Characteristic findings in images of extra-pancreatic lesions associated with autoimmune pancreatitis

Multisystem diseases in the abdomen and pelvis: imaging manifestations and diagnostic roles of cross-sectional imaging

Systemic diseases, such as IgG4-related disease, sarcoidosis, and amyloidosis, usually involve multiple systems or organs simultaneously or sequentially. The gastrointestinal tract, hepatobiliary system, and genitourinary tract are commonly involved in many multisystem diseases and can also be the first sites with disease involvement. Cross-sectional imaging, such as CT and MR, plays an important role in the diagnosis and management of multisystem diseases by aiding in the evaluation of multiorgan involvement. Here, common imaging features of frequently affected organs are reviewed in multisystem diseases that we often encounter in the abdomen and pelvis, and the diagnostic roles of cross-sectional imaging for these diseases are also discussed.

[IgG4-related disease: A proteiform pathology with frequent chest manifestations]

INTRODUCTION

While IgG4-related disease (IgG4-RD) was initially described in the early 2000s, its polymorphic clinical manifestations were previously reported under different names ; they have in common the presence of IgG4+ oligoclonal plasma cells and fibrosis.

STATE OF THE ART

Ruling out certain differential diagnoses, the diagnosis of IgG4-RD is based on a bundle of clinical, biological and histological features. Chest involvement is variable and can affect the mediastinum, bronchi, parenchyma, pleura and/or, more rarely, bones and (pericardium, aorta, coronary…) vascular structures. The most frequent radiological manifestations are peribronchovascular thickening, mediastinal lymphadenopathy, and nodular or interstitial patterns. Pleural involvement and posterior mediastinal fibrosis are less frequent, while thoracic paravertebral tissue thickening is highly specific. Systemic corticosteroids are the cornerstone of treatment. In case of relapse or as frontline therapy in case of risk factors for relapse and/or poor tolerance of corticosteroids), a steroid-sparing agent (most often rituximab) is added, and biannual maintenance infusions are associated with a lower risk of relapse.

PERSPECTIVES

An international consensus has recently led to the development of classification criteria that should standardize the diagnostic approach and homogenize the enrolment of patients in epidemiological as well as therapeutic studies. Other treatments are also under evaluation, including biologics targeting T2 inflammation, CD-19 (inebilizumab, obexelimab), SLAMF7 (elotuzumab) surface proteins, Bruton's tyrosine kinase, and the JAK/STAT pathway.

CONCLUSIONS

Substantial progress has been made over recent years in understanding IgG4-RD pathophysiology, and personalized patient care seems to be an achievable medium-term goal.

Multimodality pictorial review of IgG4-related disease in the abdomen and pelvis

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a systemic, immune-mediated disease that can affect multiple organs, including the orbits, salivary glands, thyroid gland, lungs, aorta, pancreas, bile ducts, lymph nodes, and retroperitoneum. While timely diagnosis is particularly important given the efficacy of glucocorticoid treatment for IgG4-RD, accurate recognition can prove a challenge given the overlap between the imaging features of this disease and other entities.

PURPOSE

After a review of the epidemiology, pathophysiology, and clinical considerations (including treatment) associated with IgG4-RD, this pictorial review will showcase the variable imaging manifestations of this disease in the abdomen and pelvis. Post-treatment imaging appearance of these entities will be reviewed and mimickers of this disease in the abdomen and pelvis will be presented.

CONCLUSION

The presence of mass-like soft tissue with radiographic characteristics of fibrosis affecting multiple organs should raise suspicion for IgG4-RD, although definite diagnosis can only be made with appropriate clinical, serological, and pathologic data.

Update on respiratory lesions in patients with IgG4-related autoimmune pancreatitis

We previously reported respiratory involvement in 25 patients with autoimmune pancreatitis, a pancreatic manifestation of IgG4-related disease that responds well to glucocorticoid treatment. However, whether all respiratory lesions in patients with autoimmune pancreatitis have genuine respiratory involvement is unclear. This study aimed to update respiratory lesions' clinical and radiological characteristics in patients with autoimmune pancreatitis. We retrospectively reviewed the clinical and radiological data of 74 consecutive patients diagnosed with autoimmune pancreatitis at Shinshu University Hospital and treated with glucocorticoid. Clinical features and chest high-resolution computed tomography findings before and after therapy were reviewed. Fifty-one patients (68.9%) had respiratory lesions. In 65 of the 74 patients, chest high-resolution computed tomography results were evaluated before and after treatment. Patients with IgG4-related disease and respiratory lesions showed significantly higher serum IgG4 levels and hypocomplementemia than those without respiratory lesions; they also had more affected organs. While most abnormal thoracic findings improved, 4 cases of 7 with reticular opacities and all 11 cases with emphysema did not improve. Therefore, these lesions with poor response to glucocorticoid treatment should not be considered due to respiratory involvement of autoimmune pancreatitis based on the current classification criteria for IgG4-related disease. Patients with autoimmune pancreatitis and respiratory lesions exhibited higher disease activity than those without. Most chest high-resolution computed tomography lesions were responsive to glucocorticoid treatment, whereas reticular opacities and emphysema were poorly responsive.

Thoracic manifestations of IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a recently described rare systemic fibroinflammatory disease with an estimated incidence of less than 1 in 100,000 persons per year. The disease can affect virtually any organ and is characterized by unifying histopathological findings. Recently, four subgroups of patients have been characterized: hepatobiliary, head and neck, Mikulicz syndrome and retroperitoneal fibrosis, who illustrate the mainly abdominal and ENT tropism of the disease. Yet, thoracic involvement is not uncommon. It can be detected in up to 30% of patients with systemic IgG4-RD and is the exclusive manifestation of the disease in about 10% of cases. Clinical symptoms are nonspecific and may include dyspnoea, cough or chest pain. Chest CT findings are heterogeneous and primarily include peribronchovascular thickening, nodules, ground-glass opacities and lymphadenopathy. There is no specific diagnostic test for IgG4-RD thoracic involvement, which may mimic malignancy or vasculitis. Therefore, a cautious approach is needed to make an accurate diagnosis: a search for extra-thoracic manifestations, elevated serum IgG4 levels, circulating levels of plasmablasts and pathologic evidence of disease is warranted. Although very suggestive, neither the presence of a polyclonal IgG4 lymphoplasmacytic infiltrate, storiform fibrosis or obliterative phlebitis are sufficient to confirm the histological diagnosis. Steroids are recommended as first-line therapy. Rituximab or disease-modifying antirheumatic drugs may be used in relapsed or rare cases of steroid-refractory disease. In this review, we summarize current knowledge regarding the pathophysiology, epidemiology, diagnostic modalities (clinical-biological-imaging-histopathology) and treatment of IgG4-RD thoracic involvement.

Diagnostic value of imaging examination in autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis mediated by autoimmunity factors. It can be divided into two categories according to pathological characteristics: Lymphoplasmacytic sclerosing pancreatitis and idiopathic duct-centric pancreatitis. In the clinical setting, the imaging manifestations of some AIP cases are atypical, so it is difficult to distinguish it from general pancreatitis, pancreatic ductal adenocarcinoma, lymphoma, and other malignant disorders. Most importantly, the treatment for and prognosis of these diseases are different. Therefore, a timely correct imaging diagnosis of AIP is key for AIP patients. After that, clinicians can take appropriate treatment measures for those patients, which is helpful for the prognosis of AIP.

Immunoglobulin G4-related disease diagnosed by prostate biopsy: a case report

Background

Immunoglobulin G4-related disease is characterized by swelling of various organs throughout the body and nodules/hypertrophic lesions. However, its cause remains unknown. We report a case of immunoglobulin G4-related disease that was diagnosed based on the histopathological findings of prostate biopsy.

Case presentation

A 72-year-old Japanese man had been treated by a nearby doctor for hypertension, but subsequently developed lower urinary tract symptoms and was prescribed an α1 blocker for 1 year. However, the patient was subsequently referred to our department because his symptoms did not improve. Prostate-specific antigen was 1.258 ng/ml; however, the nodule was palpable in the right lobe on digital rectal examination, and magnetic resonance imaging suggested Prostate Imaging and Reporting and Data System category 3. Therefore, transrectal prostate needle biopsy (12 locations) under ultrasound was performed. Histopathological examination revealed no malignant findings, although infiltration of lymphocytes and plasma cells, and partial fibrosis were observed. No remarkable findings of obstructive phlebitis were observed. Immunoglobulin G4-related disease was suspected, and immunoglobulin and immunoglobulin G4 immunostaining was performed. Immunoglobulin G4 positive plasma cells were observed in a wide range, immunoglobulin G4 positive cells were noted at > 10 per high-power field, and the immunoglobulin G4 positive/immunoglobulin G positive cell ratio was > 40%. Serum immunoglobulin G4 levels were high at 1600 mg/dl. Enhanced abdominal computed tomography findings suggested periaortitis. Additionally, multiple lymphadenopathies were observed around the abdominal aorta. The patient was accordingly diagnosed with immunoglobulin G4-related disease definite, diagnosis group (definite). We proposed steroid treatment for periaortic soft tissue lesions and lower urinary tract symptoms; however, the patient was refused treatment. A computed tomography scan 6 months after diagnosis revealed no changes in the soft tissue lesions around the aorta. Follow-up computed tomography examinations will be performed every 6 months.

Conclusion

If immunoglobulin G4-related disease is suspected and a highly invasive examination is required for histopathological diagnosis, this can be performed by a relatively minimally invasive prostate biopsy for patients with lower urinary tract symptoms. Further evidence is needed to choose an optimal candidate for prostate biopsy for lower urinary tract symptoms patients with suspicion of immunoglobulin G4-related disease. For patients with lower urinary tract symptoms with immunoglobulin G4-related disease or a history, performing a prostate biopsy may avoid unnecessary treatment. However, if steroid therapy is ineffective, surgical treatment should be considered.

American College of Rheumatology and the European League Against Rheumatism classification criteria for IgG4-related disease: an update for radiologists

IgG4-related disease (IgG4-RD) is an immune-mediated, multiorgan, chronic inflammatory disease. The three-step classification criteria proposed in 2019 by the American College of Rheumatology and the European League Against Rheumatism (ACR/EULAR) encompass a wide range of clinical, radiological, serological, and histopathological findings. The ACR/EULAR proposed a three-step classification process, i.e., entry step, exclusion step, and scoring system. Radiologists need to know that the radiological findings observed in the five domains of the lacrimal and salivary glands, chest, pancreas and biliary ducts, kidney, and retroperitoneum are independently weighted with different points in the scoring system. A total score < 20 points indicates that the patient should not be classified as having IgG4-RD; conversely, a total score ≥ 20 points indicates that the patient should be classified as having IgG4-RD. In this review, the 2019 ACR/EULAR classification criteria are discussed, focusing on the interpretation of each radiological item, with the aim of applying them to the diagnosis of IgG4-RD in clinical practice.

Usefulness of renal diffusion-weighted magnetic resonance imaging for early diagnosis of tubulointerstitial nephritis and uveitis (TINU) syndrome

A teenage girl presented with fever after aspirin use. Examination revealed no organ-specific symptoms. The serum creatinine level and urine analysis findings were normal. The drug lymphocyte stimulation test was positive for aspirin. Diffusion-weighted magnetic resonance imaging (DW-MRI) revealed hyperintensity in both kidneys although serum creatinine was only mildly elevated. A subsequent kidney biopsy confirmed acute interstitial nephritis (AIN). She later developed uveitis and the final diagnosis was tubulointerstitial nephritis and uveitis (TINU) syndrome, possibly triggered by aspirin, requiring systemic and topical corticosteroid therapies. TINU syndrome should be considered in young patients with fever of unknown origin and a history of nonsteroidal anti-inflammatory drug use. This is the first reported case suggesting the usefulness of DW-MRI, which is safe for children without exposure to ionising radiation, in detecting early-stage AIN before apparent kidney impairment.

Amendment of the Japanese consensus guidelines for autoimmune pancreatitis, 2020

In response to the latest knowledge and the amendment of the Japanese diagnostic criteria for autoimmune pancreatitis (AIP) in 2018, the Japanese consensus guidelines for managing AIP in 2013 were required to be revised. Three committees [the professional committee for developing clinical questions (CQs) and statements by Japanese specialists; the expert panelist committee for rating statements by the modified Delphi method; and the evaluating committee of moderators] were organized. Twenty specialists in AIP extracted the specific clinical statements from a total of 5218 articles (1963-2019) from a search in PubMed and the Cochrane Library. The professional committee made 14, 9, 5, and 11 CQs and statements for the current concept and diagnosis, extra-pancreatic lesions, differential diagnosis, and treatment, respectively. The expert panelists regarded the statements as valid after a two-round modified Delphi approach with individually rating these clinical statements, in which a clinical statement receiving a median score greater than 7 on a 9-point scale from the panel was regarded as valid. After evaluation by the moderators, the amendment of the Japanese consensus guidelines for AIP has been proposed in 2020.

Thoracic involvement and imaging patterns in IgG4-related disease

OBJECTIVE

Immunoglobulin G4-related disease (IgG4-RD) is a rare orphan disease. Lung, pleura, pericardium, mediastinum, aorta and lymph node involvement has been reported with variable frequency and mostly in Asian studies. The objective of this study was to describe thoracic involvement assessed by high-resolution thoracic computed tomography (CT) in Caucasian patients with IgG4-RD.

METHODS

Thoracic CT scans before treatment were retrospectively collected through the French case registry of IgG4-RD and a single tertiary referral centre. CT scans were reviewed by two experts in thoracic imagery blinded from clinical data.

RESULTS

48 IgG4-RD patients with thoracic involvement were analysed. All had American College of Rheumatology/European League Against Rheumatism classification scores ≥20 and comprehensive diagnostic criteria for IgG4-RD. CT scan findings showed heterogeneous lesions. Seven patterns were observed: peribronchovascular involvement (56%), lymph node enlargement (31%), nodular disease (25%), interstitial disease (25%), ground-glass opacities (10%), pleural disease (8%) and retromediastinal fibrosis (4%). In 37% of cases two or more patterns were associated. Asthma was significantly associated with peribronchovascular involvement (p=0.04). Among eight patients evaluated by CT scan before and after treatments, only two patients with interstitial disease displayed no improvement.

CONCLUSION

Thoracic involvement of IgG4-RD is heterogeneous and likely underestimated. The main thoracic CT scan patterns are peribronchovascular thickening and thoracic lymph nodes.

Role of transabdominal ultrasound in the diagnosis of autoimmune pancreatitis

The most important thing in the diagnosis of autoimmune pancreatitis (AIP) is to suspect the possibility of AIP. In the acute phase, diffuse pancreatic enlargement is a highly specific finding of AIP compared to focal enlargement. Though the sensitivity is low, high-frequency transducers can detect the capsule-like rim sign and penetrating duct sign. Those findings are characteristic of AIP and useful for differential diagnosis with pancreatic carcinoma. In focal AIP, both contrast-enhanced US showing iso/hypervascularity and elastography showing increased stiffness not only in the focal enlargement but also in the surrounding parenchyma are also useful for differential diagnosis. Furthermore, changes over time after the two-week steroid trial, such as resolution or measurable reduction in parenchymal enlargement and a decrease in the mean shear-wave velocity on elastography, are also cardinal features of AIP. Since AIP is a pancreatic manifestation in immunoglobulin G4-related disease, evaluation of other organs, including the biliary tract and salivary glands, is particularly useful in focal AIP. A characteristic US finding of bile ducts is three-layered (high-low-high pattern) wall thickening with a markedly thickened middle layer. US can also detect wall thickening of bile ducts, which show no abnormalities on cholangiography. These findings are useful for differential diagnosis with cholangiocarcinoma. Multiple hypoechoic areas in submandibular glands are characteristic US findings of sialadenitis in type 1 AIP, and the sensitivity is higher than that of physical examination. US can further contribute to the diagnosis of AIP by employing elastography and contrast-enhanced US in addition to high-frequency transducers.

Immunoglobulin G4-related disease: case report and literature review

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a rare and chronic progressive clinical entity, characterized by elevated serum IgG4 along with tissue infiltration by IgG4 + plasma cells. It is an immune-mediated fibro-inflammatory condition that can affect virtually any organ and tissue. IgG4-related lung disease (IgG4-RLD) occupies 14% of all IgG4-RD, with nonspecific symptoms and various abnormal radiographic patterns. Published data on IgG4-related hypertrophic pachymeningitis (IgG4-RHP), an increasingly recognized central nervous system manifestation of IgG4-RD, is also limited. Both lung and cranial dura involvement have not yet been reported until now. We further entail a review of the literature on the clinicopathologic features and differential diagnosis of this uncommon disease. We herein report an interesting case of a 70-year-old male patient admitted due to headache and fever. A magnetic resonance imaging (MRI) of the brain revealed extensive dural thickening with marked enhancement. Chest computed tomography (CT) scan showed nodular or mass-like consolidation and focal interstitial change. Thoracoscopic lung biopsy and lumbar puncture were conducted. After careful histopathological observation and consideration of alternative differential diagnoses, he was diagnosed with IgG4-related disease with lung and cranial dural involvement based upon significant elevation of serum and cerebrospinal fluid (CSF) IgG4 concentration. The patient was started on oral prednisolone 60 mg/day (1.0 mg/kg/day) for 14 days, and a tapering dose of 5 mg every 2 weeks followed by maintenance therapy at low dose for 3 months. His clinical manifestations, and serologic and imaging findings improved with steroid treatment. Currently, the patient remains well without disease progression. IgG4-RD should be considered as a differential when diagnosing other similar multisystemic lesions. Clinical examination, careful histological observation, and immunostaining for appropriate markers are essential in establishing the diagnosis. Clinicians should become familiar with this alternative differential diagnosis.

Neuroimaging findings in rheumatologic disorders

Patients with rheumatological diseases may present with neurological manifestations of peripheral and/or central nervous system (CNS). Symptoms may be related to underlying rheumatological disease or CNS effects of immune-modulating drugs. Early diagnosis and therapy may help prevent serious complications. Magnetic resonance imaging (MRI), given its excellent soft tissue details, is the preferred imaging modality when evaluating patients with rheumatological disease and suspected CNS involvement. We present a review of the neuroimaging manifestations of various rheumatic diseases with emphasis on the imaging findings on MRI.

Immunoglobulin G4-related systemic disease: mesenteric and peritoneal involvement with radiopathological correlation and differential diagnoses

Since its first introduction in 2003 by Kamisawa et al., IgG4-related disease has gained wide interest in the imaging community, and several manuscripts have been published regarding its imaging features. In addition to initial observations in the pancreaticobiliary system, it is now well known that the disease may involve every organ system in the body. There is not much information in the imaging literature about the involvement of mesentery, omentum, and peritoneum in this disease. This article aims to provide more information about the imaging findings of IgG4-related disease regarding these areas by making radiopathological correlations and discussing the possible differential diagnoses.

Clinical features and relapse risks of IgG4-related ophthalmic disease: a single-center experience in China

Background

IgG4-related ophthalmic disease (IgG4-ROD) is one of the phenotypes of IgG4-related disease (IgG4-RD), and its lesions are mainly located in the ocular. Currently, there are few studies on IgG4-ROD and no study has compared the phenotypic differences between IgG4-ROD and non IgG4-ROD (nIgG4-ROD). Thus, it is difficult to establish the optimal treatment strategy for IgG4-ROD. The aim of this study was to identify the disparities between the two groups and to clarify the risk factors for IgG4-ROD relapse.

Methods

434 IgG4-RD patients met comprehensive diagnostic criteria and diagnosed at Peking University People’s Hospital between January 2009 and January 2020 were recruited in this study. Patients were divided into IgG4-ROD and nIgG4-ROD group according to the ophthalmic involvement. Demographic, clinical, and laboratory data of two groups were collected and compared. Cox regression analysis was used to identify the independent risk factors for IgG4-ROD relapse.

Results

255 IgG4-ROD patients were identified in this study. IgG4-ROD group had almost equal sex ratio, younger age of disease onset and diagnosis comparing with nIgG4-ROD patients. As compared to nIgG4-ROD group, higher percentage of IgG4-ROD patients met the 2019 American College of Rheumatology/European League Against Rheumatism classification criteria (AECC) for IgG4-RD; moreover, IgG4-ROD patients had higher AECC scores and IgG4-RD responder index (RI). Allergic diseases and multiorgan involvement were more common in IgG4-ROD group. IgG4-ROD was frequently associated with salivary gland, paranasal sinus, lung, and lymph node involvement, while retroperitoneal fibrosis and biliary system lesions were more common in nIgG4-ROD. IgG4-ROD patients had higher serum IgG4 levels, IgG4/IgG ratio, IgE levels, and lower CRP levels. The initial glucocorticoid plus immunosuppressant was a protective factor for IgG4-ROD relapse. IgG4-ROD patients treated with initial glucocorticoid plus immunosuppressant had longer relapse-free survival time than patients treated with initial glucocorticoid monotherapy.

Conclusions

IgG4-ROD patients had distinctive clinical features compared with nIgG4-ROD patients. The initial glucocorticoid plus immunosuppressant was a protective factor for IgG4-ROD relapse, which could prolong the relapse-free survival time of IgG4-ROD patients. These findings may have important implications for understanding and management of IgG4-ROD.

Autoimmune pancreatitis: Current perspectives

Over the last two decades, our knowledge and understanding regarding the pathogenesis and biology of autoimmune pancreatitis (AIP) have improved tremendously. Type 1 AIP or IgG4-related pancreatitis (IgG4-RP) is now believed to be the prototype of the multisystemic IgG4-related disease. In view of clinical features like obstructive jaundice and mass-forming lesions in the pancreas in elderly men, type 1 AIP often mimics pancreatic cancer. IgG4-related sclerosing cholangitis concomitantly involving the extrahepatic and intrahepatic biliary tree is the most common extrapancreatic involvement seen in up to 80% of these patients, which needs to distinguish from cholangiocarcinoma. Histology is characterised by lymphoplasmacytic inflammation, abundant IgG4 positive plasma cell infiltration, storiform fibrosis and obliterative phlebitis. Apart from histology, high serum IgG4 levels, pancreatic parenchymal and duct imaging findings and other organ involvement aid in diagnosis especially in cases where definitive histology is not evident. Also, these parameters lay the foundation of various diagnostic criteria proposed over last few years. On the contrary, histology alone is the mainstay for establishing diagnosis of idiopathic duct-centric pancreatitis (IDCP) as it lacks any specific serological marker or imaging. Since both types of AIP respond dramatically to corticosteroid treatment, a biopsy is crucial to establish the preoperative diagnosis and to exclude malignancy so as to avoid unnecessary surgery. This review discusses the morphologic spectrum, treatment and prognosis of IgG4-RP and IDCP with an emphasis on approach to diagnosis with relevant histologic features, differential diagnoses and the challenges faced during biopsy interpretation.

Long-term clinical course and outcomes of immunoglobulin G4-related lung disease

Background

Immunoglobulin G4-related lung disease (IgG4-RLD) is the pulmonary manifestation of a systemic fibroinflammatory disease characterized by lymphoplasmacytic infiltration with an abundance of IgG4-positive plasma cells. Long-term clinical course and outcomes of IgG4-RLD remain unclear. We aimed to identify clinical characteristics, treatment outcomes, and longitudinal pulmonary function changes in patients with IgG4-RLD according to the radiologic classification.

Methods

Chest computed tomography findings of 37 subjects were classified into five subtypes: solid nodular, bronchovascular, alveolar interstitial, round ground glass opacity, and alveolar consolidative. Radiologic treatment outcomes and longitudinal pulmonary function changes were compared among the different radiologic subtypes.

Results

The mean age of the subjects was 55.6 years, and 78.4% were male. Among the five radiologic subtypes, alveolar consolidative and solid nodular type were most common, accounting for approximately 29.7% each of the total cases. Prednisone with or without azathioprine was administered to 31 patients (median treatment duration 14 months). In the treated patients, serial images showed complete response or partial response in 77.4%. However, relapse was documented in 25.0% of those who showed complete or partial response. In patients whose longitudinal lung function data were available (n = 20), the lung function was found to be stable during follow-up. Alveolar consolidative type showed the highest complete response rate, whereas alveolar interstitial type showed the lowest response rate, either complete or partial.

Conclusions

Most patients showed a favorable outcome with regards to radiologic improvement and maintenance of pulmonary function; however, the response differed according to the radiologic subtype.

Autoimmune pancreatitis - An ongoing challenge

Autoimmune pancreatitis is a rare form of chronic pancreatitis. The first descriptions of the disease date back to the 1990s. Etiology is multifactorial, with the use of genetic, environmental and complex immunological mechanisms. It is classified into two subtypes. Type 1 is part of a group of diseases called IgG4-related disease. Clinically is autoimmune pancreatitis manifested by icterus and abdominal discomfort. It can rarely present as acute pancreatitis. There is also a completely asymptomatic form of the disease. The diagnosis is based on abnormalities in histology, imaging methods, serology, the involvement of other organs in relation to IgG4-related disease, and a significant positive response to corticosteroid therapy. Differential diagnosis between the focal form of autoimmune pancreatitis and pancreatic cancer can be complicated, with endosonography playing an important role. In the treatment, we use corticosteroids and other immunosuppressants including biological therapy. Patients with the asymptomatic disease should also be treated to prevent late complications and exocrine and endocrine insufficiency. In addition to drug treatment, endoscopic and/or surgical treatment may be necessary. Even after recovery, the disease can relapse. The relationship between autoimmune pancreatitis and malignancies has not been clearly confirmed. The goal of this review is to provide a comprehensive look at autoimmune pancreatitis and translate latest scientific knowledge into clinical practice.

Clinical and imaging findings suggestive of histopathological immunoglobulin G4-related disease: a single-center retrospective study

OBJECTIVE

To investigate the clinical and imaging features predicting the histopathological diagnosis of immunoglobulin G4 (IgG4)-related disease (IgG4RD) in patients with suspected IgG4RD on computed tomography (CT).

METHODS

We retrospectively reviewed the medical records of 178 patients with CT findings suspicious of IgG4RD from January 2015 to December 2017. Patients who underwent tissue biopsy were included to evaluate the association between patient characteristics and histopathological diagnosis of IgG4RD. The histopathological diagnosis was classified into IgG4RD and non-IgG4RD. Clinical, laboratory, and imaging features were compared between patients with IgG4RD and non-IgG4RD, and logistic regression analysis was performed to identify the predictors for histopathologically confirmed IgG4RD.

RESULTS

Of the 103 patients with histopathologically proven diseases, 46 and 57 patients were classified as IgG4RD and non-IgG4RD, respectively. The median age was 64 years; 65% of patients were male. There were significant differences in sex (P = 0.035), fever (P = 0.039), serum IgG4 level (P < 0.001), renal involvement (P = 0.036), lacrimal or salivary glands involvement (P = 0.050), swelling pattern on CT (P = 0.001), and positron emission tomography (PET)-CT findings (P < 0.001) between patients with IgG4RD and non-IgG4RD. Multivariate analysis revealed elevated IgG4 level > 135 mg/dL (odds ratio [OR] = 5.418, P < 0.001), kidney involvement (OR = 6.170, P = 0.044), and the swelling feature on CT (OR = 4.301, P = 0.012) to be independent factors for histopathological diagnosis of IgG4RD.

CONCLUSION

This study suggests that elevated IgG4 level, renal involvement, and swelling pattern on CT are associated with histopathological diagnosis of IgG4RD. The clinical and imaging features might help to decide further evaluation in patients with clinically suspected IgG4RD. Key Points • Computed tomography (CT) is not sufficient to discriminate between IgG4-related disease (IgG4RD) and non-IgG4RD conditions. • Histopathological diagnosis of IgG4RD is associated with elevated IgG4 level, renal involvement, and swelling pattern on CT. • Positron emission tomography-CT may be a useful diagnostic tool in patients with clinically suspected IgG4RD. >.

Lung nodules and IgG4 related disease: a single-center based experience

BACKGROUND

This study was undertaken in an attempt to characterize the frequency and clinical features of lung nodules in IgG4 related disease (IgG4-RD) patients as an insight for help with the diagnosis of lung nodules.

METHODS

A retrospective study was carried out in West China Hospital, Sichuan University from January 2012 to December 2018, 89 patients with definite IgG4-RD were enrolled.

RESULTS

Fifty of 89 patients with definite IgG4-RD had radiologically confirmed lung nodules, 6 of whom were diagnosed with definite IgG4 related lung disease. Lung nodules detected in more than 40 patients were small and solid, always with regular margins. Multiple (41/50) and bilateral (34/50) distributions was also a major characteristic of these lung nodules. Lobulation and speculation were simultaneously detected in 3 patients, including 2 patients combined with pleural indentation. Calcification of nodules was detected in only one patient. Thirty-seven patients also had additional radiological abnormalities of lungs, including ground-glass opacity (21/50), thickening of pleura (9/50), thickening of interlobular septa (4/50), thickening of bronchial wall (3/50), pleural effusion (4/50), mass (3/50), interstitial changes (5/50), and mediastinal or hilar lymphadenopathy (32/50). Most patients (44/50) were treated with glucocorticoids alone or combined with immunosuppressive agents. Sixteen patients received a re-examination by chest computed tomography (CT) scan after treatment, 10 of whom showed a decrease in the size and/or the number of nodules.

CONCLUSIONS

The incidence of lung nodules in IgG4-RD patients can be high. For an IgG4-RD patient with lung nodules, the possibility that the lung nodules related to IgG4-RLD is high. It is hard to differentiate IgG4 related lung nodules from other lung diseases, in particular, lung cancer. Radiological characteristics and positive responses to glucocorticoids and immunosuppressive agents can help with the differential diagnosis. For these patients, regular follow-up is also important.

IgG4-related disease in the abdomen and pelvis: atypical findings, pitfalls, and mimics

IgG4-related disease (IgG4-RD) is a systemic, autoimmune, fibroinflammatory disease that can cause multi-organ damage. Although there have been many trials and studies since its recognition in 2003, there is still much that is unknown. Furthermore, IgG4-RD can affect any organ in the body and often has many mimics and alternative diagnoses, which can make for a challenging workup. Imaging plays a substantial role in the diagnosis of IgG4-RD and is often the first occasion where IgG4-RD comes into consideration. Thus, knowledge about the imaging findings of various manifestations of IgG4-RD can aid in the diagnosis and have a significant impact on patient management. In this article, we review the wide array of imaging findings, both typical and atypical, as well as possible mimics of IgG4-RD in the abdomen and pelvis.

Non-tuberculous, adenosine deaminase-positive lymphocytic pleural effusion: Consider immunoglobulin G4-related disease

Objective:

Immunoglobulin G4-related disease (IgG4-RD) is a recently described systemic disorder. Pleural effusion is considered an uncommon manifestation of the disease. We describe a case series of patients with IgG4-RD and clinically significant pleural effusions.

Methods:

A retrospective analysis of patients with histologically proven IgG4-RD treated for pleural effusion in our clinic.

Results:

We identified 4 male patients with pleural effusion caused by IgG4-RD. The effusions were lymphocytic exudates, with especially high protein concentrations. All patients had hyperglobulinemia, elevated serum immunoglobulin G (IgG) levels and elevated levels subclasses IgG1 and IgG4. In two patients, levels of adenosine deaminase (ADA) were measured in the effusion and were elevated (309 and 108 IU/L). Tuberculosis was excluded in both cases by pleural biopsy. Involvement of other organs by IgG4-RD was the rule, especially thoracic lymphadenopathy which was prominent in all patients. In all cases, effusion responded to corticosteroids therapy. One patient developed radiological findings compatible with rounded atelectasis during remission.

Conclusions:

IgG4-RD may cause an ADA-positive, lymphocytic exudate with a high protein concentration, characteristics resembling tuberculous effusion. Thoracic lymphadenopathy, hyperglobulinemia, and an increased total IgG, IgG1, IgG4 may suggest the diagnosis. Not previously described, IgG4-RD pleural inflammation may result in rounded atelectasis. (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (2): 225-230)

Clinical and imaging features of IgG4-related kidney disease

PURPOSE

To assess the clinical and imaging features of IgG4-RKD for understanding and diagnosis of this disease.

METHODS

CT and MR images of 34 patients with IgG4-RKD were retrospectively analyzed by two radiologists in consensus.

RESULTS

The serum IgG4 level was found being increased in all patients. Renal involvement was bilateral (24/34, 70.6%) or unilateral (10/34,29.4%), multiple (29/34, 85.3%) or solitary (5/34, 14.7%). The lesions were wedge-shaped (21) or mass-like (4) in the renal parenchyma, whereas diffusely decreased renal density was noted in 2 patients. All lesions showed progressive contrast enhancement. The 4 mass-like lesions were misdiagnosed as renal malignancy. In 15 patients with follow-up imaging examinations, the number and size of renal lesions decreased after oral hormone treatment. The serum IgG4 levels were significantly decreased after therapy in all patients.

CONCLUSION

IgG4-RKD has various imaging appearances. Although the mass-like appearance mimics renal malignancy in some patients, progressive contrast enhancement in the lesion with elevated serum IgG4 suggests IgG4-RKD.

CT Findings of Upper Urinary Tract Lesions in IgG4-Related Disease: Comparison With Urothelial Carcinoma

OBJECTIVE. IgG4-related disease is characterized by extensive infiltration of IgG4-positive plasma cells and fibrosis in various organs. The objective of this study is to investigate CT findings of IgG4-related lesions involving the upper urinary tract and compare them with those of urothelial carcinomas. MATERIALS AND METHODS. This study reviewed pretreatment CT images of 13 consecutive patients with IgG4-related disease with upper urinary tract lesions and 80 consecutive patients with urothelial carcinomas. The findings assessed were laterality, location, growth pattern, margins, internal structure, presence of calcification and lipid component, enhancement pattern, and extraurinary findings. RESULTS. Bilaterality (p < 0.0001), an extramural growth pattern (p < 0.0001), a greater number of affected segments (p = 0.04), and a gradual dynamic enhancement pattern (p < 0.001) were significantly more frequent in patients with IgG4-related disease. With regard to extraurinary findings, paraaortic fat stranding (p = 0.03), presacral fat stranding (p < 0.001), fat stranding of the pelvic walls (p < 0.001), and aortic involvement (p < 0.001) were seen more frequently in patients with IgG4-related disease; on the other hand, there was no statistically significant difference in terms of frequency of pancreatic involvement. Hydronephrosis and renal involvement were seen more frequently in patients with urothelial carcinoma, although the difference was not statistically significant. CONCLUSION. CT findings suggestive of IgG4-related upper urinary tract lesions in comparison with urothelial carcinoma are bilateral and have a longer urinary tract involvement and exhibit an extramural growth pattern, ill-defined margins, a gradual enhancement pattern, aortic involvement, and fat stranding in the paraaortic, presacral, or pelvic wall areas.

Differentiation of focal autoimmune pancreatitis from pancreatic ductal adenocarcinoma

Autoimmune pancreatitis (AIP) is an inflammatory process of the pancreas that occurs most commonly in elderly males and clinically can mimic pancreatic adenocarcinoma and present with jaundice, weight loss, and abdominal pain. Mass-forming lesions in the pancreas are seen in the focal form of AIP and both clinical and imaging findings can overlap those of pancreatic cancer. The accurate distinction of AIP from pancreatic cancer is of utmost importance as it means avoiding unnecessary surgery in AIP cases or inaccurate steroid treatment in patients with pancreatic cancer. Imaging concomitantly with serological examinations (IgG4 and Ca 19-9) plays an important role in the distinction between these entities. Characteristic extra-pancreatic manifestations as well as favorable good response to treatment with steroids are characteristic of AIP. This paper will review current diagnostic parameters useful in differentiating between focal AIP and pancreatic adenocarcinoma.

Diagnostic imaging guide for autoimmune pancreatitis

The International Consensus Diagnosis Criteria for autoimmune pancreatitis (AIP) has been published internationally for the diagnosis of AIP. However, since the revisions in 2006 and 2011, the Clinical Diagnostic Criteria for Autoimmune Pancreatitis 2018 have been published. The criteria were revised based the Clinical Diagnostic Criteria 2011, and included descriptions of characteristic imaging findings such as (1) pancreatic enlargement and (2) distinctive narrowing of the main pancreatic duct. In addition, pancreatic duct images obtained by magnetic resonance cholangiopancreatography as well as conventional endoscopic retrograde pancreatography were newly adopted. The guideline explains some characteristic imaging findings, but does not contain descriptions of the imaging methods, such as detailed imaging parameters and optimal timings of dynamic contrast-enhanced computed tomography/magnetic resonance imaging. It is a matter of concern that imaging methods can vary from hospital to hospital. Although other characteristic findings have been reported, these findings were not described in the guideline. The present paper describes the imaging methods for obtaining optimal images and the characteristic imaging findings with the aim of standardizing image quality and improving diagnostic accuracy when radiologists diagnose AIP in actual clinical settings.

IgG4-related disease in the differential diagnosis of lung nodules

IgG4-related disease is an evolving entity of immune-mediated origin. We report a case of IgG4-related disease mimicking lung cancer with pleural dissemination. A 76-year-old male non-smoker was admitted to our hospital because of chest X-ray abnormality. Chest computed tomography scan showed a lung nodule measuring 26 × 14 mm with tiny nodules on the adjacent pleural surface. Wedge resection by video-assisted thoracoscopic surgery (VATS) was performed to aid diagnosis. Pathological findings of the nodule consisted of lymphoid follicular hyperplasia with lymphoplasmacytic infiltrate, fibrosis, and obstructive vasculitis. Focal and scattered thickening of the pleura with lymphoplasmacytic infiltrate was also observed. The IgG4/IgG ratio in the most prominent area exceeded 80%. Thus, we made a diagnosis of IgG4-related lung and pleural disease. To our knowledge, there has been no report of IgG4-related lung disease mimicking lung cancer with pleural dissemination.

A comparison of the features of fluorine-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) between IgG4-related disease with bilateral hilar lymphadenopathy and sarcoidosis

We aimed to show the differentiation of the degree and distribution on Fluorine-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) between patients with immunoglobulin G4-related disease (IgG4-RD) and sarcoidosis, though both diseases frequently show bilateral hilar lymphadenopathy (BHL). The clinical records were retrospectively reviewed in 25 patients with IgG4-RD with BHL and 15 patients with sarcoidosis (stage I–II) diagnosed at Shinshu University Hospital. All patients underwent FDG-PET at Aizawa Hospital from January 2004 to December 2015. The FDG accumulation pattern and maximum standardized uptake value (SUVmax) of the hilar lymph nodes were compared between the two groups. The IgG4-RD group (21 men; median age 69 years) showed a significant male predominance and older age compared with the sarcoidosis group (3 men, median age 55.4 years). The IgG4-RD group showed a significantly higher incidence of FDG accumulation in the lachrymal gland, submandibular gland, pancreas, prostate and periurethral and periarterial regions compared with the sarcoidosis group. In contrast, the sarcoidosis group showed a significantly higher incidence of FDG accumulation in the supraclavicular and abdominal lymph nodes, muscle and soft tissues compared with the IgG4-RD group. Furthermore, the SUVmax of the hilar lymph nodes was significantly higher in the sarcoidosis group (median 7.20) than in the IgG4-RD group (median 4.20, p=0.002). In conclusion, significant differences were observed in the FDG accumulation patterns and SUVmax values of the hilar lymph nodes between IgG4-RD with BHL and sarcoidosis, although both diseases develop through the lymphatic routes of the lungs and are frequently associated with BHL.

IgG4-related pleural disease in a patient with a history of unknown origin acute pancreatitis: a case report and review of the literature

Immunoglobulin G4-related disease is a rare autoimmune systemic disease with the capability of involving every organ. The disease is microscopically defined by a diffuse tissular inflammation with an infiltration of IgG4 positive plasma cells in the affected organs. IgG4 disease has an increasing incidence in the last few years with a growing interest in its pathophysiology still misunderstood to date. Despite the growing recognition of this pathology, the literature still does not allow to propose a simple diagnostic algorithm. In this article, we present a case of a 56-year-old man with a history of unknown etiology acute pancreatitis and a unilateral pleural effusion.

An update on IgG4-related lung disease

IgG4-related disease (IgG4-RD) is an autoimmune disorder characterized by substantial infiltration of plasma cells with IgG4 in target organs. Lung manifestations predominantly present as inflammatory pseudotumor, interstitial pneumonitis, organizing pneumonia, and lymphomatoid granulomatosis. There is no specific diagnostic test for IgG4-related lung disease (IgG4-RLD), and excluding diseases that mimic IgG4-RLD is important. Corticosteroids with or without disease-modifying anti-rheumatic drugs are recommended for treatment. The long-term prognosis of IgG4-RLD remains unknown. In this review, we summarized the current diagnostic algorithms and discussed potential biomarkers for future investigation.

Immunoglobulin G4-related disease complicated with vascular lesions: CT findings in 21 patients

PURPOSE

We aimed to analyze multislice computed tomography (MSCT) imaging features of vasculitis in immunoglobulin G4-related disease (IgG4-RD).

METHODS

In this retrospective study, we diagnosed 21 definite or possible IgG4-RD patients (71.4% male; mean age, 52.1±4.5 years) with vasculitis by MSCT and pathologic examination. The clinical background, laboratory analysis, pathologic results, CT images, and response to therapy were assessed and analyzed.

RESULTS

Under enhanced MSCT, 50 vasculitic lesions were identified and were divided into five types (types A-E) according to the CT findings on the basis of luminal changes. There were more vasculitic lesions observed below the diaphragm (n=30) than above it (n=20). Aneurysms and aneurysmal dilatation were more likely to be found in the aortaventralis (n=5), aortic arch (n=3) and iliac arteries (n=3). Most of the vascular lesions were characterized by wall thickening with a normal lumen (n=15) and slight stenosis (n=22). The affected vascular walls were all thickened between 4 and 18 mm. The walls of 19 patients (90.4%) were well circumscribed. The wall thickness of the aorta, including the aortaventralis and aortic arch, was more notable than that of the other vascular sites. Fourteen patients were followed up for 2-24 months. Wall thickness decreased in all cases. The average maximum thicknesses before and after therapy were 12.2±2.7 mm and 6.1±1.8 mm, which were significantly different (P < 0.001). The lumens of two patients were found to be slightly enlarged, while those of the other cases were unchanged after therapy.

CONCLUSION

IgG4-RD vascular lesions can be divided into five types, which are more likely to be present in the aorta and its main branches, and can rapidly diminish after steroid therapy. The lumen may be unchanged or slightly enlarged.

Immunoglobulin G4-related Disease: An Overview

Immunoglobulin G4-related disease (IgG4-RD) is a recently established systemic disease that is characteristically associated with elevated serum immunoglobulin G4 (IgG4) levels and believed to be caused by autoimmune mechanisms. The clinical features of IgG4-RD include (i) systemic distribution, (ii) imaging findings of swelling, nodules, and/or wall thickening, (iii) high serum IgG4 levels, (iv) abundant IgG4-bearing plasma cell infiltration and fibrosis in affected organs, (v) a favorable response to corticosteroid therapy, and (vi) coexistence with other IgG4-RD manifestations simultaneously or in a metachronous fashion. The concept of IgG4-RD was established based on the culmination of specific discoveries. Specifically, a close association between autoimmune pancreatitis (AIP) and high serum IgG4 levels, massive IgG4-bearing plasma cell infiltration in pancreatic tissues affected by AIP, and systemic other organ involvements in AIP with similar IgG4-bearing plasma cell features opened the gateway from AIP to IgG4-RD. The systemic distribution of IgG4-RD seems to be capable of affecting every organ, causing well-established members including AIP, lacrimal and salivary gland lesions such as Mikulicz’s disease, respiratory diseases, sclerosing cholangitis, kidney diseases, and retroperitoneal fibrosis. IgG4-RD has been diagnosed worldwide, and international collaboration efforts on the disease have led to consensus publications on its nomenclature, pathology findings, and management approach. The algorithms developed for the comprehensive diagnostic criteria for IgG4-RD have remarkably increased detection sensitivity. Oral glucocorticoids are the first-line agents for remission induction, and certain patients with high disease activity may benefit from maintenance therapy afterwards. Originally, IgG4-RD had been considered reversible and to have a good prognosis; however, long-term afflictions sometimes result in transition to advanced-stage conditions with dysfunction and/or complicating malignancy. The immunological abnormalities in IgG4-RD have been reported in both innate and adaptive immune systems; however, it remains unclear whether IgG4 has a pathogenic role or a protective one in disease onset and progression.

IgG4-related respiratory disease

IgG4-related diseases (IgG4-RDs), such as autoimmune pancreatitis and IgG4-related Mikulicz disease, are often accompanied by intrathoracic lesions, which are called IgG4-related respiratory disease (IgG4-RRD). IgG4-RRD has few subjective symptoms, and is usually detected during workup of patients with extra-thoracic lesions of IgG4-RD. IgG4-RRD is characterized by various conditions, including masses, nodules, thickening, and infiltration at numerous sites in the thorax through lymphatic routes. Although elevated serum IgG4 concentrations and pathologic evidence of lymphoplasmacytic infiltrates with abundant IgG4-positive plasma cells are characteristic findings of IgG4-RD, other intrathoracic diseases, such as multicentric Castleman disease and malignancy, may present with similar findings. Developing diagnostic criteria for IgG4-RRD, including clinicoradiological and pathological characteristics, is necessary for its appropriate diagnosis.

Comparison of clinical characteristics of radiological forms of autoimmune pancreatitis

BACKGROUND

There is limited understanding of the clinical characteristics of different radiological forms of autoimmune pancreatitis (AIP). This retrospective study compared the clinical features of radiological forms of AIP.

METHODS

A retrospective review was conducted of patients with AIP treated from 2005 to 2015. Based on radiological features, these AIP cases were classified as diffuse (D) or focal (F), and the latter further stratified as head (H), or body and/or tail (B/T). The clinical characteristics and laboratory indices were compared.

RESULTS

Among the 119 patients, 66 (55.5%), 40 (33.6%), and 13 (10.9%) were respectively classified as D-, H-, and B/T-type. Compared with the others, the B/T-type patients were younger at onset, the percentage of men was lower, loss of appetite and weight were less common, and these patients had fewer extrapancreatic lesions (P < 0.05, each). Compared with the other groups, the B/T-type patients showed significantly lower levels of liver enzymes, direct bilirubin, and total bilirubin. No B/T-type patient displayed jaundice or pruritus. Three B/T-type patients progressed to D-type during the natural course of illness.

CONCLUSIONS

D-type and H-type AIP patients had similar clinical features. The B/T-type group differed significantly from the other two types. B/T-type can progress to D-type.

Management of Autoimmune Pancreatitis

Type 1 autoimmune pancreatitis (AIP) is an IgG-4-related systemic disease that can manifest as a pancreatic disorder or another disorder of presumed autoimmune origin. Type 2 disease is typically characterized by absent IgG-4-positive cells. As patients often present with acute pancreatitis, obstructive jaundice, or pancreatic mass, it is imperative to exclude malignancy, a more common diagnosis. AIP may respond to corticosteroids, and has a strong association with other immune-mediated diseases. Recent literature suggests the benefit of immune-modulating therapy, including rituximab, although no consensus exists. This review covers the essentials of diagnosis, but focuses primarily on management of AIP.

MR Imaging of Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is characterized by autoimmune inflammatory destruction of the pancreatic tissue. Imaging plays an essential role in the diagnosis. AIP type 1 is the pancreatic manifestation of immunoglobulin G4 (IgG4)-related disease and is associated with IgG4-positive plasma cell infiltration and fibrosis of multiple organ systems. Type 2 is a related disease with pancreatic inflammation with or without concurrent inflammatory bowel disease. The authors demonstrate the imaging findings that are associated with the pancreatic and extra-pancreatic manifestations of AIP. They emphasize the common MR imaging and magnetic resonance cholangiopancreatography findings to help make the diagnosis of AIP.

IgG4-related Disease - A Systemic Disease that Deserves Attention Regardless of One's Subspecialty

IgG4-related disease (IgG4-RD) is an inflammatory condition characterized by a high serum IgG4 concentration and the abundant infiltration of lymphocytes and IgG4-positive plasma cells in the tissue, as well as spatial (diverse clinical manifestations) and temporal (the possibility of recurrence) multiplicities. Since the initial documentation of IgG4-related disease in patients with autoimmune pancreatitis in 2001, a growing body of evidence has been accumulating to suggest that various-virtually all-organs can be affected by IgG4-RD. In general, steroid therapy is effective and is considered to be the first-line treatment for IgG4-RD. The precise mechanism underlying this systemic disorder has remained unknown. Considering that IgG4-RD was specified as being an intractable disease in 2015, further studies are needed to clarify whether IgG4-RD is indeed a distinct disease entity or a complex of disorders of different etiologies and clinical conditions.

IgG4-related lung disease on the horizon

Immunoglobulin G4 (IgG4) related lung disease is an emerging entity. We report a case of a 42-year-old man presented with fever and cough with minimal sputum. Chest X-ray revealed diffuse reticulonodular shadows. Extensive investigations were performed, including video-assisted thoracoscopic lung biopsy, which confirmed the diagnosis of IgG4-related disease (IgG4-RD) with lung involvement. This case report aims to illustrate that IgG4-related lung involvement can present as diffuse lung nodules and can affect different pulmonary structures. IgG4-RD should always be considered when a similar scenario is encountered.

Current approach to the diagnosis of IgG4-related disease - Combination of comprehensive diagnostic and organ-specific criteria

IgG4-related disease (IgG4-RD) is a fascinating clinical entity proposed by Japanese investigators, and includes a wide variety of diseases, formerly diagnosed as Mikulicz's disease (MD), autoimmune pancreatitis (AIP), interstitial nephritis, prostatitis, retroperitoneal fibrosis, etc. Although all clinicians in every field of medicine may encounter this new disease, a unifying diagnostic criterion has not been established. In 2011, the Japanese IgG4 team, organized by the Ministry of Health, Labor and Welfare (MHLW) of Japan, published comprehensive diagnostic criteria for IgG4-RD. Several problems with these criteria have arisen in clinical practice, however, including the difficulty obtaining biopsy samples from some patients, and the sensitivity and the specificity of techniques used to measure serum IgG4 concentrations. Although serum IgG4 concentration is an important clinical marker for IgG4-RD, its diagnostic utility in differentiating IgG4-RD from other diseases, called IgG4-RD mimickers, remains unclear. This review describes the current optimal approach for the diagnosis of IgG4-RD, based on both comprehensive and organ-specific diagnostic criteria, in patients with diseases such as IgG4-related pancreatitis (AIP), sclerosing cholangitis, and renal, lung and orbital diseases.

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.

Clinical characterization of 52 patients with immunoglobulin G4-related disease in a single tertiary center in Japan: Special reference to lung disease in thoracic high-resolution computed tomography

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a rare multi-organ disorder. Physicians rarely encounter patients with IgG4-RD and its range of symptoms.

METHODS

To elucidate the clinical characterization of IgG4-RD, along with the clinical significance of lung involvement, we retrospectively reviewed the medical records of patients who satisfied the comprehensive diagnostic criteria for IgG4-RD.

RESULTS

We identified 52 patients with IgG4-RD. Of these, 32 patients underwent tissue biopsies, resulting in categorization as definite (n = 23) or possible (n = 9) IgG4-RD cases. Among the 23 definite IgG4-RD cases, those with positive lung involvement (n = 8) had significantly higher values of serum LDH (median 220 IU/L, interquartile range (IQR) 175-378 vs. median 184, IQR 136-249, p = 0.039), IgG (median 2769 mg/dL, IQR 2028-7807 vs. median 2048, IQR 1168-4376, p = 0.009), and soluble interleukin-2 receptors (median 1620 U/mL, IQR 871-2250 vs. median 733, IQR 271-1600, p = 0.003) than those with negative lung involvement (n = 15). Similarly, a significant number of patients with positive lung involvement were positive for rheumatoid factor (71.4% vs. 23.1%, p = 0.041) or hypocomplementemia (50% vs. 0%, p = 0.036). Sixteen patients also showed lung involvement (definite n = 8, possible n = 8); thoracic computed tomography (CT) of these patients revealed mediastinal lymphadenopathies (n = 14, 87.5%), ground glass opacity (n = 11, 68.8%), consolidation (n = 8, 50%), thickening of the bronchovascular bundles (n = 7, 43.8%), small nodules (n = 5, 31.3%), bronchiectasis (n = 4, 25%), and reticular shadows (n = 4, 25%), and pulmonary function tests, using a standard technique involving a single breath, revealed decreased diffusion capacity for carbon monoxide.

CONCLUSIONS

IgG4-RD is associated with diverse thoracic CT findings and a decreased diffusion capacity, and careful multidisciplinary assessment is needed to enable differentiation of IgG4-RD from lymphoproliferative disorders.

Successful treatment of highly advanced immunoglobulin G4-related kidney disease presenting renal mass-like regions with end-stage kidney failure: a case study

Background

Immunoglobulin G4-related kidney disease characterized by immunoglobulin G4-positive plasma cell-rich tubulointerstitial nephritis has distinctive serological and radiological findings. Renal prognosis is good because of a good response to glucocorticoids. Here we report a case of successful treatment of highly advanced immunoglobulin G4-related kidney disease presenting renal mass-like regions with end-stage kidney failure.

Case Presentation

A 59-year-old Japanese man was referred to our hospital because of uremia with a creatinine level of 12.36 mg/dL. Urinalysis revealed mild proteinuria and hyperβ2microglobulinuria, and blood tests showed hyperglobulinemia with an IgG level of 3243 mg/dL and an IgG4 level of 621 mg/dL. Non-contrast computed tomography revealed renal mass-like regions. Based on the findings, immunoglobulin G4-related kidney disease was suspected, however, further radiological examination showed unexpected results. Ga-67 scintigraphy showed no kidney uptake. T2-weighted magnetic resonance imaging revealed high-intensity signals which corresponded to mass-like regions and multiple patchy low-intensity signals in kidney cortex. Finally, the patient was diagnosed with immunoglobulin G4-related kidney disease by renal pathology of severe immunoglobulin G4-positive plasma cell-rich tubulointerstitial nephritis and characteristic fibrosis. He received 50 mg oral prednisolone, which was tapered with a subsequent decrease of serum creatinine and IgG4 levels. One year after initiation of treatment, he achieved normalization of serum IgG4 level and proteinuria, and remained off dialysis with a creatinine level of 3.50 mg/dL. After treatment with steroids, repeat imaging suggested bilateral severe focal atrophy. However, mass-like regions did not show atrophic change although renal atrophy was evident in patchy low-intensity lesions on T2-weighted magnetic resonance imaging. These findings suggest that multiple patchy low-intensity signals and high-intensity mass-like regions were mildly atrophic lesions of immunoglobulin G4-related kidney disease due to severe fibrosis and normal parts of kidney, respectively.

Conclusions

In immunoglobulin G4-related kidney disease with severe kidney failure, radiological findings should be carefully examined. In addition, renal prognosis may be good despite highly advanced tubulointerstitial nephritis and fibrosis.

Association of immunoglobulin G4 and free light chain with idiopathic pleural effusion

The cause of pleural effusion remains uncertain in approximately 15% of patients despite exhaustive evaluation. As recently described immunoglobulin (Ig)G4-related disease is a fibroinflammatory disorder that can affect various organs, including the lungs, we investigate whether idiopathic pleural effusion includes IgG4-associated etiology. Between 2000 and 2012, we collected 830 pleural fluid samples and reviewed 35 patients with pleural effusions undiagnosed after pleural biopsy at Yamaguchi-Ube Medical Center. Importantly, IgG4 immunostaining revealed infiltration of IgG4-positive plasma cells in the pleura of 12 patients (34%, IgG4⁺ group). The median effusion IgG4 level was 41 mg/dl in the IgG4⁺ group and 27 mg/dl in the IgG4^- group (P < 0·01). The light and heavy chains of effusion IgG4 antibodies of patients in the IgG4⁺ group were heterogeneous by two-dimensional electrophoresis, indicating the absence of clonality of the IgG4 antibodies. Interestingly, the κ light chains were more heterogeneous than the λ light chains. The measurement of the κ and λ free light chain (FLC) levels in the pleural fluids showed significantly different κ FLC levels (median: 28·0 versus 9·1 mg/dl, P < 0·01) and κ/λ ratios (median: 2·0 versus 1·2, P < 0·001) between the IgG4⁺ and IgG4^- groups. Furthermore, the κ/λ ratios were correlated with the IgG4⁺ /IgG⁺ plasma cell ratios in the pleura of the IgG4⁺ group. Taken together, these results demonstrate the involvement of IgG4 in certain idiopathic pleural effusions and provide insights into the diagnosis, pathogenesis and therapeutic opportunities of IgG4-associated pleural effusion.

Ophthalmic manifestations in IgG4-related disease: Clinical presentation and response to treatment in a French case-series

IgG4-related disease (IgG4-RD) is characterized by variable tissue or organ involvements sharing common pathological findings. Orbital or orbital adnexa involvement of the disease has been reported in a few case series. The aim of our study was to characterize and analyze ophthalmic manifestations from a nationwide French case-series.Patients with IgG4-RD and orbital or orbital adnexa involvement included in the French multicentric IgG4-RD case-registry were identified. Only patients fulfilling "modified" comprehensive diagnostic criteria with pathological documentation were retained for the study. Clinical, biological, pathological, radiological findings and data regarding the response to treatment were retrospectively analyzed.According to our data registry, the frequency of IgG4-related ophthalmic disease (IgG4-ROD) was 17%. Mean age at diagnosis was 55.1 ± 7.1 years with a male/female ratio of 2.2. The 19 cases of IgG4-ROD consisted of lacrimal gland (68.4%), soft tissue (57.9%), extra-ocular muscles (36.8%), palpebral (21.1%), optical nerve (10.5%), orbital bone (10.5%), and mononeuritis (V1 and/or V2, 10.5%) involvements. IgG4-ROD was bilateral in 57.9% of cases. Extra-ophthalmic manifestations were reported in 78.9% of cases. All patients responded to prednisone but two-thirds of patients relapsed within a mean (SD) of 9.8 (3.5) months and 72.2% required long-term glucocorticoids and/or immunosuppressive agents. Eight patients were treated by rituximab with a favorable response in 87.5% of cases.Lacrimal involvement is the most frequent ophthalmic manifestation of IgG4-RD and is frequently associated with extra-orbital manifestations. Despite initial favorable response to steroids, the long-term management of relapsing patients needs to be improved.

Characteristics of immunoglobulin G4-related aortitis/periaortitis and periarteritis on fluorodeoxyglucose positron emission tomography/computed tomography co-registered with contrast-enhanced computed tomography

BACKGROUND

We aimed to assess the positivity, distribution, quantitative degree of vessel inflammation, and clinical characteristics of IgG4-related aortitis/periarteritis and periarteritis (IgG4-aortitis), and to examine the difference in these characteristics between cases with and without IgG4-aortitis, using fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) co-registered with contrast-enhanced CT (CECT). We retrospectively evaluated 37 patients with IgG4-related disease (IgG4-RD) who underwent both FDG-PET/CT and CECT. The arterial SUVmax and its value normalized to the background venous blood pool (BP)-the target-to-background ratio (TBR) in the entire aorta and the major first branches-were measured. Active vascular inflammation was considered in cases with a higher FDG uptake than BP and a thickened arterial wall (>2 mm).

RESULTS

Fifteen (41%) patients exhibited IgG4-aortitis. Most patients (80%) showed multiple region involvement. The entire aorta, including the major first branches, were involved, typically showing a thickened wall and high FDG uptakes. The most common site was the iliac arteries (35%), followed by the infrarenal abdominal aorta (33%), thoracic aorta (8%), first branches of the thoracic aorta (8%), suprarenal abdominal aorta (6%), and the first branches of the abdominal aorta (5%). The IgG4-aortitis-positive vessel regions were thickened, with an average maximal wall thickness of 6.3 ± 2.9 mm. The SUVmax and TBR values were significantly higher in the IgG4-aortitis-positive regions (median 3.7 [1.6-5.5] and 2.1 [1.4-3.7], respectively) than in the IgG4-aortitis-negative regions (median 2.1 [1.2-3.7] and 1.3 [0.9-2.3], respectively; p < 0.0001). The IgG4-aortitis-positive group patients were older (69.5 ± 6.0 vs. 63.3 ± 12.6 years, respectively) and had a higher male predominance (80 vs. 55%, respectively) than the negative group, although the differences were not significant (p = 0.17 and p = 0.06, respectively).

CONCLUSIONS

We investigated the image characteristics of IgG4-aortitis. The entire aorta and major branches can be involved with more than 2-fold higher FDG uptake than the venous background pool, and with wall thickening. The most common involved site is the iliac arteries, followed by the infrarenal abdominal aorta.

A case of proteinase 3 anti-neutrophil cytoplasmic antibody (PR3-ANCA) positive/IgG4-related lung disease

IgG4-related lung disease (IgG4-RLD) is a rare and chronic progressive autoimmune disease. We report a case of IgG4-related inflammatory pseudo-tumor of the lung that was seropositive for proteinase 3 anti-neutrophil cytoplasmic antibody (PR3-ANCA). A 61-year-old male had a mass lesion in the right lower lung field in chest X-ray. Transbronchial lung biopsy resulted in a pathological diagnosis of IgG4-RLD. The condition was improved by hormonal therapy.