenging, requiring a multidisciplinary approach, to minimize the associated morbidity and mortality.

Abstract

IgG4-related disease (IgG4-RD) is a rare, emerging, systemic and chronic pathology, characterized by the appearance of pseudotumors resulting from tissue infiltration by IgG4-positive plasma cells that promote eosinophilic inflammation of the tissue with subsequent fibrosis. We present the case of a male, 45-year-old patient, with marked weight loss and skin pallor detected by his family doctor during a child health consultation of his daughter. When questioned, the patient referred complaints of postprandial discomfort in the left hypochondrium with a feeling of fullness, weight loss, chronic fatigue and hyperhidrosis that had lasted for a month. On physical examination, he was pale, and had pain at palpation of the left hypochondrium. Laboratory data showed increased inflammation markers, abdominal ultrasound and CT demonstrated numerous enlarged lymph nodes in the upper quadrants, raising concern for a malignant lymphoproliferative process. Serological, imaging, clinical and laparoscopic excisional biopsy revealed features of IgG4-related disease and excluded malignant lymphoproliferative disease. The immediate response to treatment with oral prednisolone 30 mg/day also contributed for diagnosis confirmation. Due to refractory disease after gradual prednisolone reduction, second-line therapy with rituximab was initiated. Over the 6 years of follow-up, the patient presented multiple exacerbations characterized by the emergence of systemic symptoms, being maintained under close clinical and imaging follow-up by reumathology, infectious diseases, and family medicine specialists.

Clinical patterns and risk factors for multiorgan involvement in IgG4-Related disease patients

Background

IgG4-related disease with multiorgan involvement predicts higher disease activity, thus, it is necessary to identify whether IgG4-related disease involves multiple organs at the early stage. To further clarify the clinical characteristics and risk factors for IgG4-related disease with multiorgan involvement, we conducted an observational study.

Methods

We retrospectively analysed the clinical data of 160 patients who were primarily diagnosed with IgG4-related disease at the First Affiliated Hospital of Zhengzhou University from January 2015 to January 2021. According to the number of involved organs, patients were divided into two groups: multiorgan involvement and nonmultiorgan involvement. Patients were divided into a multiorgan group and a nonmultiorgan group according to multiple organ involvement.

Results

There were 82 cases identified with multiorgan involvement and 78 cases diagnosed with no multiorgan involvement in this series. Most cases were elderly and male (p > 0.05). The most frequently affected organs in IgG4-RD were the lymph nodes (50.6 %), pancreas (38.7 %) and salivary glands (35.6 %). Multivariate analysis showed that eosinophilia, IgG4>2*ULN, lymph node involvement, salivary gland involvement and lung involvement were independent risk factors for multiorgan involvement (p < 0.05).

Conclusions

The main issues in clinical practice are how to accurately diagnose the disease and screen the more vulnerable organs.

Immunoglobulin G4-Related Disease of the Intestine: A Clinicopathological Entity to Be Considered

Background and Objectives: Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized immune-mediated, systemic condition of unknown etiology, associated with fibroinflammatory lesions. Diagnosis is set in the presence of IgG4-positive plasma cell infiltration of the involved tissue and elevated serum IgG4 levels. However, approximately 30% of patients have normal serum IgG4 levels. IgG4-RD may affect several organs, including the pancreas, bile ducts, mesentery, retroperitoneum, and salivary glands, but the involvement of the gastrointestinal tract is uncommon. Materials and Methods: The case series of 4 patients with IgG4-RD involving the intestinal tract was observed in the period of 2017-2022. Colorectal and ileal biopsy specimens were stained with hematoxylin and eosin and immunohistochemical techniques using monoclonal antihuman IgG4 primary antibody. Diagnosis of IgG4-RD was based on the presence of >50 cells/ HPF and IgG4/IgG ratio >40 confirmed by two pathologists. Results: IgG4-RD was set in patients previously diagnosed as affected by Crohn's disease. Conclusions: Systematic IgG4 immunohistochemical staining should be considered in the diagnostic workup of patients with gastrointestinal strictures, mimicking Crohn's disease. The exact prevalence of the condition is likely more frequent than reported and should be defined by a large series of consecutive patients.

Infrequent organ involvement in immunoglobulin G4-related prostate disease: A case report

BACKGROUND

Immunoglobulin G4-related prostate disease (IgG4-RPD) characterized by a high count of IgG4-positive plasma cells has distinctive serological and radiological findings. Here we report a case of a patient who was successfully treated for IgG4-RPD, which manifested as frequent micturition, dysuric, and systemic lymphadenopathy.

CASE SUMMARY

The patient was a 33-year-old man who was referred to our hospital because of urinary tract symptoms that had persisted for 4 years. A physical examination revealed systemic lymphadenopathy and blood tests showed hyperglobulinemia with an IgG level of 18.90 g/L and an IgG4 level of 18.40 g/L. Computed tomography (CT) revealed bilateral lacrimal gland, right parotid gland and prostatic enlargement. Based on these findings, IgG4-RD was suspected, and further pathological examination and follow-up results showed expected results. Finally, the patient was diagnosed with IgG4-RPD based on clinical symptoms, pathological examination, therapeutic effects, and follow-up results. He received 50 mg oral prednisolone (the dose was gradually reduced and a low dose was used for long-term maintenance) in combination with cyclophosphamide 1.0 g via an intravenous drip for 6 mo. One year after the treatment was initiated, he was free of urinary or other complaints and his serum IgG4 level normalized.

CONCLUSION

In IgG4-RPD with severe urinary tract symptoms, radiological findings should be carefully examined. IgG4-RPD prognosis is good because the disease responds well to glucocorticoids. Furthermore, it is urgent for clinicians and pathologists to improve their understanding of IgG4-RPD.

IgG4-related digestive diseases: diagnosis and treatment

IgG4-related digestive diseases encompass a group of chronic inflammatory disorders characterized by autoimmune reactions and fibrosis affecting multiple digestive organs. These diseases are identified by elevated serum levels of IgG4 and the presence of IgG4-positive plasma cell infiltration in the affected sites, along with storiform fibrosis, obliterative phlebitis, and eosinophilic infiltration. Although extensive research has been conducted, a comprehensive understanding of these conditions remains elusive. Current clinical diagnosis often relies on the application of integrated diagnostic criteria for IgG4-related diseases, combined with specific organ involvement criteria. Distinguishing them from malignancies poses considerable challenges. Moreover, further investigations are required to elucidate the underlying pathogenic mechanisms and explore potential therapeutic interventions. This review provides a systematic classification of IgG4-related digestive diseases while discussing their diagnostic strategies, clinical presentations, and treatment modalities. The comprehensive insights shared herein aim to guide clinicians in their practice and contribute to the advancement of knowledge in this field.

Single-Cell RNA-Sequencing Reveals Peripheral T Helper Cells Promoting the Development of IgG4-Related Disease by Enhancing B Cell Activation and Differentiation

Abnormal B cell differentiation plays a critical role in IgG4-related disease (IgG4-RD), but the underlying mechanism remains largely unknown. We investigated the cell landscape from three IgG4-RD retroperitoneal tissues and three control tissues using single-cell RNA-sequencing. Critical cell type or markers were further validated in the peripheral blood from the patients with IgG4-RD and healthy controls via flow cytometry as well as in the IgG4-RD and control tissue via immunofluorescence staining. The increases in B cells, plasma cells, and CD4+ T cells were found in IgG4-RD retroperitoneal tissue. Importantly, among CD4+ T cells, an increase in CD4+CXCR5-PD1hi peripheral T helper (Tph) cells with a high expression of IL-21 and TIGIT was discovered in IgG4-RD tissue, which was further validated in peripheral blood of the patients with IgG4-RD. The Tph cell and TIGIT+ Tph cell proportion were remarkably higher in active IgG4-RD patients and correlated with disease activity. Moreover, TIGIT+CD4+ cells were able to promote B cell differentiation via IL-21. Our study revealed that Tph cells are increased in IgG4-RD and probably play critical roles in B cell differentiation through TIGIT-IL-21 axis. Peripheral Tph cell and TIGIT+Tph cell are potential markers for IgG4-RD disease activity.

Epiduritis related to IgG4 disease: A very rare cause for spinal cord compression

Background

Inflammatory pseudotumors are rare, and those attributed to immunoglobulin G4 (IgG4) diseases are even less frequently encountered. Here, we reviewed 41 cases from the literature of spinal inflammatory pseudotumors due to IgG4 and have added our single new case.

Case Presentation

A 25-year-old male presented with progressive back pain, bilateral paraparesis, and sphincter dysfunction. His deficit was attributed to MR-documented posterolateral lesion between the T5 and T10 levels for which he levels underwent a T1-T1010 laminectomy. The pathology revealed an immunoglobulin G4-related inflammatory pseudotumor. Postoperatively, the patient additionally required systemic and epidural administration of glucocorticoids.

Conclusion

IgG4-related disease is an emerging clinical condition that rarely involves the central nervous system. Spinal inflammatory pseudotumors, including IgG4 disease, should be more commonly considered among the potential differential diagnoses of lesions compressing the spinal cord.

IgG4-related disease with kidney and lymph nodes involvement: a case-based review

IgG4-related disease (IgG4-RD), a rare immune-mediated chronic fibro-inflammatory condition, has various initial symptoms, thus posing diagnostic and therapeutic challenges. Here, we report a case of IgG4-RD in a 35-year-old man with initial clinical symptoms of facial edema and recent onset of proteinuria. It took more than 1 year from the onset of clinical symptoms to diagnosis. Pathological examination of renal biopsy revealed significant renal interstitial lymphoid tissue hyperplasia simulating growth pattern of lymphoma. Immunohistochemical (IHC) staining results showed that CD4 + T lymphocyte hyperplasia was dominant. There was no significant deletion of CD2/CD3/CD5/CD7. No monoclone was detected in TCR gene rearrangement. IHC staining showed that the number of IgG4-positive cells was greater than 100/HPF. The ratio of IgG4/IgG was greater than 40%. Combined with clinically examinations, IgG4-related tubulointerstitial nephritis was considered. Further cervical lymph node biopsy results suggested IgG4-related lymphadenopathy. He received methylprednisolone 40 mg/day intravenously for 10 days, leading to normal results of laboratory tests and clinical manifestations. The patient had a good prognosis without recurrence during 14 months of follow-up. This case report can be used as a reference for early diagnosis and treatment of such patients in the future.

IgG4-related kidney disease complicated with retroperitoneal fibrosis: A case report

BACKGROUND

IgG4-related disease (IgG4-RD) is a chronic fibrotic disease mediated by immunity recognized by clinicians in recent years. When the kidney is involved, it is called IgG4-related kidney disease (IgG4-RKD). IgG4-related tubulointerstitial nephritis (IgG4-TIN) is a representative manifestation of IgG4-RKD. IgG4-TIN can cause obstructive nephropathy complicated by retroperitoneal fibrosis (RPF). Cases of IgG4-TIN complicated with RPF are rare. Glucocorticoids are the first-line therapeutic medication for IgG4-RD and can significantly improve renal function.

CASE SUMMARY

Herein, we report the case of a 56-year-old man with IgG4-RKD complicated with RPF. The patient presented to the hospital with complaints of elevated serum creatinine (Cr), nausea, and vomiting. During hospitalization, Cr was 1448.6 µmol/L, and serum IgG4 was increased. A total abdominal computed tomography (CT) scan and enhanced CT scan obviously indicated RPF. Although this patient had a long course and renal insufficiency, we performed a kidney biopsy. Renal biopsy showed that the renal tubulointerstitium had focal plasma cell infiltration and increased lymphocyte infiltration accompanied by fibrosis. After combining the biopsy results with immunohistochemistry, it was found that the absolute number of positive IgG4+ cells per high power field exceeded 10, and the ratio of IgG4/IgG was over 40%. Finally, the patient was diagnosed with IgG4-TIN complicated with RPF and given glucocorticoids as long-term maintenance therapy, helping him keep out of dialysis. After a follow-up of 19 mo, the patient had recovered well. Previous literature on IgG4-RKD and RPF was retrieved from PubMed to characterize the clinical and pathological features and to identify the diagnosis and treatment of IgG4-RKD.

CONCLUSION

Our case report demonstrates the clinical characteristics of IgG4-RKD complicated with RPF. Serum IgG4 is a favorable indicator for screening. Performing renal biopsy actively plays a vital role in diagnosis and treatment, even if the patient has a long course and manifests with renal insufficiency. It is remarkable to treat IgG4-RKD with glucocorticoids. Hence, early diagnosis and targeted therapy are essential for reversing renal function and improving extrarenal manifestations in patients with IgG4-RKD.

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.

IgG4-related hypophysitis: A monocentric experience from North India

Background

Immunoglobulin (Ig)G4-related disease is a systemic fibroinflammatory disease characterized by dense infiltration of IgG4-positive plasma cells in the affected tissue(s) with or without elevated plasma levels of IgG4. Hypophysitis itself is a very rare disease with reported prevalence in the operative specimens are around 0.2-0.88%. IgG4-related hypophysitis (IgG4-RH) may account for a substantial percentage of cases previously regarded as idiopathic hypophysitis.

Methods

This study is a registry-based, retrospective, and cohort study from a tertiary care hospital in North India. The medical records and clinical data of biopsy-proven and suspected IgG4-RH patients registered were retrospectively analyzed. Treatment outcome of cases was also explored during this analysis.

Results

Two thousand and six sellar area space-occupying lesions have been operated-on since 2006, among them only four patients had IgG4-RH on histopathological specimen. One case was diagnosed on clinical suspicion. Mean age of the patients was 31.8 ± 6.32 years. Most frequent presenting complaint was headaches. Extracranial manifestations were present in four patients. The most common pituitary dysfunction was cortisol deficiency. 18 F-fluorodeoxyglucose positron emission tomography (18F FDG PET) was helpful in three cases for diagnosis of hypophysitis and other organ involvement. Classical histological findings with storiform fibrosis, obliterative phlebitis seen in two cases, and IgG4-positive plasma cell infiltration were positive in four cases. Surgery was the primary modality of treatment in all four cases. Only one patient received steroids as a primary therapeutic modality.

Conclusion

IgG4-RH is rare. High index of suspicion is required to diagnosis the case precisely. FDG PET is helpful in diagnosing hypophysitis and extrapituitary lesions.

IgG4-related disease diagnosed in a paratesticular pseudotumor simulating malignancy, in a patient with retroperitoneal fibrosis

IgG4 related disease is a term used to describe a fibroinflammatory condition characterized by storiform fibrosis, inflammation with a dense lymphoplasmocytic infiltrate rich in plasma cells expressing IgG4, and often, if not always, raised serum levels of IgG4. We report a case of a patient with a past history of retroperitoneal fibrosis presenting with a swollen left testicle, who underwent an orchidectomy due to suspicion of malignancy. The surgical specimen revealed a paratesticular pseudotumor with histopathological and immunohistochemical characteristics of IgG4 related disease. To the best of our knowledge, just nine such cases have previously been reported, of which only three were manifestations of systemic disease, as in the present case. Whilst it is important to recognize the clinical and radiological features of this entity, histopathology is often essential in order to confirm the diagnosis.

Management of retroperitoneal fibrosis with endovascular aneurysm repair in patients refractory to medical management

Background

Early diagnosis and treatment of under-recognized retroperitoneal fibrosis (RPF) are essential before reaching the poorly responsive fibrotic stage. Although most patients respond to medical therapy, relapses and unresponsiveness are common. However, open surgery in medically resistant patients is associated with major adverse clinical events.

Methods

This is a single-centre longitudinal study of optimal medical therapy (OMT) vs. endovascular aneurysm repair (EVAR) in patients presenting with RPF to our tertiary referral vascular centre. Out of 22,349 aortic referrals, we performed 1,555 aortic interventions over twenty years. Amongst them, 1,006 were EVAR, TEVAR and BEVAR. Seventeen patients (1.09%) had documented peri-aortic RPF.

Results

Out of the 17 RPF patients, 11 received OMT only, while 6 underwent EVAR after the failure of OMT. 82% (n = 14) were male, and the median follow-up was 62.7 months (IQR: 28.2–106). Nine (52%) had immunoglobulin G4-related disease (4 OMT vs. 5 EVAR). EVAR patients had 100% technical success without perioperative mortality. Furthermore, all the EVAR patients were symptom-free following the intervention. Pre-operative aortic RPF index (maximum peri-aortic soft tissue diameter/maximum aortic diameter) was higher in the EVAR than in OMT. However, there was a significant decrement in the aortic RPF index following EVAR (P = 0.04).

Conclusion

We believe that when optimal medical therapy fails in RPF, EVAR provides a promising outcome. Further studies are recommended to establish the role of endovascular repair.

Clivus-involved immunoglobulin G4 related hypertrophic pachymeningitis mimicking meningioma: A case report

BACKGROUND

Immunoglobulin G4 related disease (IgG4-RD) is a fibroinflammatory disease with markedly elevated serum IgG4 levels and fibrous tissue proliferation, accompanied by numerous plasma cells. IgG4 related hypertrophic pachymeningitis (IgG4-RHP) is relatively rare and indistinguishable from other phymatoid diseases before the operation. The risk of long-term immunosuppression needs to be balanced with disease activity.

CASE SUMMARY

A 40-year-old man presented with headache and bilateral abducent paralysis. He was also diagnosed with pulmonary tuberculosis 10 years ago and was on regular treatment for the same. Before the operation and steroid therapy, the patient was suspected of having tubercular meningitis at a local hospital. A clivus lesion was found via brain magnetic resonance imaging (MRI) at this presentation. He was preliminarily diagnosed with meningioma and underwent Gamma Knife Surgery. Transnasal endoscopic resection was performed to treat deterioration of nerve function. Postoperative pathologic examination suggested IgG4-RD. Moreover, the serum IgG4 was elevated at 1.90 g/L (reference range: 0.035-1.500 g/L). After steroid therapy for 2 mo, the lesion size diminished on MRI, and the function of bilateral abducent nerves recovered.

CONCLUSION

IgG4-RHP is relatively rare and indistinguishable before the operation. Elevated serum IgG4 levels and imaging examination help in the diagnosis of IgG4-RHP. Surgery is necessary when lesions progress and patients start to develop cranial nerve function deficit.

Immunoglobulin G4-related kidney disease involving the renal pelvis and perirenal fat: A case report

BACKGROUND

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is an autoimmune disease associated with chronic and progressive inflammation and fibrosis. It is difficult to differentiate IgG4-RD involving the kidney from infectious diseases and malignancy on imaging.

CASE SUMMARY

We report the case of a 51-year-old Chinese man whose abdominal computed tomography scan showed diffuse bilateral enlargement of the kidneys and perirenal fat, thickening of the renal pelvic walls, and hydronephrosis of the right kidney. Relevant laboratory test results showed a serum creatinine level of 464 μmol/L. The patient was diagnosed with acute renal failure and was started on intermittent hemodialysis. Further tests revealed high serum IgG4 levels (20.8 g/L) and an enlarged right submaxillary lymph node. Biopsy and histopathological examination of the enlarged node led to the diagnosis of IgG4-RD. After corticosteroid therapy, his serum creatinine level quickly decreased to near normal levels.

CONCLUSION

IgG4-RD affecting the renal pelvis or perirenal fat is rare, with atypical imaging features. Multidisciplinary consultation is critical for accurate diagnosis and treatment of this disease. Suspected cases should undergo biopsy to avoid misdiagnosis.

IgG4-related mastitis requiring differentiation from breast cancer: a case report

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a group of chronic relapsing inflammatory conditions. Although IgG4-RD can occur in various organs, it is rarely observed in mammary glands. Here, we report a case of IgG4-related mastitis (IgG4-RM) that needed to be differentiated from breast cancer. A 54-year-old woman was examined for a tumor in her left breast. Mammary ultrasonography revealed an irregular hypoechoic tumor measuring 45.0 × 43.0 × 32.0 mm in size. A core-needle biopsy of the left breast tissue revealed a high degree of mixed T and B lymphocytic and plasma cell infiltration, as well as interstitial fibrosis. IgG4-RD was diagnosed based on hematological examination that revealed an abnormal IgG4 value of 332 mg/dl. All the clinical diagnostic criteria for IgG4 were met, resulting in a definitive diagnosis of IgG4-RM.

Immune Dysregulation in IgG4-Related Disease

Immunoglobin G₄-related disease (IgG₄-RD) is one of the newly discovered autoimmune diseases characterized by elevated serum IgG₄ concentrations and multi-organ fibrosis. Despite considerable research and recent advances in the identification of underlying immunological processes, the etiology of this disease is still not clear. Adaptive immune cells, including different types of T and B cells, and cytokines secreted by these cells play a vital role in the pathogenesis of IgG₄-RD. Antigen-presenting cells are stimulated by pathogens and, thus, contribute to the activation of naïve T cells and differentiation of different T cell subtypes, including helper T cells (Th1 and Th2), regulatory T cells, and T follicular helper cells. B cells are activated and transformed to plasma cells by T cell-secreted cytokines. Moreover, macrophages, and some important factors (TGF-β, etc.) promote target organ fibrosis. Understanding the role of these cells and cytokines implicated in the pathogenesis of IgG₄-RD will aid in developing strategies for future disease treatment and drug development. Here, we review the most recent insights on IgG₄-RD, focusing on immune dysregulation involved in the pathogenesis of this autoimmune condition.

IgG4-Related Disease Manifesting as Hypocomplementemic Tubulointerstitial Nephritis: A Rare Case Report and Literature Review

Immunoglobulin G4–related disease (IgG4-RD) is a chronic fibrosing inflammatory systemic disorder that has been recognized relatively recently in the medical literature. Little is known about the exact disease pathogenesis and epidemiology. IgG4-RD may be asymptomatic or may have minimal symptoms or involve multiple organs with overt symptoms. The different phenotypes of IgG4-RD can lead to delayed or incorrect diagnosis. We report the case of a 66-year-old male with coal worker’s pneumoconiosis who presented with progressive kidney disease and was diagnosed with tubulointerstitial nephritis due to IgG4-RD. The patient was noted to have progressive kidney disease, skin involvement, worsening interstitial lung disease, complete vision loss in the left eye, and retroperitoneal fibrosis. Serologic workup revealed elevated inflammatory markers, IgG4 and IgG1 levels, and hypocomplementemia. A tissue biopsy helped us establish a definitive diagnosis of IgG4-RD and initiate treatment with glucocorticoids to prevent further progression of kidney disease and other end-organ damage.

Inflammatory pseudotumor of Castleman disease and IgG4-related disease masquerading as kidney malignancy

Background

With widespread clinical application of imaging techniques, renal space-occupying lesions have been identified at an increasing frequency. Here, we report two rare cases, Castleman disease (CD) and IgG4-related disease (IgG4-RD), presenting primarily with the symptoms and imaging findings of kidney malignancy.

Case presentation

In case 1, an occupying lesion located in the right renal pelvis was detected using magnetic resonance imaging in a 32-year-old female who presented with hematuria and lumbago. First misdiagnosed as carcinoma of the renal pelvis, the patient underwent right radical nephroureterectomy. However, postoperative pathological and immunohistochemistry studies finally confirmed the diagnosis of CD. In case 2, a 45-year-old male presented with the chief complaint of anuria. Nephrostomy and renal biopsy indicated lymphoma, following which, antegrade urography and computed tomography urography were performed, which revealed bilateral hydronephrosis and mass lesions around the renal pelvis. Partial resection of the masses and frozen section examination indicated the diagnosis of CD. However, the results of postoperative histopathology and immunohistochemistry combined with serum IgG4 were consistent with IgG4-RD. Both the patients recovered well after drug treatment without recurrence of the diseases.

Conclusions

Inflammatory pseudotumor of CD and IgG4-RD with kidney involvement are primarily diagnosed by postoperative histopathology and can pose a preoperative diagnostic challenge because these lesions can masquerade as kidney malignancy. Therefore, we recommend core biopsy as a nonnegligible procedure to evaluate renal masses and potentially prevent unnecessary surgical treatment.

Establishment of time-resolved fluoroimmunoassay of IgG4 based on magnetic microspheres

BACKGROUND

The abnormal increase in serum IgG4 level is an important clinical symptom of IgG4-related disease (IgG4-RD), and the detection of serum IgG4 level is a powerful tool for the diagnosis of IgG4-RD. This study was conducted to establish a simple and rapid immunoassay for the determination of human serum IgG4 levels.

METHODS

Based on the competition method, a novel immunoassay was established for the determination of human serum IgG4 using a combination of time-resolved fluoroimmunoassay (TRFIA) and magnetic microspheres. IgG4 was coupled with magnetic microspheres and competed with IgG4 in the samples to bind the Eu3+ -labeled anti-IgG4 antibody. The immunocomplex was separated and washed in a magnetic field, and the fluorescence counts were measured according to the number of dissociated europium ions.

RESULTS

The analytical sensitivity of IgG4-TRFIA based on magnetic microspheres was 0.006 g/L, and the detection range was 0.006-20 g/L under optimal conditions. The precision, recovery, and specificity of this immunoassay were demonstrated to be acceptable. The clinical application of IgG4-TRFIA based on magnetic microspheres was evaluated and compared with that of immunonephelometry. The results showed that the two detection methods had a good correlation, with a correlation coefficient of .9871.

CONCLUSION

IgG4-TRFIA based on magnetic microspheres has the advantages of high sensitivity, wide detection range, and short analysis time and has the potential to become a useful tool for the diagnosis of IgG4-RD.

Improved clinical outcomes of tocilizumab versus cyclophosphamide for IgG4-related disease: insights from a prospective IgG4-related disease registry

Objective

To compare the clinical outcomes of patients with active immunoglobulin G (IgG) 4 related disease (IgG4-RD) receiving tocilizumab versus those receiving cyclophosphamide (CYC).

Methods

This IgG4-RD registry study was a prospective cohort study conducted among patients with active IgG4-RD hospitalized at Zhongshan Hospital, Fudan University. Patients who were treated with tocilizumab or CYC along with glucocorticoids (GCs) were enrolled. All participants were followed up at the hospital clinic at 3 and 6 months after discharge. Primary clinical outcomes were measured via the IgG4-RD responder index (RI), complete response (CR), and partial response (PR), as well as side effects.

Results

From January 2015 to June 2020, 29 patients enrolled. Fourteen and 15 patients were treated with tocilizumab and CYC, respectively. At the 6-month follow-up, disease activity parameters including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), IgG4, and IgG4-RD RI, decreased significantly in both groups. At 6 months, tocilizumab demonstrated its superiority, with 50% of patients achieving CR in the Tocilizumab group versus 20% in the CYC group. However, no statistical significance was identified (p = 0.128). The GC dosage at 6 months was significantly lower in the tocilizumab group than in the CYC group [10 (9.4-15) mg/d versus 15 (15-15) mg/d, p = 0.025]. In the CYC group, two patients experienced lumbar vertebral compression fractures related to GCs. Other patients in both groups showed mild adverse effects.

Conclusions

Tocilizumab could be a better steroid-sparing agent, with a comparable curative effect and tolerance, than CYC, in the treatment of IgG4-RD.

Atypical presentation of immunoglobulin G4-related disease as subglottic stenosis: a case-based review

Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized fibro-inflammatory pathology that has been reported to affect principally the retroperitoneum, hepatobiliary system, salivary glands, orbital structures or lymph nodes. However, IgG4-RD with laryngeal involvement is a very rare entity. Our aims were to describe a case of subglottic stenosis as first and only manifestation of IgG4-RD and review the literature. A patient with IgG4-RD affecting the larynx that presented as subglottic stenosis is described. A MEDLINE database search of IgG4-RD cases with laryngopharyngeal manifestations was also conducted. A 30-year-old Caucasian woman was referred to a tertiary care hospital for dyspnea on exertion, which had been increasing for the last 4 months. Medical and surgical procedures revealed a subglottic stenosis, with a histological finding of IgG4 positive plasma cell infiltration. There was no evidence of other organ involvement. She was successfully treated with oral glucocorticoids and rituximab infusions. Glucocorticoids were rapidly tapered and the rituximab regimen was optimized, with no evidence of relapses. In the literature review, we found a total of 12 reported cases with laryngopharyngeal involvement, two of them with subglottic stenosis. IgG4-RD of the larynx is rare but should be considered after excluding more common disorders.

Localized IgG4-related disease manifested on the tongue: a case report

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition that can affect multiple organs. IgG4-RD may show a variety of initial symptoms. In the oral mucosa, lesions present as inflammatory fibrosis with a large number of IgG4-positive plasma cells. Evaluating treatment is a well-known problem in IgG4-RD due to the absence of an established assessment system. There are difficulties in defining the severity of the disease, which is why treatment is primarily based on its clinical manifestations. We present a case report of localized IgG4-RD with ulcerative and proliferative manifestations on the tongue, which clinically mimicked oral squamous cell carcinoma. A tumor-like lesion on the tongue can indicate something else other than the malignant or reactive changes commonly found in the oral mucosa. Multiple differential diagnoses of these atypical oral lesions, including localized IgG4-RD, should be considered.

Prognostic factors in IgG4-related disease: a long-term monocentric Chinese cohort study

OBJECTIVES

Patients with IgG4-related disease (IgG4-RD) suffer high relapse rates during long-term treatment, but factors that predict relapse outcomes are not well established. In the present study, we aimed to identify predictive factors for treatment resistance and disease relapse in a Chinese IgG4-RD cohort.

METHODS

This study enrolled 102 patients newly diagnosed with IgG4-RD. Disease prognosis was determined by evaluating disease activity and dosage of glucocorticoids. Predictive factors for refractory and relapsed disease were identified by univariate analysis and Cox regression.

RESULTS

Among the 102 patients, 78 cases received medical treatment with regular follow-up (21 [6-111] months). During the follow-up period, 55 (70.5%) patients sustained clinical remission, and 23 (29.5%) patients suffered refractory or relapsed disease. The relapse rate of the patients with IgG4-RD was significantly higher among patients who stopped taking medicine than among those who continued treatment with glucocorticoids (GC) + immunosuppressor (IM). Serum TNF-α ≥ 13 pg/mL, sIL-2R ≥ 1010 U/mL, total cholesterol < 3.55 mmol/L, low-density lipoprotein < 2.0 mmol/L, IgG ≥ 20.2 g/L, and drug withdrawal were predictive factors for refractory and relapsed IgG4-RD. Multivariate Cox regression revealed that both sIL-2R and TNF-α were independent risk factors for refractory and relapsed disease. The combination of GC and IM treatment was an independent protective factor against refractory and relapsed IgG4-RD.

CONCLUSIONS

High serum levels of sIL-2R and TNF-α may be informative risk factors for refractory and relapsed IgG4-RD. Our data suggest that a combination treatment of GC along with IM may be protective against refractory and relapsed IgG4-RD. Key Points • High sIL-2R and TNF-α levels are informative risk factors for refractory and relapsed IgG4-related disease. • Combination treatment of GC with IM protects against refractory and relapsed IgG4-related disease.

Idiopathic membranous nephropathy in a patient diagnosed with IgG4-related disease: A case report

RATIONALE

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a newly recognized, systemic disease. Membranous nephropathy is the most common glomerular lesion in IgG4- related kidney disease. However, the lack of relationship with IgG4-related kidney disease and monoclonal gammopathy of undetermined significance (MGUS) warrants investigation of the potential mechanisms.

PATIENT CONCERNS

A 62-year-old patient was diagnosed with IgG4-RD, tubulointerstitial nephritis, retroperitoneal fibrosis. After 2 years, she was presented with proteinuria, hypoproteinemia, facial, and bilateral lower limb edema. Furthermore, this patient exhibited deposits of IgG k of monoclonal hyperplasia, and bone marrow plasma cell count was 2.5%.

DIAGNOSIS

The patient was diagnosed with nephrotic syndrome, acute kidney injury, and MGUS. The pathological diagnosis was IgG4-related tubulointerstitial nephritis, IgG4-related membranous nephropathy.

INTERVENTIONS

The patient was treated with intravenous methylprednisolone (40 mg daily), which was changed to oral prednisone 50 mg/d after 2 months.

OUTCOMES

After 1 month, the patient exhibited a rapid response only with corticosteroid, and experienced partial remission of serum albumin and proteinuria.

LESSONS

This case may suggest a possible relationship between IgG4-RD and MGUS, provide some guidance for investigating the mechanism between them.

A rare case report of immunoglobulin G4-related sclerosing mesenteritis and review of the literature

INTRODUCTION

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a rare autoimmune disorder involving 1 or multiple organs, most commonly the pancreas, lacrimal glands, and salivary glands. However, IgG4-related sclerosing mesenteritis (SM) involving the small-bowel mesentery is rare. Given that IgG4-related SM usually mimics the imaging characteristics of mesenteric malignancies, its preoperative diagnosis remains challenging. In addition, no specific consensus has been reached regarding the treatment of IgG4-related SM. Therefore, a better understanding of the characteristics, treatment, and prognosis of IgG-related SM is urgently needed. Herein, we report a rare case of IgG-related SM.

PATIENT CONCERNS

A 67-year-old man was admitted to our hospital after incidental detection of an abdominal mass on ultrasound imaging, although he reported being generally well. The findings on triple-phase abdominal computed tomography were highly consistent with a malignant mesenteric tumor.

DIAGNOSES

The hallmark histopathological features along with elevated levels of IgG4 (145 mg/dL) and imaging findings were indicative of IgG-related SM.

INTERVENTIONS

The patient was treated surgically. Postoperative histopathological examinations exhibited tissue infiltration with lymphocytes and IgG4-positive plasma cells, as well as fibrosis.

OUTCOMES

Ten days after surgery, the patient was discharged from the hospital, and did not show any clinical sign of IgG-related SM within 1-year follow-up.

CONCLUSION

This case highlights the mesentery as an uncommon site of involvement as well as how early IgG-related SM can be completely asymptomatic. Thus, this study has advanced our knowledge of IgG-related SM and may improve treatments for similar conditions.

A challenging case report of IgG4-related systemic disease involving the heart and retroperitoneum with a literature review of similar heart lesions

The IgG4-related disease is a distinct, steroid-responsive fibro-inflammatory disorder of unknown etiology. This multiorgan disease is characterized by tumefactive lesions that contain rich infiltrations of IgG4-positive plasma cells, with the pancreas, and the salivary and lacrimal glands being the main involved. The more common cardiovascular involvements include inflammatory peri-aortitis, coronary arteritis, and pericarditis. Intra-cardiac tumefactive lesions are rarely reported. Herein, we describe a challenging case of IgG4-related disease with a long-time lag between initiation of symptoms to proper diagnosis with biopsy-proven cardiac and retroperitoneal and possible pituitary gland involvement. Concerning the rarity of the cardiac lesion in our case, we conducted a literature review of similar case reports.

A Case With IgG4-Related Spinal Pachymeningitis Causing Spinal Cord Compression

Immunoglobulin G4 (IgG4)-related disease is a systemic disease characterized by sclerosing lesions and an increased serum IgG4 level. This condition can involve any organ, but IgG4-related spinal pachymeningitis is relatively rare. In the current study, we report a case of spinal cord compression caused by IgG4-related spinal pachymeningitis. A 39-year-old man presented to us with a 15-day history of back pain and a 3-day history of dysuresia, exacerbated by weakness in the lower extremities for 2 days. Cervical magnetic resonance imaging (MRI) showed strip-shaped abnormal signals along the anterior and posterior borders of the spinal cord at the C5–T4 levels. The IgG level in cerebrospinal fluid was 718.0 mg/L. Thoracic MRI revealed strip-shaped abnormal signals with remarkable enhancement along the anterior and posterior borders of the dural sac at the T1–T6 levels. Histopathological examination confirmed IgG4-related spinal pachymeningitis. The symptoms worsened rapidly, and surgical resection of the space-occupying lesion in the vertebral canal was performed for spinal decompression. Corticosteroid therapy was administered, and the patient's motor functions were mildly improved. IgG4-related disease can manifest as spinal pachymeningitis and cause spinal cord compression. Clinicians should be aware of this rare condition, and early diagnosis, timely surgical decompression, and appropriate corticosteroid therapy should be highlighted.

In vitro IL-6/IL-6R Trans-Signaling in Fibroblasts Releases Cytokines That May Be Linked to the Pathogenesis of IgG4-Related Disease

Background: The remarkable mechanisms of storiform fibrosis and the formation of high levels of IgG4 with a pathogenic germinal center (GC) in the inflammatory tissue of IgG4-RD remains unknown and may be responsible for the unsatisfactory therapeutic effect on IgG4-related diseases when using conventional therapy.

Objectives: To investigate the mechanisms of interleukin 6 (IL-6) inducing fibroblasts to produce cytokines for pathogenic GC formation in the development of IgG4-related disease (IgG4-RD).

Methods: The clinical data and laboratory examinations of 56 patients with IgG4-RD were collected. IL-6 and IL-6R expression in the serum and tissues of patients with IgG4-RD and healthy controls were detected by ELISA, immunohistochemistry, and immunofluorescence. Human aorta adventitial fibroblasts (AAFs) were cultured and stimulated with IL-6/IL-6 receptor (IL-6R). The effect of IL-6/IL-6R on AAFs was determined by Luminex assays.

Results: The serum IL-6 and IL-6R levels were elevated in active IgG4-RD patients and IL-6 was positively correlated with the disease activity (e.g., erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], and IgG4-RD responder index). IL-6 and IL-6R expression in the tissue lesions of IgG4-related retroperitoneal fibrosis and IgG4-related sialadenitis patients were also significantly higher than that in the normal tissues. In addition, there is a relative abundance of myofibroblasts as well as IgG4⁺ plasma cells in the tissues of IgG4-related retroperitoneal fibrosis. α-SMA and B cell differentiation cytokines (i.e., B cell activating factor), and α-SMA and T follicular helper (Tfh) cell differentiation cytokines (e.g., IL-7, IL-12, and IL-23) were co-expressed in the local lesions. In vitro, IL-6/IL-6R significantly promoted the production of B cell activating factor, IL-7, IL-12, and IL-23 in AAFs in a dose-dependent manner. This effect was partially blocked by JAK1, JAK2, STAT3, and Akt inhibitors, respectively.

Conclusions:In vitro IL-6/IL-6R trans-signaling in fibroblasts releases Tfh and B cell differentiation factors partially via the JAK2/STAT3, JAK1/STAT3, and JAK2/Akt pathways, which may be linked to the pathogenesis of IgG4-RD. This indicated that IL-6 and fibroblasts may be responsible for GC formation and fibrosis in the development of IgG4-RD. Blocking IL-6 with JAK1/2 inhibitors or inhibiting fibroblast proliferation might be beneficial for IgG4-RD treatment.

Urinary System Manifestation of IgG4-Related Disease: Clinical, Laboratory, Radiological, and Pathological Spectra of a Chinese Single-Centre Study

Background

IgG4-related disease is a new disease entity, but little attention was drawn to urinary system involvement besides nephritis or nephropathy. Here, we described clinical, radiological, and pathological manifestations of IgG4-related urinary disease (IgG4-RUD) and assess its treatment responses.

Methods

We conducted a retrospective study enrolling 65 IgG4-RUD patients from an IgG4-related disease (IgG4-RD) cohort of the Peking Union Medical College Hospital. Clinical, laboratory, radiological, pathological data were collected, and treatment response to immunosuppressants were analysed.

Results

IgG4-related interstitial nephritis (TIN, 32.3%), glomerular nephritis (GN, 7.7%), renal pelvis and ureter involvement (21.5%), abnormal radiology with quiescent clinical presentation (13.8%), and renal parenchymal lesion plus retroperitoneal fibrosis (RPF, 18.5%) were major lesion types of IgG4-RUD. All patients had elevated serum IgG4, 76.9% had hyperglobulinemia, and 92.3% had elevated serum IgE at diagnosis. IgG4-TIN patients presented with renal dysfunction, and 94.3% had low serum complement C3 and IgG4-GN presented with nephrotic syndrome, while renal pelvis and ureter involvement had normal renal function and urinalysis. IgG4-RPF with renal parenchymal involvement presented with acute renal dysfunction and required emergency medical intervention. Renal cortex low-density areas, parenchyma or pelvis nodular mass, bilateral enlargement of the kidney, and renal pelvis and ureter mass/wall thickening were specific image patterns of IgG4-RUD. Infiltration of plasma lymphocytes and storiform fibrosis were histopathological features of IgG4-RUD. Patients showed satisfactory responses to immunosuppressive treatment, but complete recovery of renal function was difficult to achieve in IgG4-TIN. Four patients (6.2%) experienced clinical relapses during the maintenance period.

Conclusion

IgG4-RUD had diverse lesion types and distinctive manifestations. Radiological examinations were helpful for diagnosis and treatment evaluation. Patients showed good initial response to immunosuppressive treatment but relapses could occur at the maintenance period.

IgG4-related disease mimicking renal pelvis tumor with peritoneal carcinomatosis

IgG4-RD may rarely present as a retroperitoneal fibrosis, mimicking carcinomatosis. Clinicians should consider this disease when encountering an idiopathic peritoneal and retroperitoneal fibrosis with renal involvement and hydronephrosis.

Immunological Role of IgG Subclasses

The loss of tolerance to self-antigens is the unequivocal "red line" of autoimmunity: both development of autoreactive T and B cells and production of polyclonal autoantibodies represent seminal keys to the pathogenesis of protean autoimmune diseases. Most of these autoantibodies are immunoglobulins G (IgG), functionally distinguished in four subclasses named IgG1, IgG2, IgG3, and IgG4, due to structural differences in the hinge and heavy chain constant regions. Different studies analyzed serum levels of IgG subclasses in the course of different disorders, showing that they might have a pathogenic role by regulating interactions among immunoglobulins, Fc-gamma receptors, and complement. To date, the mechanisms promoting different IgG subclasses distribution during the natural history of most autoimmune diseases remain somewhat unclear. Evidence from the medical literature shows that the serum IgG profile is peculiar for many autoimmune diseases, suggesting that different subclasses could be specific for the underlying driving autoantigens. A better knowledge of IgG subsets may probably help to elucidate their pathological task, but also to define their relevance for diagnostic purposes, patients' personalized management, and prognosis assessment.

IgG4-related Retroperitoneal Fibrosis: An Emerging Masquerader With a Sinister Presentation

OBJECTIVE

Retroperitoneal fibrosis (RPF) is a rare proliferative fibro-inflammatory disease involving the soft tissues of the retroperitoneum. IgG4 related retroperitoneal fibrosis is an emerging entity which needs to be distinguished from idiopathic RPF. We describe a clinical case of IgG4 related RPF highlighting the importance of clinching this diagnosis.

METHODS

A 70 year old female was referred to the outpatient department of our institute with complaints of fatigue, bilateral flank pain and loss of appetite for the past 1 month. The CT and PET scan demonstrated a uniformly enhancing bulky retroperitoneal mass causing bilateral hydroureteronephrosis. The biopsy from the mass lesion revealed IgG4 related disease. The patient was started on corticosteroids after percutaneous nephrostomy placement.

RESULTS

Three months post induction of therapy, repeat PET-CT shows resolution of the mass with no FDG avid lesion. Serum IgG4 levels were reduced to normal (27 mg/dL) suggestive of response to treatment. The percutaneous nephrostomies were removed and the patient is doing well on maintenance dose of corticosteroids for her disease.

CONCLUSION

The availability of serum IgG4 levels for monitoring treatment response and follow-up can curtail the repeated radiological imaging and associated contrast exposure as compared to idiopathic RPF. Secondly, the diagnosis of IgG4-related RPF shall alert the clinician to look out for extra-retroperitoneal diseases on follow up of this multi-organ disease.

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

OBJECTIVE

To identify clinical and pathological differences between IgG4-related retroperitoneal fibrosis (IgG4-RPF) and idiopathic RPF (iRPF) in a Chinese population.

METHOD

Clinical and pathological data of 50 RPF patients from 2006 to 2016 were retrospectively analysed. The presence of at least one characteristic histopathological feature, >30 IgG4+ plasma cells per high power field, and an IgG4+/IgG+ plasma cells ratio cutoff of >40% were used to define IgG4-RPF.

RESULTS

Patients with IgG4-RPF were significantly more likely to have pain (94.1 vs 68.8%, P = 0.048), elevated serum IgE concentration (166.1 vs 40.2 IU/ml, P = 0.029) and tissue eosinophilia (47.1 vs 12.5%, P = 0.018), compared with patients with iRPF. In the IgG4-RPF subgroup, patients with tissue eosinophilia demonstrated higher levels of CRP (4.3 vs 1.9 mg/dl, P = 0.027) and ESR (62.1 vs 22.8 mm/h, P = 0.001). Among the 50 patients with RPF, the average number of tissue IgG4+ plasma cells was positively correlated with the number of tissue eosinophils (r = 0.37, P = 0.009). Moreover, serum IgG4 concentration and serum IgE concentration showed positive correlation (r = 0.834, P = 0.000).

CONCLUSION

The distinct serological and histopathological features of Chinese patients with IgG4-RPF were elevated serum IgE concentration and tissue eosinophilia, which potentially can aid and support the diagnosis. As serum IgG4 concentration may be normal in patients with IgG4-RPF, serum IgE may represent a useful serological marker in distinguishing IgG4-RPF from iRPF.

Ectopic relapse of IgG4-related disease presenting as IgG4-related sclerosing cholecystitis: A case report and review of literature

RATIONALE

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a chronic inflammatory disorder characterized by high levels of serum IgG4, swollen organs with fibrosis and abundant infiltration of IgG4-positive plasmacytes.

PATIENT CONCERNS

An 82-year-old male visited our hospital for an evaluation of a pancreatic enlargement and a bilateral submandibular adenopathy. Further investigation revealed elevation of serum IgG4 and bilateral lacrimal submandibular adenopathy. We diagnosed him with IgG4-related disease (IgG4-RD) and started administration of corticosteroid (CS) therapy. Both pancreatic enlargement and adenopathy rapidly improved; however, there was a new occurrence of diffuse wall thickening of the gallbladder during CS treatment.

DIAGNOSIS

Radiological examination revealed diffuse wall thickening of the gallbladder, and its inner layer was smooth and homogenous. These findings suggested an inflammatory change, but the possibility of malignancy could not be excluded.

INTERVENTIONS

The patient underwent laparoscopic cholecystectomy for a pathological diagnosis.

OUTCOMES

Histological examination revealed a transmural infiltration of IgG4 positive plasma cells and dense fibrosis. The patient was pathologically diagnosed with IgG4 related cholecystitis presenting as an ectopic relapse.

LESSONS

There are 2 major types of IgG4-related cholecystitis, a diffuse wall thickening type and a mass formation type. It is sometimes difficult to differentiate IgG4-related cholecystitis with gallbladder cancer.Corticosteroid (CS) is effective for induction of remission; however, we sometimes encounter disease relapse after reduction of CS dose. We should be mindful that some patients may relapse with new organ involvements even if the primary site and serum IgG4 level are well controlled.

Clivus Inflammatory Pseudotumor Associated with Immunoglobulin G4-Related Disease

BACKGROUND

Immunoglobulin G4 (IgG4)-related disease is a more recently recognized syndrome. It is characterized by increasing IgG4-positive plasma cells and lymphocyte infiltration. Reports of intracranial pseudotumors associated with IgG4-related disease are very rare. We report a rare case of clivus pseudotumor associated with IgG4-related disease mimicking meningioma.

CASE DESCRIPTION

A 50-year-old man presented with abducens paralysis of the right eye. Brain magnetic resonance imaging revealed a uniformly enhanced mass located in the right upper clivus area, and meningioma was highly suspected. The tumor was totally resected via a retrosigmoid approach craniotomy, which achieved sufficient decompression of the right abducens nerve. Postoperative pathology revealed IgG4-related disease with IgG4 strongly positive on immunohistochemical staining. The patient had no history of autoimmune disease. Postoperative laboratory data revealed no elevation of either IgG (6.94 g/L) or IgG4 (0.131 g/L). Follow-up contrast MRI showed the lesion had disappeared.

CONCLUSIONS

Although several cases of intrasellar hypophysitis have been reported, reports of intracranial pseudotumors associated with IgG4-related disease are rare. Special attention is required when the differential diagnosis includes meningioma. Preoperative diagnosis is very important because inflammatory pseudotumors associated with IgG4-related disease could be treated with steroid therapy, avoiding surgery.

Rituximab for retroperitoneal fibrosis due to IgG4-related disease: A case report and literature review

Retroperitoneal fibrosis (RPF) is a progressive fibroinflammatory disease that can be complicated by urinary obstruction. RPF can be the only manifestation of IgG4-related disease (IgG4-RD). Treatment of IgG4-related RPF is challenging and mostly consists of long-term glucocorticoids leading to significant side effects and treatment intolerance. Recent exploration of the role of rituximab as a B-cell depleting therapy in the treatment of IgG4-RD provides therapeutic potential as a well-tolerated alternative to glucocorticoids. We present a case of IgG4-related RPF for which rituximab was instituted as a steroid-sparing treatment strategy. Following 4 doses, kidney function partially recovered, and the disease went into remission. We discuss the potential merit of rituximab for the treatment of patients with IgG4-related RPF.

Immunoglobulin G4-Related Disease: An Update

Immunoglobulin G4-related disease (IgG4-RD) is an increasingly recognized immune-mediated condition comprised of a collection of disorders that share specific pathological, serological, and clinical features. IgG4-RD is a fibroinflammatory condition with a tendency to form tumors with inflammatory infiltrate with IgG4 rich plasma cells and elevation of serum IgG4, which may affect virtually every organ and tissue. IgG4-related ophthalmic disease may present as dacryoadenitis, myositis, or involvement of other orbital tissue. Hypophysitis or pachymeningitis may manifest as cranial neuropathies. The diagnosis of IgG4-RD is based on a typical clinical scenario, supportive laboratory test, expected radiological characteristics, and distinct histopathological and immunohistochemical features. Corticosteroids and immunosuppressives form the mainline treatment.

Infrequent organ involvement of IgG4-related diseases: a literature review

IgG4-related disease (IgG4-RD) is a chronic and systemic disease that can involve multiple organs. The most commonly involved organs include the salivary glands, orbital adnexal structures, paranasal sinus, thyroid, lungs, breasts, aorta, pancreas, biliary ducts, kidneys, retroperitoneum, lymph nodes, prostate, pituitary, and endocranium. Due to increased disease research, several new site-specific nuances of IgG4-RD have been described. The authors have reviewed the recent literature and briefly summarize the infrequent organ involvement of IgG4-RD.

A case of immunoglobulin G4-related lung disease with bilateral diffuse infiltration: A case report

RATIONALE

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a rare and chronic progressive autoimmune disease. It is a novel clinical entity characterized by elevated serum IgG4 concentration and tissue infiltration by IgG4 plasma cells. IgG4-related lung disease (IgG4-RLD) has been described as interstitial pneumonia and inflammatory pseudotumor, with various abnormal radiographic patterns. We report a case of IgG4-related lung disease with bilateral diffuse infiltration.

PATIENT CONCERNS

A 65-year-old woman was admitted to our hospital because of cough, sputum, and fever. Chest computed tomography (CT) revealed multifocal areas of consolidations, nodules, and ground glass opacities in both lungs. She still had fever after anti-infective therapy.

DIAGNOSES

Bronchial bronchoscopy and percutaneous lung biopsy were performed, resulted in a pathological diagnosis of IgG4-RLD.

INTERVENTIONS

The patient was started on oral prednisolone 30 mg/day for 28 days, and then was gradually tapered.

OUTCOMES

After one week treatment, the temperature was stable, CT showed significant improvement in the areas of consolidations and nodules.

LESSONS

It is a typical case of IgG4-RLD. This case indicated that suggestive evidence, radiological appearances, serum tests, pathological characteristics, and classic therapy IgG4-RLD. It is a rare disease that needs our more attention in future.

The variety of clinical presentations in IgG4-related disease in Rheumatology

IgG4-related disease (IgG4-RD) belongs to the group of rare diseases in which the identification of the characteristic histology and immunohistochemistry provides with the gold standard in the diagnosis. The variable organ dysfunction reflects the clinical presentation. The examples of different IgG4-RD presentations in the Rheumatology Unit were discussed in this article. The spectrum of IgG4-RD is wide-ranging and manifested in one or more organs synchronously or metachronously. In the presented article, we described five different cases of IgG4-RD. Four cases were reaffirmed in the histopathological assessment. The clinical and laboratory findings were analyzed and the assigned therapy was discussed. According to our experience, the diagnosis of IgG4-RD requires the careful clinicopathological correlation. The diagnosis relies on the coexistence of various clinical, laboratory, radiological, and histopathological findings, although none of them is pathognomonic itself. The time needed for the diagnosis and variety of clinical forms of IgG4-RD shows that there is need of the cooperation among many specialists for the better and earlier recognition of the disease.

Neurological Manifestations of IgG4-Related Disease

OPINION STATEMENT

IgG4-related disease (IgG4-RD) is a multisystem inflammatory disorder. Early recognition of IgG4-RD is important to avoid permanent organ dysfunction and disability. Neurological involvement by IgG4-RD is relatively uncommon, but well recognised-hypertrophic pachymeningitis and hypophysitis are the most frequent manifestations. Although the nervous system may be involved in isolation, this more frequently occurs in conjunction with involvement of other systems. Elevated circulating levels of IgG4 are suggestive of the condition, but these are not pathognomonic and exclusion of other inflammatory disorders including vasculitis is required. Wherever possible, a tissue diagnosis should be established. The characteristic histopathological changes include a lymphoplasmacytoid infiltrate, storiform fibrosis and obliterative phlebitis. IgG4-RD typically responds well to treatment with glucocorticoids, although relapse is relatively common and treatment with a steroid-sparing agent or rituximab may be required. Improved understanding of the pathogenesis of IgG4-RD is likely to lead to the development of more specific disease treatments in the future.

Recent advances in knowledge regarding the head and neck manifestations of IgG4-related disease

IgG4-related disease (IgG4-RD) is a chronic inflammatory disorder, characterized by elevated serum IgG4 levels as well as abundant infiltration of IgG4-positive plasmacytes and fibrosis in various organs, including the head and neck region. In particular, the salivary glands, orbit, and thyroid are common sites of disease involvement. IgG4-RD is diagnosed based on various clinical, serological, and histopathological findings, none of which are pathognomonic. Hence, various differential diagnoses, which exhibit elevated serum IgG4 levels and infiltration of IgG4-postive cells into tissues, need to be excluded, especially malignant diseases and mimicking disorders. Systemic corticosteroids are generally effective in inducing IgG4-RD remission; however, recurrent or refractory cases are common. In addition, although the pathogenic mechanisms of IgG4-RD remain unclear, an antigen-driven inflammatory condition is believed to be involved. Recent studies have indicated the important pathogenic role of B cell/T cell collaboration and innate immunity in this disease. Nevertheless, additional research and discussions are needed to resolve many remaining questions. In this review, we provide an overview of the recent insights on the history, clinical features, diagnosis, and treatment of IgG4-RD in the head and neck region. Furthermore, we have also addressed the pathogenesis of this disease.

The Differential Diagnosis of Dry Eyes, Dry Mouth, and Parotidomegaly: A Comprehensive Review

Primary Sjögren's syndrome (pSS) is a frequent autoimmune systemic disease, clinically characterized by eyes and mouth dryness in all patients, salivary gland swelling or extraglandular systemic manifestations in half of the patients, and development of lymphoma in 5 to 10 % of the patients. However, patients presenting with sicca symptoms or salivary gland swelling may have a variety of conditions that may require very different investigations, treatments, or follow-up. Eye and/or mouth dryness is a frequent complaint in clinical setting, and its frequency increases with age. When evaluating a patient with suspected pSS, the first step is to rule out its differential diagnoses, before looking for positive arguments for the disease. Knowledge of normal and abnormal lachrymal and salivary gland physiology allows the clinician to prescribe the most adapted procedures for evaluating their function and structure. New tests have been developed in recent years for evaluating these patients, notably new ocular surface staining scores or salivary gland ultrasonography. We describe the different diagnoses performed in our monocentric cohort of 240 patients with suspected pSS. The most frequent diagnoses are pSS, other systemic autoimmune diseases, idiopathic sicca syndrome and drug-induced sicca syndrome. However, other diseases are important to rule out due to their specific management, such as sarcoidosis, granulomatosis with polyangeitis, IgG4-related disease, chronic hepatitis C virus or human immunodeficiency virus infections, graft-versus-host disease, and head and neck radiation therapy. At the light of these data, we propose a core of minimal investigations to be performed when evaluating a patient with suspected pSS.

IgG4-related disease: a case report with duration of more than 16 years and review of literature

Introduction

IgG4-related disease was first reported in 2001 and was officially named in 2010. It is now considered as a systemic disease that might affect any organ system. The characteristic pathological changes of IgG4-related disease are extensive infiltration of IgG4-positive plasma cells. IgG4-related disease is a kind of benign lesions, but there has not been well-defined standard treatment so far. Patients usually respond well to corticosteroids. The prognosis of IgG4-related disease is perhaps good as long as early detection and treatment.

Case description

We report one case of IgG4-related disease with a 16-years anamnesis with multi-pseudotumor masses. He was diagnosed with chronic kidney disease with wide interstitial renal fibrosis. And he received glucocorticoids therapy. After 2 month therapy, the serum creatinine, erythrocyte sedimentation rate, and serum IgG4 decreased significantly. The discussion includes presentation, clinical course, diagnosis, and prognosis of IgG4-related disease. The case and discussion highlight the importance of diagnosis and the good prognosis of IgG4-related diseases.

Discussion and evaluation

Our case highlights the importance of diagnosis and the good prognosis of IgG4-related diseases. IgG4-related disease is a systemic fibro-inflammatory immune-mediated disorder and now recognized in almost every major organs. Characteristics of the disease is multiple lymph nodes and the response to glucocorticoids therapy is well. In such case, he had a history of 16 years with multi-pseudotumor masses and misdiagnosed for 16 years, if the doctors were not awareness of higher serum immunoglobulin G4 (IgG4) than normal, the correct diagnosis may be missed or delayed. Consequently, appropriate treatment for IgG4-related disease would also be delayed or not provided and likely result in increased morbidity and mortality.

Conclusions

IgG4-related disease is a systemic fibro-inflammatory immune-mediated disorder and progresses slowly. In the present patient the course of IgG4-related disease appears to be benign. The prognosis of IgG4-related disease depend on early diagnosis and treatment.