Diagnosis Of IgG4-related Disease Research Articles

Increased prevalence of malignancies in patients with IgG4-related disease: implications for clinical care.

The association between cancer and IgG4-related disease (IgG4-RD) is evolving. The primary aim of this study was to investigate the prevalence of malignancies in IgG4-RD. The secondary aim was to describe the epidemiological and clinical characteristics of IgG4-RD patients with a history of cancer. Two hundred and ten patients with IgG4-RD were included in this retrospective study. IgG4-RD phenotypes, clinical and serological variables were analyzed. The prevalence of cancer in IgG4-RD was compared with that in the Italian population using the registry of the Global Cancer Observatory (GCO) of the World Health Organization. The Standardized Incidence Ratio (SIR) for cancer in IgG4-RD was obtained based on the 5-years Limited Duration Prevalence (2015-2020) of tumors in the Italian population. Thirty-seven/210 patients (18%) developed cancer before or after the diagnosis of IgG4-RD. Solid and hematologic tumors were more frequently observed in pancreato-biliary IgG4-RD. The SIR for malignancy in IgG4-RD patients was 2.54 higher than the general Italian population (p= 0.007). The SIR was 2.78 higher for males (p= 0.005) and 1.15 higher for females (p> 0.05). Thirty-two malignancies were diagnosed before and 16 after IgG4-RD diagnosis. Interval "from IgG4-RD to cancer" was shorter than that "from cancer to IgG4-RD". Most tumors occurring after IgG4-RD developed within 36 months from diagnosis of IgG4-RD. The prevalence of cancer in patients with IgG4-RD is increased compared with the Italian population and mechanistically suggests a possible paraneoplastic association. Close surveillance is warranted for the first 36 months after IgG4-RD diagnosis.

Radiology domain in the diagnosis of IgG4-RD according to the 2019 American College of Rheumatology and European League Against Rheumatism classification

ObjectivesTo evaluate the performance of radiology-related inclusion criteria of the 2019 ACR-EULAR classification system in the diagnosis of IgG4-related disease (IgG4-RD).MethodsThis retrospective single-institution study included patients who received a diagnosis of IgG4-RD between January 2010 and December 2020. Two abdominal radiologists independently reviewed baseline imaging studies and scored radiology findings according to the 2019 ACR-EULAR classification criteria. Additional scores were assigned based on serological, histopathological, and immunostaining features.ResultsSeventy-four patients (58 males and 16 females) with a mean age of 59.3 ± 13.9 years diagnosed with IgG4-RD were included. 51/74 (68.9%) were classified as having IgG4-RD according to the 2019 ACR-EULAR classification criteria. To reach a score ≥ 20 in these 51 patients, the radiology domain was sufficient in 20/51 (39.2%) and adding the serology domain was required for another 20/51 (39.2%). The remaining 11/51 patients (21.6%) required the histopathology and immunostaining domains. Radiological involvement of two or more organs at presentation was significantly associated with a score of ≥ 20 and seen in 43/51 (84.3%) compared to 5/23 (21.7%) of the non-classified group (p < 0.001). The group classified as having IgG4-RD showed a significantly higher proportion of elevated IgG4 levels (39/51, 76.5%) than the non-classified group (8/23, 34.8%) (< 0.001).ConclusionThe study findings support the effectiveness of the radiology-related inclusion criteria of the 2019 ACR-EULAR classification system in diagnosing IgG4-RD. Combining radiology and serology domains achieved the cut-off in 80% of IgG-RD patients, enabling non-invasive diagnosis. The classification of IgG4-RD was significantly associated with multi-organ involvement, particularly affecting the pancreas and biliary system.Critical relevance statementThis study is the first to evaluate the diagnostic performance of the radiology domain in the 2019 ACR-EULAR classification criteria. The study results confirm its utility and potential to enable non-invasive diagnosis when combined with serological testing in a significant proportion of patients.Key points• A significant proportion of patients can be diagnosed with IgG4-RD using the radiology and serology domains exclusively.• Multi-organ involvement is significantly associated with classifying patients as IgG4-RD, with the pancreas and biliary system most frequently affected.• A high level of inter-reader agreement in the scoring of the radiology domain supports its reliability.Graphical

IgG4-related disease presenting as a pancreatic mass: A case report

Immunoglobulin G4-related disease (IgG4-RD) is an increasingly recognized fibroinflammatory condition with characteristic clinical, serological, and histopathological features. It might involve any organ in the body with a special predilection for lymph nodes, salivary glands, the pancreas, and the retroperitoneum. Due to the non-specific features of the disease and the capability of mimicking many other medical conditions, the diagnosis of IgG4-RD could be delayed. Herin, we describe a case of a middle-aged man who presented with obstructive jaundice due to a pancreatic mass. Further evaluation revealed multiple cervical and inguinal lymphadenopathy, bilateral wedge-shaped lesions in the kidneys and substantial thickening of the aortic wall that was suggestive of aortitis/periaortitis. A histopathological examination of an inguinal lymph node showed increased infiltration of nodal immunoglobulin G4 (IgG4) plasma cells (&gt;30/high-power field) with a high serum IgG4 immunoglobulin level. Based on that, the patient was diagnosed with IgG4-RD, and he was successfully treated with pulse steroid therapy with complete resolution of his symptoms and the radiological and laboratory findings. IgG4-RD is a protean condition with a large spectrum of clinical manifestations that could mimic many other serious medical conditions. Early recognition and management of immunosuppression are vital for complete recovery.

Validation of the Diagnostic Criteria for IgG4-Related Periaortitis/Periarteritis and Retroperitoneal Fibrosis (IgG4PA/RPF) 2018, and Proposal of a Revised 2023 Version for IgG4-Related Cardiovascular/Retroperitoneal Disease.

In 2018, diagnostic criteria were introduced for IgG4-related periaortitis/periarteritis and retroperitoneal fibrosis (PA/RPF). This study assessed the existing criteria and formulated an improved version.Methods and Results: Between August 2022 and January 2023, we retrospectively analyzed 110 Japanese patients diagnosed with IgG4-related disease (IgG4-RD) involving cardiovascular and/or retroperitoneal manifestations, along with 73 non-IgG4-RD patients ("mimickers") identified by experts. Patients were stratified into derivation (n=88) and validation (n=95) groups. Classification as IgG4-RD or non-IgG4-RD was based on the 2018 diagnostic criteria and various revised versions. Sensitivity and specificity were calculated using experts' diagnosis as the gold standard for the diagnosis of true IgG4-RD and mimickers. In the derivation group, the 2018 criteria showed 58.5% sensitivity and 100% specificity. The revised version, incorporating "radiologic findings of pericarditis", "eosinophilic infiltration or lymphoid follicles", and "probable diagnosis of extra-PA/-RPF lesions", improved sensitivity to 69.8% while maintaining 100% specificity. In the validation group, the original and revised criteria had sensitivities of 68.4% and 77.2%, respectively, and specificities of 97.4% and 94.7%, respectively. Proposed 2023 revised IgG4-related cardiovascular/retroperitoneal disease criteria show significantly enhanced sensitivity while preserving high specificity, achieved through the inclusion of new items in radiologic, pathological, and extra-cardiovascular/retroperitoneal organ categories.

Current and future advances in practice: IgG4-related disease.

IgG4-related disease (IgG4-RD) is an increasingly recognized cause of fibroinflammatory lesions in patients of diverse racial and ethnic backgrounds and is associated with an increased risk of death. The aetiology of IgG4-RD is incompletely understood, but evidence to date suggests that B and T cells are important players in pathogenesis, both of which are key targets of ongoing drug development programmes. The diagnosis of IgG4-RD requires clinicopathological correlation because there is no highly specific or sensitive test. Glucocorticoids are highly effective, but their use is limited by toxicity, highlighting the need for studies investigating the efficacy of glucocorticoid-sparing agents. B cell-targeted therapies, particularly rituximab, have demonstrated benefit, but no randomized clinical trials have evaluated their efficacy. If untreated or under-treated, IgG4-RD can cause irreversible organ damage, hence close monitoring and consideration for long-term immunosuppression is warranted in certain cases.

Urinary bladder involvement in IgG4-related disease: A case-based review.

Immunoglobulin G4-related disease (IgG4-RD) is an immune-driven fibroinflammatory disease that presents as tumefactive lesions that not only commonly affects the pancreas, lacrimal and salivary glands, lung, liver and kidney but can also affect any organs. However, involvement of the urinary bladder in IgG4-RD is rarely reported. We describe a case of IgG4-RD involving the urinary bladder mimicking carcinoma and review the published literature-a 39-year-old male presented with complaints of dysuria, urgency and hesitancy. Ultrasound revealed a hyperechoic lesion protruding from the anterior of the urinary bladder wall with partial obstruction to bladder outflow, likely to be a pedunculated bladder mass with high suspicion for malignancy. A contrast-enhanced computed tomography abdomen showed a large irregular lobulated heterogeneously enhancing lesion involving the anteroinferior wall of the urinary bladder extending from mid-body up to the neck region with significant perivesical fat stranding and multiple ill-defined perivesical deposits along with hypodense soft tissue lesion in the perigastric region at the level of the body of the stomach. CT-guided perigastric and ultrasound-guided biopsy from the urinary bladder mass confirmed the diagnosis of IgG4-RD. The patient was treated with glucocorticoids. He is doing well after a 1-year follow-up without recurrence, and a repeat ultrasound showed a significant reduction in the size of the urinary bladder mass. The diagnosis of IgG4-RD should be considered in the differential diagnosis of a urinary bladder mass. High index of suspicion and prompt initiation of therapy are required to minimise residual damage and the need for surgical intervention.

Diagnostic challenges of the idiopathic plasmacytic lymphadenopathy (IPL) subtype of idiopathic multicentric Castleman disease (iMCD): Factors to differentiate from IgG4-related disease

Aims and methodsIdiopathic multicentric Castleman disease (iMCD) is currently considered to be classified into three clinical subtypes, including idiopathic plasmacytic lymphadenopathy (IPL), thrombocytopaenia, anasarca, fever, reticulin fibrosis/renal dysfunction, organomegaly (TAFRO)...

Mass spectrometry in IgG4-related disease diagnosis

We compared liquid chromatography tandem mass spectrometry (LC–MS/MS) against Binding Site immunonephelometry (BSIN) with regards to these methods’ abilities to diagnose IgG4-related disease (IgG4-RD). IgG subclasses were gathered from laboratory from December 2011 to December 2020. The IgG4-RD positive and negative patients were diagnosed according to the ACR/EULAR classification criteria by extensive chart review. Both methods’ results were compared in terms of test characteristics. For BSIN, there were 43 IgG4-RD positive cases and 174 disease negative cases, while for LC–MS/MS, there were 102 IgG4-RD positive cases and 562 disease negative cases. The majority of IgG4-RD patients by BSIN and LC–MS/MS had an elevated IgG4 level, 81% and 86%, respectively. For BSIN, the ROC curve, cut-off value of 1.25 g/L, had a sensitivity of 81% and a specificity of 84%. For LC–MS/MS, the ROC curve, cut-off value of 1.25 g/L, had a sensitivity of 86% and a specificity of 84%. The responder index score to IgG4 level r-correlation value for BSIN and LC–MS/MS was 0.5 and 0.6, respectively. In our center, LC–MS/MS and BSIN are equivalent test methods in IgG4-RD diagnosis. IgG4 level does correlate with disease activity by the responder index. LC–MS/MS is a valid and equally reliable alternative to BSIN in the diagnosis of IgG4-related disease.

IgG4 related disease masquerading as a sinonasal mass: a case report and review of literature

IgG4-related disease (IgG4-RD) is a relatively new autoimmune fibroinflammatory disease. Most seen to affect the pancreas and biliary tract, IgG4-RD of the nose and paranasal sinuses is very rare. Known to have tumour-like clinical presentations, they can present with varying levels of dysfunction of the organs they affect. In the paranasal sinuses, it can present with nasal block, discharge, bleeds, and sometimes, with symptoms that arise as a consequence of bony erosions and subsequent extension of the disease. We present a case of a 52-year-old lady, who presented with a painful swelling over the malar region with discoloration of the overlying skin. Radiological evaluation helps to check for bony erosions and soft tissue infiltration. Histopathology with immunohistochemistry helps to confirm the diagnosis of IgG4-RD. Most patients benefit from a long course of oral steroids and regular follow-ups, that help to prevent recurrence and ensure a good quality of life for the patient.

The assessment of 18F-FDG PET/CT in IgG4-related disease: Case report and review of the literature

Immunoglobulin G4-related disease (IgG4-RD) is easily misdiagnosed. We report a case of IgG4-RD, whose main complaint was swollen eyelids, revealed by 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/computed tomography (PET/CT) and confirmed by pathological analysis from the submaxillary nodes. A 49-year-old woman complained about a bilateral swollen eyelid with blurred vision for 2 years. An enlarged submandibular lymph node was found during a physical examination. Head-enhanced magnetic resonance imaging (MRI) showed that the nasopharyngeal soft tissues were thickened, and the bilateral cervical lymph nodes were enlarged. A nasopharyngoscopy and tissue biopsy indicated chronic inflammation. 18F-FDG PET/CT was taken to eliminate malignant tumor metastasis, and the results suggest autoimmune disease. A biopsy of submandibular lymphatic nodes was taken, and the immunohistochemical staining showed IgG4-positive cells. Finally, IgG4-RD was diagnosed with elevated serum IgG4. The diagnosis of IgG4-RD is based on a comprehensive judgment of clinical symptoms, serum IgG4 levels, imaging studies, and pathological evidence. Ophthalmologists should be aware of the general conditions of patients who complain of unexplained ocular swelling, and 18F-FDG PEC/CT is strongly recommended. Compared with histopathologic examination, 18F-FDG PEC/CT can display changes in morphology and metabolism in involved organs and is noninvasive. It can be helpful in detecting, diagnosing, characterizing, and monitoring the response of the IgG4-RD.

IgG4-related disease - a clinical case

Immunoglobulin G4-related disease (IgG4-RD) is a systemic disease affecting one or more organs. Pathomorphologically, a dense infiltrate of lymphocytes and IgG4 plasmocytes, and subsequent fibrosis is detected. Despite the many hypotheses of genetic predisposition, molecular mimicry and autoimmune nature of the disease, the etiology still remains unclear. Both innate and acquired immunity are believed to play a key role in disease pathogenesis. The involvement of occupational risk factors is also discussed. The possible involvement of multiple organs and systems (most often lacrimal and salivary glands, kidneys, lungs, aorta, pancreas, hepatobiliary duct, lymph nodes, as well as retroperitoneal fibrosis) is the reason for the multidisciplinary approach in this disease. In pulmonary involvement, clinical manifestations are nonspecific (cough, dyspnea, chest or back pain, hemoptysis, low-grade fever, weight loss) or patients are asymptomatic and pulmonary changes are an incidental finding on imaging. Up to 60% of cases of autoimmune pancreatitis represent a pancreatic manifestation of IgG4-related disease, with the majority of patients being elderly men. The most common differential diagnosis is a malignant process due to the tumor-like changes of the affected organ. Treatment with corticosteroids, immunosuppressors and symptomatic agents in most cases has a good effect, although relapses of the disease are also observed. We present a clinical case of a 72-year-old patient whose first complaints were nonspecific, for which a chest computed tomography was performed with visualization of four solid nodules in the right lung. After antibiotic therapy, without effect and deterioration of the patient's condition, video-assisted thoracoscopy, biopsy, histology and immunohistochemistry were performed. A diagnosis of IgG4-RD with pleural and lung involvement was confirmed. Anemic syndrome, increased values ​​of amylase, lipase, and acute phase parameters were found from the laboratory tests. Through endoscopic retrograde cholangio-pancreatography, autoimmune pancreatitis was diagnosed in the course of IgG4-RD. A plastic stent was placed on the common bile duct. Treatment with Prednisolone 40 mg/day was started with a subsequent dose reduction. Follow-up computed tomography of the lung after 9 months demonstrated a reduction of the described changes in the lungs, but with persistent lymphadenopathy and fibrotic changes. Azathioprine 100 mg daily was added to prednisone therapy. Against the background of the combined treatment, an improvement of the clinical condition and laboratory parameters was established.

A rare clinical observation of ureteral IgG4-related disease in urological practice: A case report

IgG4-related disease (IgG4-RD) is a systemic immune-dependent pathology marked by infiltration of lymphocytes and plasma cells expressing IgG4 in affected tissues, leading to phlebitis and fibrosclerosis. In urological practice, diagnosing IgG4-RD of the ureter, which may resemble a malignant tumor, presents challenges. We present a unique case: a 64-year-old patient (Patient P.) experienced left lumbar discomfort and a 4 kg weight loss over 2 months. A computed tomography scan revealed a 111 mm tumor obstructing the left ureter, causing hydronephrosis and regional lymphadenopathy. Suspecting ureteral urothelial cancer, the patient underwent a left nephroureterectomy with lymphadenectomy. Microscopic analysis revealed fibrosis and inflammation infiltration (lymphocytes, plasma cells, and eosinophils) in the ureter wall, with no evidence of tumor growth. Immunohistochemistry confirmed IgG4-positive plasma cells. Serum IgG4 rose to 149 mg/dL. Morphological findings led to a diagnosis of IgG4-RD of the ureter. Clinically, it is crucial to recognize IgG4-RD in ureteral neoplasms for early detection, to prevent unnecessary surgical intervention.

Immunoglobulin G4-Related Lesions in Autoimmune Diseases: Unusual Presentations at Atypical Sites-A Tale of 2 Cases with Literature Review.

Immunoglobulin G4-related disease (IgG4-RD) coexisting with clinically apparent autoimmune diseases, such as rheumatoid arthritis (RA) or antiphospholipid syndrome (APS), is a rarely documented combination in the scientific literature. In this case-based review, we present 2 intriguing cases with preexisting autoimmune diseases, namely, RA and primary APS, who exhibited coexistent IgG4- related lesions at unusual sites. The first case pertains to a patient with known RA who presented with an encasing mass in the esophagus leading to stricture, with histopathological diagnosis of IgG4-RD.The second patient, diagnosed with primary APS, experienced breathlessness, and imaging revealed a right atrial mass. Histopathological examination of the mass confirmed IgG4-RD. Notably, both patients demonstrated significant clinical improvement upon initiation of steroid therapy. Rheumatoid arthritis patients commonly exhibit elevated levels of IgG4 in their sera; however, RA with coexisting IgG4-RD is rarely reported in the literature. Similarly, APS with IgG4-related lesions is exceedingly rare. Although there are few case reports and series on esophageal and cardiac IgG4-RD, the occurrence of such unusual location of IgG4-related lesions in the context of known autoimmunity is presented here for the first time.

THU369 A Rare Case Of IgG4-related Autoimmune Pancreatitis And Diabetes Mellitus

Abstract Disclosure: M. Zahid: None. J. Shakil: None. Introduction: IgG4 related disease (IgG4-RD) is a rare multiorgan inflammatory condition characterized by dense lymphoplasmacytic infiltrates, presence of IgG4+ plasma cells and fibrosis. Here we present a case of young male with painless jaundice and hyperglycemia diagnosed with IgG4 related autoimmune pancreatitis and DM. Clinical Case: 46-year-old male with no significant history presented to outpatient clinic for pruritis and dark-colored urine of 2-week onset. He reported 17-pounds weight loss in the preceding month. While undergoing outpatient workup, patient developed epigastric pain prompting visit to the hospital. On examination, patient was afebrile, tachycardiac, icteric and had epigastric tenderness. Labs revealed normal electrolytes and renal function. LFTs were significant for total protein 7.6 g/dl (n=6.3-8.3 g/dl), AST 77 U/L (n = 10-50 U/L), ALT 127 U/L (n = 5-50 U/L), alkaline phosphatase 458 U/L (n = 40-129 U/L) and direct bilirubin &amp;gt;10.0 (n = 0-0.3 mg/dl). Lipase was 99 U/L (n - 13-60 U/L), blood glucose was 292 mg/dl and A1C was 6.5% (n = 4.0-5.6%). US abdomen revealed diffuse gallbladder wall thickening with moderate sludge and intrahepatic and extrahepatic distal biliary obstruction and dilatation. MRCP showed common bile duct and intrahepatic biliary ductal dilation. Pancreas was diffusely irregular with areas of hemorrhagic pancreatitis. ERCP showed dilatation of upper and middle third of main bile duct, left and right hepatic ducts and all intrahepatic branches with a stricture in distal bile duct. Biliary sphincterotomy and placement of temporary plastic biliary stent was performed and ampullary biopsies were taken. IgG4 level was checked due to suspicion for IgG4-RD and was 293 mg/dl (n: 1-123 mg/dl). Pathology revealed mucosa with epithelial reactive changes. CD138 stain showed several mature plasma cells within the inflammatory infiltrate. In addition, immunostain for IgG4 shows several IgG4 positive plasma cells forming small clusters confirming diagnosis of IgG4-RD. Post procedure, his abdominal pain and LFTs started improving. Patient was started on prednisone for IgG4-RD and insulin for persistent hyperglycemia. His prednisone dose was later tapered after starting methotrexate. Patient’s most recent LFTs have normalized except mildly elevated ALT and A1C improved to 6.2%. Conclusion: Autoimmune pancreatitis and cholangiopathy are the pancreatobiliary manifestation of IgG4-RD and most often present as painless jaundice mimicking pancreatic cancer. Endocrine insufficiency usually manifests as diabetes mellitus/pre-diabetes and may also lead to autoimmune hypophysitis and Reidel’s fibrosis. Other organ systems that may also get involved include lacrimal and salivary glands, lungs, kidneys, nervous system, and lymphatic/vascular system. Early recognition and ongoing surveillance are key to appropriate management of this condition. Presentation: Thursday, June 15, 2023

Recommendations for the diagnosis and treatment of IgG4-related disease in China

IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition characterized by tumefactive lesions in multi-organs. It is a novel entity presented by variable manifestations. In recent years, there has been progress toward recognizing IgG4-RD. However, the diagnosis and treatment of IgG4-RD still present challenges due to insufficient experience. To address this, the Chinese Rheumatology Association has developed standardized guidelines for the diagnosis and treatment of IgG4-RD based on domestic and international experience. These guidelines aim to enhance the understanding and management of IgG4-RD, ultimately improving the prognosis for patients with IgG4-RD.

Therapeutic Uses of Rituximab and Clinical Features in Immunoglobulin G4-Related Disease: A Systematic Review.

This research presents a systematic review focusing on rituximab's therapeutic applications in immunoglobulin G4 (IgG4)-related disease (IgG4-RD), a rare condition characterized by immune-mediated systemic inflammation and tissue fibrosis, as well as the clinical features of IgG4-RD. While the disease commonly affects organs such as the bile ducts, lymph nodes, retroperitoneum, pancreas, and salivary glands, it can potentially involve other organs. This intricacy often leads to diagnostic challenges due to clinical overlaps with cancer, infections, and other autoimmune disorders. The diagnosis of IgG4-RD necessitates a comprehensive approach involving laboratory tests, imaging studies, and clinical assessments. Symptoms can vary, ranging from lymphadenopathy to jaundice, affecting multiple organs. Although elevated blood IgG4 levels and findings of tissue involvement and fibrosis on imaging can be suggestive, they lack the specificity for a definitive diagnosis. Early diagnosis is crucial for initiating corticosteroids and immunosuppressive to prevent further damage from IgG4-RD. This study highlights the therapeutic role of rituximab in managing this condition. Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria, the research identifies and evaluates relevant literature across various electronic databases, including PubMed, ScienceDirect, and Google Scholar. This review includes 14 selected publications, comprising three systematic reviews, three observational studies, four narrative reviews, and four case reports. The study design ensures a comprehensive evaluation of rituximab's potential efficacy in treating IgG4-RD and its associated clinical characteristics. Based on this study, it can be concluded that IgG4-RD can potentially be treated with rituximab, particularly in cases of relapse and maintaining remission.

IgG4-Related Disease, a Systemic or Local Disease: This is the Problem

Background: Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition that forms tumefactive lesions in various organs, presenting with diverse clinical manifestations. Diagnosis of IgG4-RD could be challenging and relies on characteristic histopathological findings and elevated IgG4+ plasma cell counts. Case Presentation: The patient was a 48-year-old woman with diabetes mellitus initially presented with a painless breast mass. Imaging indicated irregular opacities and lymph nodes in the breast. Biopsy results revealed lymphoplasmacytic infiltration with IgG and IgG4 positivity, overall compatible with IG4-related disease. A mass resection was performed, and intraoperative assessment ruled out malignancy. Then, with a 5-month interval of no symptoms, the patient developed a cheek mass, initially misdiagnosed as low-grade spindle cell sarcoma. Subsequently, she underwent partial maxillectomy and further examination and histology confirmed IgG4-RD, meeting all diagnostic criteria. Conclusion: IgG4-RD is a rare, systemic fibroinflammatory condition with potential to mimic neoplastic processes. While IgG4 serum levels can be elevated, they are not a reliable diagnostic criterion. The two main features of IgG-related disease are an elevated number of IgG4-positive plasma cells within the tissue and a characteristic histopathological appearance including a dense lymphoplasmacytic infiltrate, storiform fibrosis, and obliterative phlebitis. Overall, diagnosis is based on the balance of clinical features, histopathology, and serum markers. This case underscores the diagnostic challenges posed by IgG4-RD, often mistaken for malignancies due to its invasive behavior and emphasizes the importance of considering IgG4-RD in differential diagnoses for tumor-like lesions, particularly when affecting multiple organs, to enable timely treatment decisions and prevent unnecessary interventions.

IgG4-Related Disease: A Concise Review

IgG4-related disease (IgG4-RD) is a multi-organ fibroinflammatory disorder that may result in organ dysfunction and complications. Glucocorticoids remain the primary treatment for inducing remission, while recently reported disease phenotypes might inform personalized therapeutic strategies. Progress in understanding the pathophysiology of IgG4-RD has led to the identification of novel treatment targets. Ongoing research will further refine the optimal treatment for IgG4-RD. This review offers an update on the latest evidence on the epidemiology, pathogenesis, clinical features, diagnosis, and treatment of IgG4-RD.

Renal Involvement of Immunoglobulin G4-Related Disease Presenting as a Solitary Hypermetabolic Mass Mimicking Renal Tumor on 18F-FDG PET/CT.

A 62-year-old woman with a 5-year history of diabetes insipidus was found with a solitary renal mass in contrast-enhanced CT. 18F-FDG PET/CT showed a hypermetabolic mass in the right kidney. Besides, there was increased uptake in the pituitary stalk. The histopathological examination of renal biopsy confirmed the diagnosis of immunoglobulin G4-related disease. After treatment with prednisone and cyclophosphamide, there was obvious radiographic improvement of the renal lesion.

Clinical Significance of Serum IgG4 in the Diagnosis and Treatment Response of IgG4-Related Disease in Adults of Southwest China: A Retrospective Study.

There is no standard cut-off value of serum IgG4 concentration and serum IgG4/total IgG ratio for the diagnosis of IgG4-related disease (IgG4-RD) or as a marker of treatment responses. We aimed to explore this issue through a retrospective cohort analysis of adults in southwest China. The diagnostic performance of serum IgG4 concentration and IgG4/IgG ratio for IgG4-RD was evaluated in a retrospective analysis of 177 adults newly diagnosed as having IgG4-RD and 877 adults without IgG4-RD. Dynamic analysis was performed to evaluate the significance of serum IgG4 concentration on IgG4-RD treatment responses. The serum IgG4 concentration differed according to sex. The optimal cut-off values of serum IgG4 concentration and IgG4/IgG ratio for IgG4-RD diagnosis were 1.92 g/L and 0.12 in males and 1.83 g/L and 0.11 in females, respectively. For patients with serum IgG4 concentration >2.01 g/L, the cut-off values in the total population were >3.00 g/L and 0.19, respectively. The median serum IgG4 concentration decreased over time, and the decrease rate increased over time. The serum IgG4 concentration significantly decreased at >1 week post-treatment (P=0.004), and the median decrease rate was close to 50% at >4 weeks post-treatment. Serum IgG4 can be a good indicator for IgG4-RD diagnosis; however, different diagnostic cut-off values should be determined according to sex. The decreasing rate is more conducive than the serum IgG4 concentration to monitor treatment efficacy. The IgG4/IgG ratio did not improve the diagnostic efficacy for IgG4-RD.