Immunoglobulin G4-related spinal pachymeningitis:A case report

BACKGROUND Immunoglobulin G4-related disease(IgG4-RD)is a complex immune-mediated condition that causes fibrotic inflammation in several organs.A significant clinical feature of IgG4-RD is hypertrophic pachymeningitis,which manifests as inflammation of the dura mater in intracranial or spinal regions.Although IgG4-RD can affect multiple areas,the spine is a relatively rare site compared to the more frequent involvement of intracranial structures.CASE SUMMARY A 70-year-old male presented to our hospital with a two-day history of fever,altered mental status,and generalized weakness.The initial brain magnetic resonance imaging(MRI)revealed multiple small infarcts across various cerebral regions.On the second day after admission,a physical examination revealed motor weakness in both lower extremities and diminished sensation in the right lower extremity.Electromyographic evaluation revealed findings consistent with acute motor sensory neuropathy.Despite initial management with intravenous immunoglobulin for presumed Guillain-Barrésyndrome,the patient exhibited progressive worsening of motor deficits.On the 45th day of hospitalization,an enhanced MRI of the entire spine,focusing specifically on the thoracic 9 to lumbar 1 vertebral level,raised the suspicion of IgG4-related spinal pachymeningitis.Subsequently,the patient was administered oral prednisolone and participated in a comprehensive rehabilitation program that included gait training and lower extremity strengthening exercises.CONCLUSION IgG4-related spinal pachymeningitis,diagnosed on MRI,was treated with corticosteroids and a structured rehabilitation regimen,leading to significant improvement.

Immunoglobulin G4 associated autoimmune cholangitis and pancreatitis following the administration of nivolumab:A case report

BACKGROUND Immune checkpoint inhibitors have significantly improved survivals for an increasing range of malignancies but at the cost of several immune-related adverse events,the management of which can be challenging due to its mimicry of other autoimmune related disorders such as immunoglobulin G4(IgG4)related disease when the pancreaticobiliary system is affected.Nivolumab,an IgG4 monoclonal antibody,has been associated with cholangitis and pancreatitis,however its association with IgG4 related disease has not been reported to date.CASE SUMMARY We present a case of immune-related pancreatitis and cholangiopathy in a patient who completed treatment with nivolumab for anal squamous cell carcinoma.Patients IgG4 levels was normal on presentation.She responded to steroids but due to concerns for malignant biliary stricture,she opted for surgery,the pathology of which suggested IgG4 related disease.CONCLUSION We hypothesize this case of IgG4 related cholangitis and pancreatitis was likely triggered by nivolumab.

Clinical and pathological differences between serum immunoglobulin G4-positive and -negative type 1 autoimmune pancreatitis

AIM: To identify clinical and pathological differences between serum immunoglobulin G4 (IgG4)-positive (SIP) and IgG4-negative (SIN) type 1 autoimmune pancreatitis (AIP) in South Korea. METHODS: AIP was diagnosed by the international consensus diagnostic criteria. The medical records and pathology were retrospectively reviewed and IgG4-positive cells were counted in a high power field (HPF). Type I AIP was defined as a high serum level of IgG4or histological finding. SIN type 1 AIP was defined as a histological evidence of type 1 AIP and a normal serum IgG4 level. The clinical and pathological findings were compared between the two groups. The analysis was performed using Student's t test, Fischer's exact test and Mann-Whitney's U test. A P value of < 0.05 was considered statistically significant. As repeated com- parison was made, P values of less than 5% (P < 0.05) were considered significant. RESULTS: Twenty five patients with definite type 1 AIP (19 histologically and six serologically diagnosed cases) were enrolled. The mean tissue IgG4 concentrations were significantly higher in SIP than SIN group (40 cells per HPF vs 18 cells per HPF, P = 0.02). Among eight SIN patients, the tissue IgG4 concentrations were less than 15 cells per HPF in most of cases, except one. The sensitivity of serum IgG4 was 68% (17 SIP and eight SIN AIP). Other organ involvement was more frequent- ly associated with SIP than SIN AIP (59% vs 26%, P = 0.016). However, the relapse rate and diffuse swelling of the pancreas were not associated with serum IgG4 level. The concentrations of IgG4-positive cells per HPF were higher in SIP than SIN AIP (40 vs 18, P = 0.02). CONCLUSION: The sensitivity of serum IgG4 was 68% in type 1 AIP. High serum IgG4 level was associated with other organ involvement and tissue IgG4 concentration but did not affect the relapse rate in type 1 AIP.

Retroperitoneal fibrosis associated with immunoglobulin G4-related disease

Retroperitoneal fibrosis is a rare disease characterized by the development of inflammation and fibrosis in the soft tissues of the retroperitoneum and other abdominal organs.Retroperitoneal fibrosis can be of 2 types:idiopathic and secondary.The recently advocated concept and diagnostic criteria of immunoglobulin G4(IgG4)-related disease,derived from research on autoimmune pancreatitis(AIP),has led to widespread recognition of retroperitoneal fibrosis as a condition caused by IgG4-related disease.We now know that previously diagnosed idiopathic retroperitoneal fibrosis includes IgG4-related disease;however,the actual prevalence is unclear.Conversely,some reports on AIP suggest that retroperitoneal fibrosis is concurrently found in about 10% of IgG4-related disease.Because retroperitoneal fibrosis has no specific symptoms,diagnosis is primarily based on diagnostic imaging(computed tomography and magnetic resonance imaging),which is also useful in evaluating the effect of therapy.Idiopathic retroperitoneal fibrosis can occur at different times with other lesions of IgG4-related disease including AIP.Thus,the IgG4 assay is recommended to diagnose idiopathic retroperitoneal fibrosis.High serum IgG4 levels should be treated and monitored as a symptom of IgG4-related disease.The first line of treatment for retroperitoneal fibrosis is steroid therapy regardless of its cause.For patients with concurrent AIP,i.e.,IgG4-related retroperitoneal fibrosis,the starting dose of steroid is usually 30-40 mg/d.The response to steroid therapy is generally favorable.In most cases,the pancreatic lesion and retroperitoneal fibrosis improve after the initial treatment.However,the epidemiology,treatment for recurring retroperitoneal fibrosis,and long-term prognosis are still largely unknown.Further analysis of such cases and research are necessary.

Immunoglobulin G4-related gastrointestinal diseases, are they immunoglobulin G4-related diseases?

In immunoglobulin G4(IgG4)-related disease(RD),organ enlargement or nodular lesions consisting of abundant infiltration of lymphocytes and IgG4-positive plasma cells and fibrosis are seen in various organs.Although infiltration of many IgG4-positive plasma cells is detected in the gastric and colonic mucosa and major duodenal papilla of patients with autoimmune pancreatitis,it cannot be diagnosed as a gastrointestinal lesion involved in IgG4-RD,because none of the following is observed in these lesions:a mass-like formation;dense fibrosis;or obliterative phlebitis.Based on our review of the literature,there appear to be two types of IgG4-related gastrointestinal disease.One is a gastrointestinal lesion showing marked thickening of the wall of the esophagus and stomach,consisting of dense fibrosis with abundant infiltration of IgG4-positive plasma cells,which usually show submucosal spreading.The other is an IgG4-related pseudotumor occurring in gastrointestinal regions such as the stomach,colon,and major duodenal papilla,showing polypoid or mass-like lesions.Most solitary IgG4-related gastrointestinal lesions that are not associated with other IgG4-RD appear to be difficult to diagnose.It is of utmost importance to rule out malignancy.However,these lesions may respond to steroid therapy.To avoid unnecessary resection,IgG4-related gastrointestinal diseases should be considered in the differential diagnosis.

Biomarkers in autoimmune pancreatitis and immunoglobulin G4-related disease

Solitary organ autoimmune disorders,formerly known as autoimmune pancreatitis(AIP),autoimmune sialadenitis,and autoimmune sclerosing cholangitis,are now considered organ-specific manifestations of systemic immunoglobulin G4-related disease(IgG4-RD).AIP and IgG4-RD are characterized by elevated serum concentration of IgG4 antibody(Ab),accumulation of IgG4-expressing plasmacytes in the affected organs,and involvement of multiple organs.It is well established that enhanced IgG4 Ab responses are a hallmark of AIP and IgG4-RD for diagnosis and monitoring disease activity.However,a significant fraction of patients with AIP and IgG4-RD who develop chronic fibroinflammatory responses have normal serum concentrations of this IgG subtype.In addition,disease flare-up is sometimes seen even in the presence of normalized serum concentrations of IgG4 Ab after successful induction of remission by prednisolone.Therefore,it is necessary to identify new biomarkers based on the understanding of the pathophysiology of AIP and IgG4-RD.Recently,we found that activation of plasmacytoid dendritic cells producing both interferon-α(IFN-α)and interleukin-33(IL-33)mediate murine AIP and human IgG4-RD.More importantly,we provided evidence that serum concentrations of IFN-αand IL-33 could be useful biomarkers for the diagnosis and monitoring of AIP and IgG4-RD activity after induction of remission in these autoimmune disorders.In this Frontier article,we have summarized and discussed biomarkers of AIP and IgG4-RD,including Igs,autoAbs,and cytokines to provide useful information not only for clinicians but also for researchers.

Clinical characteristics and outcome of autoimmune pancreatitis based on serum immunoglobulin G4 level:A single-center,retrospective cohort study

BACKGROUND Autoimmune pancreatitis(AIP)has been linked with elevated immunoglobulin(Ig)G4 levels.The characteristics and outcomes of AIP based on serum markers have not been fully evaluated.AIM To compare clinical features,treatment efficacy,and outcome of AIP based on serum IgG4 levels and analyze predictors of relapse.METHODS A total of 213 patients with AIP were consecutively reviewed in our hospital from 2006 to 2021.According to the serum IgG4 level,all patients were divided into two groups,the abnormal group(n=148)with a high level of IgG4[>2×upper limit of normal(ULN)]and the normal group(n=65).The t-test or Mann-Whitney U test was used to compare continuous variables.Categorical parameters were compared by theχ^(2) test or Fisher’s exact test.Kaplan-Meier curves Zhou GZ et al.Clinical characteristics and outcome of AIP WJG https://www.wjgnet.com 5126 September 21,2023 Volume 29 Issue 35 and log-rank tests were established to assess the cumulative relapse rates.Univariate and multivariate analyses were used to investigate potential risk factors of AIP relapse.RESULTS Compared with the normal group,the abnormal group had a higher average male age(60.3±10.4 vs 56.5±12.9 years,P=0.047);higher level of serum total protein(72.5±7.9 g/L vs 67.2±7.5 g/L,P<0.001),IgG4(1420.5±1110.9 mg/dL vs 252.7±106.6 mg/dL,P<0.001),and IgE(635.6±958.1 IU/mL vs 231.7±352.5 IU/mL,P=0.002);and a lower level of serum complement C3(100.6±36.2 mg/dL vs 119.0±45.7 mg/dL,P=0.050).In addition,a lower number of cases with abnormal pancreatic duct and pancreatic atrophy(23.6%vs 37.9%,P=0.045;1.6%vs 8.6%,P=0.020,respectively)and a higher rate of relapse(17.6%vs 6.2%,P=0.030)were seen in the abnormal group.Multivariate analyses revealed that serum IgG4[(>2×ULN),hazard ratio(HR):3.583;95%confidence interval(CI):1.218–10.545;P=0.020]and IgA(>1×ULN;HR:5.908;95%CI:1.199–29.120;P=0.029)and age>55 years(HR:2.383;95%CI:1.056–5.378;P=0.036)were independent risk factors of relapse.CONCLUSION AIP patients with high IgG4 levels have clinical features including a more active immune system and higher relapse rate.Several factors,such as IgG4 and IgA,are associated with relapse.

Immunoglobulin G4-related kidney diseases: An updated review

This review will encompass definition, pathogenesis, renal clinical manifestations and treatment of immunoglobulin G4-related diseases( IgG4-RDs). IgG4-RD is a recently recognized clinical entity that often involves multiple organs and is characterized by high levels of serum immunoglobulins G4, dense infiltration of IgG4+ cells and storiform fibrosis. Cellular immunity, particularly T-cell mediated immunity, has been implicated in the pathogenesis of IgG4-RDs. The most frequent renal manifestations of IgG4-RD are IgG4-related tubulointerstitial nephritis, membranous glomerulopathy and obstructive nephropathy secondary to urinary tract obstruction due to IgG4-related retroperitoneal fibrosis. IgG4-RD diagnosis should be based on specific histopathological findings, confirmed by tissue immunostaining, typical radiological findings and an appropriate clinical context. The first line treatment is the steroids with two warnings: Steroid resistance and relapse after discontinuation. In the case of steroid resistance, B cell depleting agents as rituximab represent the secondline treatment. In the case of relapse after discontinuation, steroid treatment may be associated with steroid sparing agents. Since the disease has been only recently identified, more prospective, long-term studies are needed to an improved understanding and a more correct and safe treatment.

An aortoduodenal fistula as a complication of immunoglobulin G4-related disease

Most primary aortoduodenal fistulas occur in the presence of an aortic aneurysm,which can be part of immunoglobulin G4(IgG4)-related sclerosing disease.We present a case who underwent endovascular grafting of an aortoduodenal fistula associated with a high serum IgG4 level.A 56-year-old male underwent urgent endovascular reconstruction of an aortoduodenal fistula.The patient received antibiotics and other supportive therapy,and the postoperative course was uneventful,however,elevated levels of serum IgG,IgG4 and C-reactive protein were noted,which normalized after the introduction of steroid therapy.Control computed tomography angiography showed no endoleaks.The primary aortoduodenal fistula may have been associated with IgG4-related sclerosing disease as a possible complication of IgG4-related inflammatory aortic aneurysm.Endovascular grafting of a primary aortoduodenal fistula is an effective and minimally invasive alternative to standard surgical repair.

Immunoglobulin G4-related autoimmune pancreatitis and sialadenitis: A case report

Immunoglobulin G4(Ig G4)-related disease is a rare systemic diseases. A 67-year-old male presented at our institution with mild upper abdominal pain and jaundice for 20 d. Laboratory results revealed high levels of Ig G4(15.4 g/L,range: 0.08-1.4 g/L). Computed tomography(CT) showed significant enlargement of the entire pancreas and a capsule-like low-density rim surrounding the whole pancreas. Positron emission tomography/CT revealed increased uneven metabolism of the entire pancreas. Both magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography showed stenosis of the distal common bile duct and proximal main pancreatic duct,and dilation of the proximal common bile duct and extra- and intra-hepatic bile ducts. He was diagnosed with Ig G4-related autoimmune pancreatitis. The patient was treated with prednisone for 14 mo. The patient responded well to prednisone but upon cessation of the corticosteroid developed enlargement of the submandibular gland. The patient's serum Ig G4 was elevated at 23.9 g/L. It is important to maintain treatment,so the patient was again treated with prednisone and had a good response. Follow-up of Ig G4-related disease is thus necessary.

Successful treatment of tubulointerstitial nephritis in immunoglobulin G4-related disease with rituximab: A case report

BACKGROUND Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated condition that consisted of disorders that share particular clinical,serologic and pathologic properties.The common presentation of disease includes tumor-like swelling of involved organs and the histopathological findings are a lymphoplasmacytic infiltrate enriched with IgG4-positive plasma cells,and a variable degree of fibrosis that has a characteristic "storiform" pattern in biopsy specimens of tumorlike masses.Major presentations of this disease,which often affects more than one organ,include autoimmune pancreatitis,salivary gland disease (sialadenitis),orbital disease and retroperitoneal fibrosis.The steroid treatment is essential for the treatment of the disease however,other immunosuppressive drugs including cyclophosphamide or rituximab could be an option in resistant cases.CASE SUMMARY Herein,we reported a 34-year-old woman whom previously had diagnosed with asthma,rheumatoid arthritis and Sj?gren’s syndrome (SS) referred our nephrology department due to acute kidney failure development at the last rheumatology visit.After kidney biopsy she has been diagnosed with IgG4-RD and tubuluointerstitial nephritis.She had been accepted resistant to steroid,mycophenolate mofetil,methotrexate and azathioprine therapies due to receiving in last two years.She refused to receive cyclophosphamide due to potential gonadotoxicity of the drug.Thus,rituximab therapy was considered.She received 1000 mg infusion,15 d apart and 6 mo later it has been administered same protocol.After one year from the last rituximab dose serum creatinine decreased from 4.4 mg/dL to 1.6 mg/dL,erythrocyte sedimentation rate decreased from 109 mm/h to 13 mm/h [reference range (RR) 0-20],and Creactive protein decreased from 55.6 mg/L to 5 mg/L (RR 0–6).All pathologic lymph nodes and masses were also disappeared.CONCLUSION Patients with IgG4-RD usually misdiagnosed with rheumatologic diseases including systemic lupus erythematous or SS and also they were screened for the presence of malignancy.Rituximab could be an important treatment option in cases with steroid resistant tubulointerstitial nephritis in IgG4-RD.

Clinical characteristics and outcomes of autoimmune pancreatitis based on serum immunoglobulin G4 levels:A single-center,retrospective cohort study

Autoimmune pancreatitis(AIP)is a complex,poorly understood disease gaining increasing attention."Clinical Characteristics and Outcome of AIP Based on Serum IgG4 levels,"investigated AIP with a focus on serum immunoglobulin(Ig)G4 levels.The 213 patients with AIP were classified according to serum IgG4 levels:Abnormal(elevated)and normal.Patients with higher IgG4 levels exhibited a more active immune system and increased relapse rates.Beyond IgG4,the IgA levels and age independently contributed to relapse risk,guiding risk assessment and tailored treatments for better outcomes.However,limitations persist,such as no IgA correlation with IgG4 levels,absent data on autoantibodypositive AIP cases critical for Asian diagnostic criteria,and unexplored relapse rates in high serum IgG AIP by subtype.Genetic factors and family histories were not addressed.As the understanding and referral of seronegative AIPs increase,there's a growing need for commercially available,highly sensitive,and specific autoantibodies to aid in diagnosing individuals with low or absent serum IgG4 levels.

Novel mechanism of hepatobiliary system damage and immunoglobulin G4 elevation caused by Clonorchis sinensis infection

Clonorchis sinensis infection is still a major public health problem.It is estimated that more than 15 million people worldwide are infected,especially in Northeast China,Taiwan,South Korea,and North Vietnam.The detection of Clonorchis sinensis eggs in feces and bile is still the only gold standard for the diagnosis of Clonorchis sinensis infection,and new detection methods are needed to improve the detection rate.After Clonorchis sinensis invades the human body,it mainly parasitizes the hepatobiliary tract.Therefore,it is closely related to hepatobiliary diseases such as cholangitis,bile duct stones,liver fibrosis,and cholangiocarcinoma.The increase in immunoglobulin G4(IgG4)caused by Clonorchis sinensis infection is rare and there are few reports about the relevant mechanism.It may be related to the inflammatory factors interleukin(IL)-4,IL-10,and IL-13 produced by human phagocytes,T cells,B cells,and other immune cells in the process of resisting the invasion of Clonorchis sinensis.However,this finding still needs further clarification and confirmation.This article reviews the epidemiology,clinical manifestations,serology,imaging,pathogenic mechanism,and control measures of Clonorchis sinensis infection to help establish the diagnostic process for Clonorchis sinensis.We report novel mechanisms of IgG4 elevation due to Clonorchis sinensis infection to provide more experience and a theoretical basis for clinical diagnosis and treatment of this infection.

Progressive multi-organ expression of immunoglobulin G4-related disease: A case report

A 63-year-old Caucasian man presented with a cholestatic syndrome, renal failure and arthralgias. A laboratory examination revealed high immunoglobulin G (IgG) and IgG4 levels (5.95 g/L; normal range: 0.08-1.4 g/L), pointing to a diagnosis of systemic IgG4-related disease, with definite radiological evidence of biliary and pancreatic expression, and plausible renal, articular, salivary and lacrimal glands involvement. Due to the rarity of the condition, there are currently no random control trials to point to the optimal therapeutic approach. The patient has been on steroid therapy with the subsequent introduction of azathioprine, with a complete resolution of all symptoms, a rapid reduction to normalization of all blood tests, and a complete regression of the radiological picture. Our experience underlines the complexity of IgG4-related disease and its variable and sometimes progressive presentation, while pointing out the need for a careful and complete assessment for possible multi-organ involvement.

Immunoglobulin G4 associated autoimmune cholangitis and pancreatitis and nivolumab

This letter to editor discussing on the publication on immunoglobulin G4 associated autoimmune cholangitis and pancreatitis following the administration of nivolumab.Concerns on confounding factors are raised and discussed.

Immunoglobulin G4-related disease involving multiple systems:A case report

BACKGROUND Ig G4-related disease(Ig G4-RD),an immune-mediated chronic progressive fibroinflammatory disease,can affect the functions of several organs.Some common characteristics can be observed in different Ig G4-RDs,such as higher prevalence in middle-aged and elderly male patients,raised serum Ig G4 levels,abundant infiltration of Ig G4-positive cells and fibrosis,diffuse or localized swelling of the affected organs,and good response to glucocorticoids treatment.CASE SUMMARY A 72-year-old man complained of left upper abdominal pain 3 mo ago,and he was diagnosed with acute onset of chronic cholecystitis and acute pancreatitis in the local hospital.Pain improved after relevant treatment.Several days ago,his abdominal pain worsened,and he was admitted to our hospital for further treatment.Doppler ultrasound showed that the pancreas presented with sausagelike swelling and the parenchymal echo was diffusely reduced.Gallbladder volume was increased,while the wall was rough and thickened with bilateral signs.Furthermore,the left submandibular gland was enlarged,accompanied with significantly increased blood flow signals.Finally,we found that the adventitia of the abdominal aorta and right iliac artery was thickened locally.Serum Ig G4 was elevated to 12600 mg/L.Therefore,the patient was diagnosed with Ig G4-RD.After treatment with methylprednisolone,he had an uneventful course and was discharged in good condition.CONCLUSION Ig G4-RD can involve almost any organs.Ultrasound has a significant role in timely and accurately diagnosis.

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

BACKGROUND Immunoglobulin G4 related disease(Ig G4-RD)is a fibroinflammatory disease with markedly elevated serum Ig G4 levels and fibrous tissue proliferation,accompanied by numerous plasma cells.Ig G4 related hypertrophic pachymeningitis(Ig G4-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 Ig G4-RD.Moreover,the serum Ig G4 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 Ig G4-RHP is relatively rare and indistinguishable before the operation.Elevated serum Ig G4 levels and imaging examination help in the diagnosis of Ig G4-RHP.Surgery is necessary when lesions progress and patients start to develop cranial nerve function deficit.

Usefulness of ultrasonography to assess the response to steroidal therapy for the rare case of type 2b immunoglobulin G4-related sclerosing cholangitis without pancreatitis:A case report

BACKGROUND A type 2b immunoglobulin G4(IgG4)-related sclerosing cholangitis(SC)without autoimmune pancreatitis is a rare condition with IgG4-SC.While the variety of the imaging modalities have tested its usefulness in diagnosing the IgG4-SC,however,the usage of ultrasonography for the assessment of the response to steroidal therapy on the changes of bile duct wall thickness have not been reported in the condition.Therefore,the information of our recent case and reported cases have been summarized.CASE SUMMARY We report the case of an 82-year-old Japanese man diagnosed with isolated IgG4-related SC based on the increase of serum IgG4,narrowing of the bile duct,its wall thickness,no complication of autoimmune pancreatitis,and IgG4 positive inflammatory cell infiltration to the wall with the fibrotic changes.The cholangiogram revealed type 2b according to the classification.Corticosteroid treatment showed a favorable effect,with the smooth decrease in serum IgG4 and the improvement of the bile duct wall thickness.CONCLUSION As isolated type 2b,IgG4-SC is rare,the images,histological findings,and clinical course of our case will be helpful for physicians to diagnose and treat the new cases appropriately.

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

BACKGROUND Immunoglobulin(Ig)G4-related disease(Ig G4-RD)is an autoimmune disease associated with chronic and progressive inflammation and fibrosis.It is difficult to differentiate Ig G4-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 464μmol/L.The patient was diagnosed with acute renal failure and was started on intermittent hemodialysis.Further tests revealed high serum Ig G4 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 Ig G4-RD.After corticosteroid therapy,his serum creatinine level quickly decreased to near normal levels.CONCLUSION Ig G4-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.