IgG4-related sclerosing disease incorporating sclerosing pancreatitis, cholangitis, sialadenitis and retroperitoneal fibrosis with lymphadenopathy

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

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

Assessment of specificity of dermatopathologic criteria for IgG4-related skin disease

BACKGROUND

IgG4-related disease (IgG4-RD) represents a recently characterized multisystemic fibroinflammatory condition that can manifest a spectrum of skin findings (IgG4-related skin disease; IgG4-RSD). Histopathologic and immunohistochemical criteria have been proposed; however, the specificity of these criteria merits scrutiny given the potential histopathologic overlap of IgG4-RSD and both neoplastic and inflammatory skin conditions featuring lymphoplasmacytic infiltrates (IgG4-RSD mimics). This study sought to assess the specificity of the criteria by quantifying the frequency by which an expanded spectrum of IgG4-RSD mimics meet proposed thresholds.

METHODS

Following IRB approval, a total of 69 cases of IgG4-RD mimics, representing 14 different diagnoses featuring plasma cells, were reviewed and analyzed for the following histopathologic and immunohistochemical features: (i) maximum IgG4+ count/high-powered field (hpf) >200; (ii) IgG4/IgG ratio >0.4 averaged over 3 hpfs; (iii) IgG4+ count >10 per hpf.

RESULTS

Screening for IgG4-RSD by histopathologic criteria demonstrated the high frequency of lymphoplasmacytic infiltrates, contrasted with the rarity of storiform fibrosis (only one case of erythema elevatum diutinum [EED]) and obliterative phlebitis (0 cases). By immunohistochemical criteria, the analysis revealed that no cases exceeded 200 IgG4+ cells; 13% (9/69) cases demonstrated an IgG4/IgG ratio of >0.4 averaged over 3 hpfs; and 23% (16/69) cases demonstrated a mean IgG4+ count of >10 per hpf.

CONCLUSION

Application of proposed IgG4-RSD histopathologic criteria to an expanded spectrum of potential IgG4-RSD mimics (to include cutaneous marginal zone lymphoma, syphilis, necrobiosis lipoidica, lichen sclerosus, ALHE, psoriasis, lymphoplasmacytic plaque, EED, and erosive pustular dermatosis), highlights the relative nonspecificity of lymphoplasmacytic infiltrates contrasted with the stringency of storiform fibrosis and obliterative fibrosis. Furthermore, an IgG4+ cell count of >10 per hpf and an IgG4/IgG ratio of >0.4 are not specific to IgG4-RSD alone. In the appropriate clinical context for IgG4-RSD, histopathologic features still represent the entry threshold for diagnosis consideration, which then allows for further screening by immunohistochemical criteria.

Recent Progress on the Roles of Regulatory T Cells in IgG4-Related Disease

IgG4-related disease (RD) is a proposed concept of systemic inflammatory condition from Japanese researchers. Patients with IgG4-RD manifest several immunological and histological characterizations in the organs involved, including elevated levels of serum IgG4 and lympho-plasmacytic infiltration, storiform fibrosis, IgG4-positive plasma cells infiltration, and obstructive phlebitis. Nevertheless, the pathogenesis of IgG4-RD still remains unclear. It has been made clear that several immune cells with regulatory function play a vital part in several diseases. In particular, abnormalities in the function and proportion of regulatory T cells (Tregs) are implicated in several diseases, and their part in IgG4-RD has been investigated. This review offers an overview of the research in IgG4-RD related to Tregs. Herein, the basic information of Tregs, knowledge gained from animal models involving Tregs, and the role of IgG4-RD has been provided. We also included the immunological mechanisms of IgG4-RD based on the data accumulated so far in our hypothesis.

IgG4-Related Sclerosing Cholangitis: Rarely Diagnosed, but not a Rare Disease

IgG4-related sclerosing cholangitis, a biliary manifestation of an IgG4-related disease, belongs to the spectrum of sclerosing cholangiopathies which result in biliary stenosis. It presents with signs of cholestasis and during differential diagnosis it should be distinguished from cholangiocarcinoma or from other forms of sclerosing cholangitis (primary and secondary sclerosing cholangitis). Despite increasing information and recently established diagnostic criteria, IgG4-related sclerosing cholangitis remains underdiagnosed in routine clinical practice. The diagnosis is based on a combination of the clinical picture, laboratory parameters, histological findings, and a cholangiogram. Increased serum IgG4 levels are nonspecific but are indeed a part of the diagnostic criteria proposed by the Japan Biliary Association and the HISORt criteria for IgG4-SC. High serum IgG4 retains clinical utility depending on the magnitude of elevation. Approximately 90% of patients have concomitant autoimmune pancreatitis, while 10% present with isolated biliary involvement only. About 26% of patients have other organ involvement, such as IgG4-related dacryoadenitis/sialadenitis, IgG4-related retroperitoneal fibrosis, or IgG4-related renal lesions. A full-blown histological finding characterized by IgG4-enriched lymphoplasmacytic infiltrates, obliterative phlebitis, and storiform fibrosis is difficult to capture in practice because of its subepithelial localization. However, the histological yield is increased by immunohistochemistry, with evidence of IgG4-positive plasma cells. Based on a cholangiogram, IgG-4 related sclerosing cholangitis is classified into four subtypes according to the localization of stenoses. The first-line treatment is corticosteroids. The aim of the initial treatment is to induce clinical and laboratory remission and cholangiogram normalization. Even though 30% of patients have a recurrent course, in the literature data, there is no consensus on chronic immunosuppressive maintenance therapy. The disease has a good prognosis when diagnosed early.

Hyper IgG4-Related Disease Presenting with Orbital Tumor and Immune Deficiency

We report a case of IgG4-RD in a patient with high IgG4 levels, low functional antibodies, and low IgM levels. He presented with bilateral orbital pseudotumors and, after initial improvement on corticosteroids, relapsed with recurrent pleural effusion and pelvic pseudotumor. He had a grossly elevated serum IgG (1905 mg/dl) with elevations in all IgG subclasses but marked elevation in IgG4 (412 mg/dl), low IgM, and low pneumococcal antibodies. Orbital mass biopsy showed polyclonal lymphocytic infiltration and increased IgG4 plasma cells. The patient was started on prednisone and tried several immunosuppressive medications including mycophenolate mofetil, methotrexate, hydroxychloroquine, and azathioprine with decrease in size of the orbital pseudotumor. During a period when the patient stopped his medications, the pseudotumor enlarged with new development of recurrent pleural effusions. He was also found to have a pelvic mass that was biopsy positive for IgG4 proliferation. This case with progression to multiorgan involvement highlights the importance of identifying patients with IgG4-related disease. In contrast to previous cases with normal-to-high IgM, the IgM was low with impaired functional antibodies.

Sclerosing Sialadenitis Is Associated With Salivary Gland Hypofunction and a Unique Gene Expression Profile in Sjögren's Syndrome

Purpose

To develop a novel method to quantify the amount of fibrosis in the salivary gland and to investigate the relationship between fibrosis and specific symptoms associated with Sjögren’s syndrome (SS) using this method.

Materials and Methods

Paraffin-embedded labial salivary gland (LSG) slides from 20 female SS patients and their clinical and LSG pathology data were obtained from the Sjögren’s International Collaborative Clinical Alliance. Relative interstitial fibrosis area (RIFA) in Masson’s trichrome-stained LSG sections was quantified from digitally scanned slides and used for correlation analysis. Gene expression levels were assessed by microarray analysis. Core promoter accessibility for RIFA-correlated genes was determined using DNase I hypersensitive sites sequencing analysis.

Results

RIFA was significantly correlated with unstimulated whole saliva flow rate in SS patients. Sixteen genes were significantly and positively correlated with RIFA. In a separate analysis, a group of differentially expressed genes was identified by comparing severe and moderate fibrosis groups. This combined set of genes was distinct from differentially expressed genes identified in lung epithelium from idiopathic pulmonary fibrosis patients compared with controls. Single-cell RNA sequencing analysis of salivary glands suggested most of the RIFA-correlated genes are expressed by fibroblasts in the gland and are in a permissive chromatin state.

Conclusion

RIFA quantification is a novel method for assessing interstitial fibrosis and the impact of fibrosis on SS symptoms. Loss of gland function may be associated with salivary gland fibrosis, which is likely to be driven by a unique set of genes that are mainly expressed by fibroblasts.

ALK-negative lung inflammatory myofibroblastic tumor in a young adult: A case report and literature review of molecular alterations

RATIONALE

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal tumor that is prevalent among children and adolescents. Surgery is the most important therapeutic approach for IMT and complete resection is recommended. Although 50% of IMTs show anaplastic lymphoma kinase (ALK) rearrangements, crizotinib has proven an effective therapeutic approach. However, the genetic landscape of this tumor is still not fully understood and treatment options are limited, especially in the majority of ALK-negative tumors.

PATIENT CONCERNS

We describe the clinical case of a healthy 18-year-old female in whom a pulmonary nodule was incidentally detected.

DIAGNOSES

Following a small increase in the size of the nodule, the patient underwent both 18FDG-PET/CT and 68Ga-PET/CT, resulting in a suspicion of bronchial hamartoma.

INTERVENTIONS

The patient underwent surgery and a salivary gland-like lung tumor was diagnosed.

OUTCOMES

After surgery, the patient was referred to our cancer center, where a review of the histology slides gave a final diagnosis of ALK-negative lung IMT. Given the histology, it was decided not to administer adjuvant therapy and the patient was placed in a 3-monthly follow-up program. The patient is still disease-free 2 years post-surgery.

LESSONS

Although there is no standard of care for the treatment of IMT, identifying genomic alterations could help to redefine the management of patients with negative-ALK disease. Our review of the literature on IMT and other kinase fusions revealed, in addition to ALK rearrangements, the potential association of ROS1, NTRK, RET, or PDGFR beta alterations with the tumor.

Not All Küttner Tumors Are IgG4-Related Disease (IgG4-RD)

Küttner tumor is an uncommon cause of salivary gland enlargement that most frequently affects the submandibular gland. More recently it has been considered a manifestation of IgG4-related disease (IgG4-RD) and synonymous with chronic sclerosing sialadenitis (CSS). We present a series of cases to emphasize this clinical entity as a disease pattern and presentation that is separate from IgG4-RD. Retrospective case series of 3 patients with unilateral salivary gland enlargement, or "Küttner tumor," histologically classified as "chronic sclerosing sialadenitis," The clinical history, radiology reports, laboratory studies, and pathology slides were reviewed for each case. Radiology showed discrete unilateral mass-like lesions in all three cases. Immunohistochemistry showed reduced tissue IgG4-positive plasma cells in two cases and increased numbers in one case, but insufficient to diagnose IgG4-RD. Storiform fibrosis was not seen in all cases and did not coincide with increased IgG4-positive plasma cells. A systemic workup, including serum IgG4 levels in two cases, was normal. A brief review of the literature on the spectrum of salivary gland involvement by IgG4-RD is presented. Küttner tumor is not necessarily the same as chronic sclerosing sialadenitis and is not always associated with IgG4-related disease. This report includes the second documented case of Küttner tumor of the sublingual gland.

IgG4-related lymphadenopathy – a difficult diagnosis

Background

The IgG4-related disease (IgG4-RD) is a systemic immune-mediated non-neoplastic disease associated with IgG4 positive plasma cells and fibrosis that often presents as a mass lesion. Although the disease could affect virtually any anatomical site, there are strong predilections for certain organs. IgG4-related lymphadenopathy can exhibit a broad morphologic spectrum. We describe a patient with IgG4-related lymphadenopathy with overlapping histological features that proved to be a diagnostic red herring.

Case presentation

A 58-year-old gentleman with multiple co-morbidities presented with obstructive jaundice, elevated transaminases, and bilateral inguinal and left axillary lymphadenopathy. Imaging of the abdomen and pelvis showed circumferential soft tissue thickening resulting in luminal narrowing of common and proximal bile duct with upstream intrahepatic biliary radicle dilatation, multiple enlarged lymph nodes, and homogenous soft tissue lesions in the tail of the pancreas and bilateral renal cortical parenchyma with perinephric soft tissue extension. Left inguinal, and axillary lymph node excision biopsies were suggestive of IgG4-RD. Serum IgG4 levels performed subsequently, were markedly elevated. The patient was treated with prednisone which led to resolutions of his symptoms, reduction in the size of the lesions, and reversal of abnormal laboratory parameters.

Conclusion

The diagnosis of IgG4-RD in lymph node excision biopsy is a difficult call to make and needs a multidisciplinary team. An early diagnosis renders timely intervention and prevents the progression of the disease and its complications.

Clinicopathological differential diagnosis of IgG4-related disease: A historical overview and a proposal of the criteria for excluding mimickers of IgG4-related disease

IgG4-related disease (RD) is a relatively new entity, which was first proposed in 2001. Since then, clinical and pathological characteristics of the disease have been investigated. As IgG4-RD has been studied extensively, the diagnostic criteria for IgG4-RD of each organ and the comprehensive diagnostic criteria for IgG4-RD have also been developed. However, one of the biggest challenges in the field is distinguishing between IgG4-RD and mimickers, which show overlapping features with IgG4-RD. It is now known that some non-IgG4-RDs may meet the diagnostic criteria of IgG4-RD and can be misdiagnosed as IgG4-RD. However, accurate diagnosis is crucial, as the treatments for IgG4-RD and those for other diseases that may be misdiagnosed as IgG4-RD are different. This prompted us to create and propose comprehensive exclusion criteria for IgG4-RD. In this review, we have described the comprehensive exclusion criteria for IgG4-RD, with a historical overview of the disease. These exclusion criteria were recently created by the Research Program for Intractable Disease of the Ministry of Health, Labor, and Welfare of Japan, All Japan IgG4 team, to support correct and accurate diagnosis of IgG4-RD.

Primary cutaneous Rosai-Dorfman disease; a case-based review of a diagnostically and therapeutically challenging rare variant

Primary cutaneous Rosai-Dorfman disease is a rare form of Rosai-Dorfman disease limited to the skin. The diagnosis of primary cutaneous disease is based on a combination of clinical presentation, histopathology, and the detection of S100+, CD68+, and CD1a- histiocytic immunophenotyping. However, the diagnosis of primary cutaneous disease is often difficult and significantly delayed due to the non-specific nature of its histologic and clinical features. In this review, we describe four cases in order to familiarize pathologists and dermatopathologists with the clinicopathologic correlation of primary cutaneous Rosai-Dorfman disease and to help facilitate early diagnosis. In addition, we discuss the proposed pathophysiology and molecular etiology of this tumor, and its relationship with IgG4 sclerosing disease.

Successful treatment based on molecular biological assessment of invasive anaplastic lymphoma kinase-positive inflammatory myofibroblastic tumor of the lung

BACKGROUND

Inflammatory myofibroblastic tumor (IMT) of the lung is rare. This disease often shows neoplastic features with anaplastic lymphoma kinase positiveness as well as inflammatory features, such as steroid-responsive immunoglobulin G4 (IgG4)-related sclerosing disease. Since many cases have been reported as advanced, various treatment strategies should be considered based on clinical and biological features of each case.

CASE PRESENTATION

We report a 49-year-old male with IMT, which seemed invading the left atrium from preoperative imaging modalities. Serological and pathological examinations from the biopsy specimen revealed high expression of anaplastic lymphoma kinase expression in the tumor. On the other hand, IgG4/IgG ration in the tumor was small, where a therapeutic effect of steroid was not expected, leading to surgical treatment rather than a steroid administration. The tumor was completely resected en bloc with the right lower lobe of the lung and a part of the left atrium. The postoperative course of the patient was uneventful. The patient has remained recurrence free over 5 years from the surgery.

CONCLUSION

In this case, preoperative biological assessment prior to the treatment led to a good clinical course. We believe that molecular biological examination is important in the determination of treatment strategy for this rare disease as well as imaging modalities.

Impaired expression of innate immunity-related genes in IgG4-related disease: A possible mechanism in the pathogenesis of IgG4-RD

Background: IgG4-related disease (IgG4-RD) is characterized by elevated serum IgG4 and tissue infiltration by IgG4-positive plasma cells. The pathogenesis of this disease is not clear. Transcriptome analysis was performed to identify genes over- and under-expressed in patients with IgG4-RD.Method: DNA microarray analysis was performed using RNA from peripheral blood mononuclear cells of two patients with IgG4-RD and four healthy individuals. Genes showing a greater than threefold change in expression in IgG4-RD patients following steroid therapy were identified. Four genes related to innate immunity such as transcobalamin I (TCN1), secretory leukocyte peptidase inhibitor (SLPI), bactericidal/permeability-increasing protein (BPI) and lactotransferrin (LTF) were assessed by real-time PCR in 15 IgG4-RD patients and 13 healthy individuals.Result: DNA microarray analysis identified 30 genes showing a greater than threefold change in expression in IgG4-RD patients following steroid therapy. Real-time RT-PCR showed that the levels of mRNAs encoding TCNI and SLPI, except for BPI and LTF, were significantly lower in patients with IgG4-RD than in healthy people. The levels of all four mRNAs in patients with IgG4-RD were significantly increased after steroid treatment.Conclusion: These results indicate that reduction in expression of innate immunity-related genes may participate in the pathogenesis of IgG4-RD that steroid treatment may rectify impaired innate immunity as well as acquired immunity.

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

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

Gastrointestinal manifestation of immunoglobulin G4-related disease: clarification through a multicenter survey

BACKGROUND

Several reports on immunoglobulin (Ig)G4-related disease (IgG4-RD) with gastrointestinal involvement (IgG4-related gastrointestinal disease; IgG4-GID) have been published, although this entity has not been fully established clinicopathologically. Thus, we carried out a multicenter survey.

METHODS

Patients with possible IgG4-GID who underwent resection were collected. Histologic slides were reevaluated, and eight cases with diffuse lymphoplasmacytic infiltration but without numerous neutrophils, granulations or epithelioid granulomas were further analyzed.

RESULTS

Overall, the IgG4 counts (87-345/high-power field) and IgG4/IgG-positive ratio were high (44-115%). The demographic findings included advanced age among the patients (55-80 years) and male preponderance (six cases). Six lesions (five gastric, one esophageal), consisting of lymphoplasmacytic infiltration with neural involvement in the muscularis propria and/or bottom-heavy plasmacytosis in the gastric mucosa, were histologically regarded as highly suggestive of IgG4-RD. Storiform fibrosis and obliterative phlebitis were found in two cases, and the former gave rise to a 7-cm-sized inflammatory pseudotumor (IPT) in one case. Ulceration and carcinoma co-existed in three and two lesions, respectively. All the patients had other organ involvement (OOI), and serum IgG4 levels were markedly elevated (four of five patients). The remaining two cases with gastric IPTs featuring reactive nodular fibrous pseudotumor or nodular lymphoid hyperplasia were regarded as possible cases of IgG4-RD because of the histologic findings and lack of OOI.

CONCLUSIONS

IgG4-GID is found in the setting of IgG4-RD, often with ulceration or cancer. Characteristic histologic findings are observed in the muscularis propria and gastric mucosa. Cases with IPT may be heterogeneous, and there may be mimickers of IgG4-GID.

Sialendoscopic management of autoimmune sialadenitis: a review of literature

Autoimmune diseases of major salivary glands include Sjögren's syndrome and a complex of disorders classified as immunoglobulin G4-related diseases. These pathologies are characterised by an autoimmune reaction mediated by T-helper lymphocytes that targets the ducts of exocrine glands in Sjögren's syndrome and glandular parenchyma in immunoglobulin G4-related diseases. Immunoglobulin G4-related diseases represent recently introduced multi-organ diseases that also involve the salivary glands. However, the morbid conditions once known as Mikulicz's disease and Kuttner's tumour were recently considered as two variants of immunoglobulin G4-related diseases affecting the major salivary glands ( immunoglobulin G4-related sialadenitis). This review briefly summarises the pathogenesis and clinical features of autoimmune diseases of the major salivary glands, focusing on the diagnostic and therapeutic role of sialendoscopy.

IgG4-Related Disease with lymphadenopathy Presenting as a Cervical lymph node enlargement

During the course of evaluation and management of neck masses, consideration for Immunoglobulin G4-related disease (IgG4-RD) should be given. IgG4-RD is relatively a new growing entity of immune-mediated origin, characterized by a mass-forming lesion, the infiltration of IgG4-positive plasma cells and occasionally elevated serum IgG4. The most common manifestations are parotid and lacrimal swelling, lymphadenopathy and autoimmune pancreatitis.A previously healthy 72-year-old man was referred to our clinic with a 2-month history of left cervical lymph node enlargement without systemic manifestations . A cervical lymph node biopsy was planned because of elevated serum IgG4 levels. Pathological findings showed prominent infiltration of IgG4-postive plasma cells in the lymph node. After steroid therapy, a computed tomography scan revealed a decrease in the cervical lymph node size.This case illustrates the importance of including IgG4-RD in the differential diagnosis of a cervical lymph node enlargement.

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.

Neurological Manifestations of IgG4-Related Disease

OPINION STATEMENT

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

Roles of Regulatory T and B Cells in IgG4-Related Disease

Immunoglobulin G4 (IgG4) -related disease (RD) is a newly recognized systemic disease. Although there are several forms of IgG4-RD reported under various names, depending on the target organ and characteristics, patients with IgG4-RD manifest several immunologic and histologic abnormalities including increased levels of serum IgG4 and storiform fibrosis with infiltration of lymphocytes and IgG4-positive plasmacytes in the involved organs. However, the pathophysiology remains unclear. Regulatory immune cells play an important role in several immune-related diseases. In particular, abnormalities in regulatory T cell (Treg) and regulatory B cell (Breg) numbers and function are implicated in several immune-related (include autoimmune) conditions, and their roles in IgG4-RD have recently begun to be investigated. We provide an overview of the research conducted to date on Tregs and Bregs in IgG4-RD. We highlight the basic functions of these cells, their changes in patients with various forms of IgG4-RD, and insight gained from animal models of the disease. Based on the evidence accumulated thus far, we proposed a hypothesis for the pathophysiological mechanism of IgG4-RD with respect to the roles regulatory immune cells, and highlight the questions and venues of research deserving of further attenuation, Over all, we demonstrate that Tregs and Bregs have a clear impact on IgG4-RD, and further exploration of this field is expected to lead to a better mechanistic understanding of the disease, hopefully resulting in the in the discovery of new therapeutic targets.

Uncommon situation and presentation of chronic sclerosing sialadenitis

Chronic sclerosing sialadenitis of the parotid gland is a very uncommon chronic inflammatory salivary gland disease. Clinically, it presents as a slow-growing painful. Histologically, it showed a chronic inflammation and fibrosis. This case report highlights the clinical, radiological and histological aspects of this disease. We report unusual case of chronic sclerosing sialadenitis of the parotid in a 12-year-old man. CT detected a mass of tissue density in the right parotid. The evolution was marked by spontaneous fistula allowing a surgical biopsy. The mass regressed after corticosteroids. The follow-up was normal. The location, age and presentation make our case very interesting.

IgG4-related mastitis, a rare disease, can radiologically and histologically mimic malignancy

IgG4-related disease (IgG4-RD) is characterised by high serum concentrations of IgG4, dense lymphoplasmacytic infiltrates, storiform fibrosis and increased IgG4-positive plasma cells in tissues. This systemic disease occurs in various organs metachronously, but IgG4-related mastitis appears extremely rare. We report a case of IgG4-related mastitis, radiologically considered to represent breast cancer mainly composed of intraductal component and requiring histological differentiation from mucosa-associated lymphoid tissue (MALT) lymphoma. The breast mass disappeared with steroid therapy. When patients have a breast mass, regardless of the presence or absence of IgG4-RD, IgG4-related mastitis should be considered in addition to breast cancer. If histological findings show dense lymphoplasmacytic infiltrates, IgG4-related mastitis should be suspected in addition to malignant lymphoma, and lack of monoclonality should be confirmed. To avoid unnecessary surgery or chemotherapy, knowledge and accurate diagnosis of the entity of IgG4-related mastitis is necessary.

Comparison of the multidetector-row computed tomography findings of IgG4-related sclerosing cholangitis and extrahepatic cholangiocarcinoma

AIM

To compare the multidetector-row computed tomography (MDCT) findings of IgG4-related sclerosing cholangitis (IgG4-SC) and extrahepatic cholangiocarcinoma (EH-CCA).

MATERIALS AND METHODS

Two radiologists who had no knowledge of the patients' clinical information retrospectively evaluated the CT findings of patients with IgG4-SC (n=33) and EH-CCA (n=39) on a consensus basis. Another radiologist measured the biliary lesions. IgG4-SC was diagnosed using the Japan Biliary Association criteria (2012) or the Mayo Clinic's HISORt criteria. EH-CCA was diagnosed based on surgical findings.

RESULTS

Compared with EH-CCA, IgG4-SC exhibited the following findings significantly more frequently: (a) wall thickening alone, (b) concentric wall thickening, (c) smooth inner margins, (d) homogeneous attenuation in the arterial phase, (e) a lesion involving the intrapancreatic bile duct, (f) smooth outer margins, (g) fully visible lumen, (h) a funnel-shaped proximal bile duct, (i) skip lesions, and (j) abnormal pancreatic findings. Conversely, (k) dual-layered attenuation in all phases was significantly more common in EH-CCA. The specificity values of parameters (e-k) were >80%. Regarding dimensions, (l) the biliary lesions were longer in IgG4-SC than in EH-CCA. (m) The diameters of the dilated proximal common bile duct and (n) the dilated proximal intrahepatic bile duct were smaller in IgG4-SC than in EH-CCA.

CONCLUSION

A number of CT findings are useful for differentiating between IgG4-SC and EH-CCA. CT findings (e-k) are particularly useful for this purpose.

IgG4-related disease: current challenges and future prospects

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

Clinical review of pulmonary manifestations of IgG4-related disease

IgG4-related disease (IgG4-RD) is a recently recognized systemic disease characterized by tumefactive lesions in various organ systems. The list of organs that can be involved continues to expand, and recently computed tomography (CT) descriptions of the pulmonary lesions found in the disease have been described. The clinical symptoms are nonspecific and may include cough, dyspnea, chest pain, and fever. The appropriate clinical presentation along with elevated serum IgG4 concentrations and pathologic evidence of lymphoplasmacytic infiltrates with abundant IgG4-positive plasma cells and storiform fibrosis is consistent with the disease. Steroids are used to treat this disease in addition to immunosupressives such as cyclosporine or rituxumab for steroid refractory disease. The pulmonary manifestations and imaging features can often mimic malignancy, and as such knowledge of the diagnostic, clinicopathologic, and radiographic features of the disease is required in order to provide appropriate diagnostic workup and treatment.

Diagnostic Approach to the Complexity of IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a systemic disease characterized by the infiltration of IgG4-bearing plasma cells and, more importantly, distinctive histopathological features: storiform fibrosis, obliterative phlebitis, a lymphoplasmacytic infiltrate, and mild-to-moderate tissue eosinophilia. The diagnostic approach is complex and relies on the coexistence of various clinical, laboratory, and histopathological findings, none of which is pathognomonic in and of itself. IgG4-related disease should be suspected in patients presenting with unexplained enlargement or swelling of 1 or more organs or tissue organs. Four laboratory abnormalities often provide initial clues to the diagnosis of IgG4-RD: peripheral eosinophilia, hypergammaglobulinemia, elevated serum IgE levels, and hypocomplementemia. Elevated serum IgG4 levels provided critical information in identifying the first cases of IgG4-RD, but recent studies have reported substantial limitations to the measurement of serum IgG4 concentrations, precluding reliance on serum IgG4 concentrations for diagnostic purposes. In contrast, new studies have suggested a promising role of flow cytometry studies in the diagnosis and longitudinal management of IgG4-RD. Demonstration of the classic histopathological features of IgG4-RD remains crucial to diagnosis in most cases, and biopsy proof is preferred strongly by most disease experts before the initiation of treatment. Of note, the multiorgan nature of IgG4-RD was first established in 2003. This review intends to provide most recent knowledge about the clinical, laboratory, radiological, and pathological characteristics of IgG4-RD that may guide the physician to establish an early diagnosis. We searched PubMed and MEDLINE for relevant articles published between January 1, 2000, and November 1, 2014, using the search terms IgG4 and IgG4-related.

Dermatopathic Lymphadenopathy With Increased IgG4-Positive Plasma Cells

Both dermatopathic lymphadenopathy (DL) and immunoglobulin G4-related disease (IgG4-RD) are frequently complicated with allergic diseases. However, the relationship between DL and IgG4-RD is not well known. To clarify this relationship on the basis of clinical and pathological findings, including IgG4-positive (IgG4+) plasma cell infiltration in lymph nodes (LNs) of DL patients, we analyzed LNs of 11 DL patients using immunostaining of IgG, IgG4, forkhead box P3 (FOXP3), transforming growth factor (TGF)-β, interferon (IFN)-γ, and matrix metalloproteinase (MMP)-1, MMP-8, and MMP-13. Toluidine blue staining was also performed to identify mast cells. Of 3 patients with a high ratio of IgG4+/IgG+ cells (>40%) and elevated serum IgG4 levels, 2 developed IgG4-RD, whereas the other patient did not. Of 8 patients with a low ratio of IgG4+/IgG+ cells (<40%) or no infiltration of IgG4+ cells, 5 who could be followed did not develop IgG4-RD. The numbers of mast cells were similar to those of TGF-β-positive cells, and serial sections showed that mast cells possibly produce TGF-β. LNs of DL patients with a high ratio of IgG4+/IgG+ cells had significantly more mast cells and TGF-β-positive cells than those of patients with a low ratio of IgG4+/IgG+ cells or no infiltration of IgG4+ cells. However, no fibrosis was observed in LNs of both groups. IFN-γ was positive in interdigitating dendritic cells, Langerhans cells, and macrophages. MMP-1, MMP-8, or MMP-13 was expressed in macrophages. The lack of fibrosis in LNs may have been due to the production of IFN-γ, MMP-1, MMP-8, or MMP-13. Thus, DL with increased IgG4+ cells seems to be a phenotype of IgG4-RD in LNs.

Lymphoplasmacytic sclerosing pancreatitis without IgG4 tissue infiltration or serum IgG4 elevation: IgG4-related disease without IgG4

Type 1 autoimmune pancreatitis can be diagnosed by and is synonymous with its pathognomonic histopathologic appearance called lymphoplasmacytic sclerosing pancreatitis. Type 1 autoimmune pancreatitis, also called IgG4-related pancreatitis, is the pancreatic manifestation of IgG4-related disease. However, the role of IgG4 in the pathogenesis of IgG4-related disease is unclear. We describe patients with LPSP without serum or tissue IgG4 abnormalities. From the Mayo Clinic database of autoimmune pancreatitis patients, we identified three patients with histologically confirmed type 1 autoimmune pancreatitis (lymphoplasmacytic sclerosing pancreatitis) who had normal serum IgG4 and no increase in IgG4-positive plasma cells in tissue. We reviewed original clinical records and pathologic specimens, and describe the clinical and histologic features of these three patients. All patients (age/gender: 63/F, 70/M and 68/M) had normal serum IgG and IgG4 levels, and multiple sections of pancreatic histology did not show increased IgG4-positive plasma cells. Two patients were diagnosed retrospectively following pancreatic surgery, one relapsed in another organ and one has remained relapse free. Another patient was diagnosed by pancreatic core biopsy and has suffered multiple relapses that have been controlled by rituximab. These cases highlight the fact that although the currently agreed upon name for type 1 autoimmune pancreatitis is IgG4-related pancreatitis, serum and tissue IgG4 abnormalities are best considered characteristic, but not essential for the diagnosis of this enigmatic condition.

Diagnosis of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a distinct form of chronic pancreatitis that is increasingly being reported. The presentation and clinical image findings of AIP sometimes resemble those of several pancreatic malignancies, but the therapeutic strategy differs appreciably. Therefore, accurate diagnosis is necessary for cases of AIP. To date, AIP is classified into two distinct subtypes from the viewpoints of etiology, serum markers, histology, other organ involvements, and frequency of relapse: type 1 is related to IgG4 (lymphoplasmacytic sclerosing pancreatitis) and type 2 is related to a granulocytic epithelial lesion (idiopathic duct-centric chronic pancreatitis). Both types of AIP are characterized by focal or diffuse pancreatic enlargement accompanied with a narrowing of the main pancreatic duct, and both show dramatic responses to corticosteroid. Unlike type 2, type 1 is characteristically associated with increasing levels of serum IgG4 and positive serum autoantibodies, abundant infiltration of IgG4-positive plasmacytes, frequent extrapancreatic lesions, and relapse. These findings have led several countries to propose diagnostic criteria for AIP, which consist of essentially similar diagnostic items; however, several differences exist for each country, mainly due to differences in the definition of AIP and the modalities used to diagnose this disease. An attempt to unite the diagnostic criteria worldwide was made with the publication in 2011 of the international consensus diagnostic criteria for AIP, established at the 2010 Congress of the International Association of Pancreatology (IAP).

Retroperitoneal disorders associated with IgG4-related autoimmune pancreatitis

IgG4-related autoimmune pancreatitis is frequently accompanied by relevant lesions in the genitourinary tract and retroperitoneal organs, which cause various clinical problems, ranging from non-specific back pain or bladder outlet obstruction to renal failure. The diagnosis of IgG4-related retroperitoneal fibrosis requires a multidisciplinary approach, including serological tests, histological examination, imaging analysis, and susceptibility to steroid therapy. Radiological examinations are helpful to diagnose this condition, but surgical resection is occasionally unavoidable to exclude malignancy, particularly for patients with isolated retroperitoneal involvement. Steroid therapy is the treatment of choice for this condition, the same as for other manifestations of IgG4-related disease. For patients with severe ureteral obstruction, additional ureteral stenting needs to be considered prior to steroid therapy to preserve the renal function. Some papers have suggested that IgG4-related disease can affect male reproductive organs including the prostate and testis. IgG4-related prostatitis usually causes lower urinary tract symptoms, such as dysuria and pollakisuria. Patients sometimes state that corticosteroids given for IgG4-related disease at other sites relieve their lower urinary tract symptoms, which leads us to suspect prostatic involvement in this condition. Because of the limited number of publications available, further studies are warranted to better characterize IgG4-related disease in male reproductive organs.

The clinical spectrum of IgG4-related disease

IgG4-related disease (IgG4-RD) is an emerging immune-mediated disease with the capability of involving essentially any organ. The epidemiology of this disease has not been explored in detail. A majority of patients reported in the literature to date are from Japan, but the condition has been described all across the world and there is no strong evidence to suggest a predilection for Asian populations. The mean age at diagnosis is approximately 60 years and there is a decided male predominance for many clinical features, with an overall male:female ratio of 8:3. A cardinal feature of IgG4-RD is single or multiple organ swelling that often raises concern for malignancy. IgG4-RD should be suspected in patients presenting with unexplained enlargement or swelling of one or more organs. Presenting features vary substantially according to the specialty to which patients present first; in addition, the disease can be diagnosed unexpectedly in pathological specimens or identified incidentally on radiology studies. Involvement of major organs is common and IgG4-RD may lead to organ failure, particularly in the pancreas, liver and biliary tree, kidneys, thyroid gland, lungs, and aorta. The diagnosis of IgG4-RD relies on the coexistence of various clinical, laboratory and histopathological findings, although none is pathognomonic by itself.

Poor positive predictive value of serum immunoglobulin G4 concentrations in the diagnosis of immunoglobulin G4-related sclerosing disease

Background

Immunoglobulin G4 (IgG4)-related sclerosing disease is a recently described clinicopathological entity with diverse manifestations including, amongst others, autoimmune pancreatitis, sclerosing cholangitis, sclerosing sialadenitis and retroperitoneal fibrosis. Elevated serum IgG4 concentration has been described as the hallmark of this condition with reported good sensitivity and specificity.

Objective

We sought to establish the utility of serum IgG4 concentrations in the diagnosis of IgG4-related sclerosing disease by determining how many serum samples with elevated IgG4 from an unselected population would originate from patients who fulfilled criteria for this diagnosis.

Methods

The clinical features and laboratory characteristics of patients whose serum IgG4 concentration was greater than 1.30 g/L were analysed retrospectively from a total of 1,258 IgG subclass measurements performed in a tertiary hospital diagnostic laboratory.

Results

Eighty patients (6.4%) had elevated IgG4 concentrations greater than 1.30 g/L. Nine of 61 patients had the diagnosis of IgG4-related sclerosing disease, giving a poor positive predictive value of 15%. The median serum IgG4 concentrations of those with and without IgG4-related sclerosing disease were 2.16 g/L and 1.86 g/L, respectively (p = 0.22).

Conclusion

Serum IgG4 concentration has poor positive predictive value in the diagnosis of IgG4-related sclerosing disease and, therefore, the clinical significance of elevated serum IgG4 concentration alone must be interpreted with caution.

IgG4-related disease and its pathogenesis-cross-talk between innate and acquired immunity

IgG4-RD, a novel disease involving many immune-system components

IgG4-related disease (IgG4-RD) is a novel clinical entity proposed in Japan in the 21th century and is attracting strong attention over the world. The characteristic manifestations of IgG4-RD are increased serum IgG4 concentration and tumefaction by IgG4⁺ plasma cells. Although the clinical manifestations in various organs have been established, the pathogenesis of IgG4-RD is still unknown. Recently, many reports of aberrant acquired immunity such as T_h2-diminated immune responses have been published. However, many questions still remain, including questions about the pathogenesis of IgG4-RD and the roles of IgG4. In this review, we discuss the pathogenesis of IgG4-RD by focusing on the cross-talk between innate and acquired immunity.

Immunoglobulin G4-Related Retroperitoneal Fibrosis Treated with Hochuekkito, a Kampo Medicine, following Steroid Treatment

We report a case of immunoglobulin G4 (IgG4)-related retroperitoneal fibrosis (RF) with complete remission and no relapses after therapy with steroids and Hochuekkito, a Kampo (i.e. traditional Japanese herbal) medicine. A 62-year-old Japanese man was admitted to our hospital for treatment of a retroperitoneal mass detected by computed tomography. The mass had a maximum diameter of 11.0 cm; it involved the left ureter and was associated with left hydronephrosis. After inserting a ureteral stent, we performed a biopsy by laparotomy. Histopathology revealed IgG4-related RF. The lesion disappeared after 7 months of steroid therapy. We subsequently used Hochuekkito as an alternative maintenance treatment because of steroid-related complications. The patient has not relapsed in the 3 years since starting the medication. To the best of our knowledge, this is the first case of IgG4-related RF treated with Hochuekkito as a maintenance treatment.

A nationwide survey of hypertrophic pachymeningitis in Japan

OBJECTIVES

To clarify the prevalence, frequent causes and distinct features of hypertrophic pachymeningitis (HP) according to background conditions in a nationwide survey in Japan.

METHODS

The study began with a preliminary survey to determine the approximate number of HP patients diagnosed from 1 January 2005 to 31 December 2009, and was followed by a questionnaire survey for clinical and laboratory findings. HP was defined as a condition with thickening of the cranial or spinal dura mater with inflammation, evidenced by MRI or histology.

RESULTS

Crude HP prevalence was 0.949/100 000 population. The mean age at onset was 58.3±15.8 years. Among 159 cases for whom detailed data were collated, antineutrophil cytoplasmic antibody (ANCA)-related HP was found in 54 cases (34.0%) and IgG4/multifocal fibrosclerosis (MFS)-related HP in 14 cases (8.8%). Seventy cases (44.0%) were classified as 'idiopathic' and 21 (13.2%) as 'others'. ANCA-related HP cases showed a female preponderance, a higher age of onset, and higher frequencies of otological symptoms and elevated systemic inflammatory biomarkers, but lower frequencies of diplopia compared with idiopathic HP. IgG4/MFS-related HP cases showed a marked male predominance; all had cranial HP while none had isolated spinal HP or decreased sensation.

CONCLUSIONS

HP is not extremely rare. ANCA-related HP is the most frequent form, followed by IgG4/MFS-related HP. Both forms have unique features, which may help to differentiate background causes.

Recent advances in the diagnosis and management of autoimmune pancreatitis

OBJECTIVE

Autoimmune pancreatitis (AIP) is a rare chronic relapsing steroid-responsive fibroinflammatory disorder of the pancreas that is likely caused by immune dysregulation. It is now thought that AIP consists of two distinct clinicopathologic syndromes currently designated as types 1 and 2.

CONCLUSION

A current update on etiopathogenesis, pathology, and clinical and imaging findings of AIP is provided with an emphasis on diagnosis and management.

Review of the diagnosis, classification and management of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis, with as yet undetermined incidence and prevalence in the general population. Our understanding of it continues to evolve. In the last few years, 2 separate subtypes have been identified: type 1 AIP has been recognised as the pancreatic manifestation of a multiorgan disease, named immunoglobulin G4 (IgG4)-related disease while type 2 AIP is a pancreas specific disorder not associated with IgG4. International criteria for the diagnosis of AIP have been defined: the HISORt criteria from the Mayo clinic, the Japan consensus criteria and, most recently, the international association of pancreatology “International Consensus Diagnostic Criteria”. Despite this, in clinical practice it can still be very difficult to confirm the diagnosis and differentiate AIP from a pancreatic cancer. There are no large studies into the long-term prognosis and management of relapses of AIP, and there is even less information at present regarding the Type 2 AIP subtype. Further studies are necessary to clarify the pathogenesis, treatment and long-term outcomes of this disease. Critically for clinicians, making the correct diagnosis and differentiating the disease from pancreatic cancer is of the utmost importance and the greatest challenge.

IgG4-related disease

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is an immune-mediated condition that can affect almost any organ and is now being recognized with increasing frequency. IgG4-RD is characterized by a lymphoplasmacytic infiltrate composed of IgG4(+) plasma cells, storiform fibrosis, obliterative phlebitis, and mild to moderate eosinophilia. The diagnosis of IgG4-RD unifies many eponymous fibroinflammatory conditions that had previously been thought to be confined to single organs. IgG4-RD lesions are infiltrated by T helper cells, which likely cause progressive fibrosis and organ damage. IgG4 antibodies are generally regarded as noninflammatory. Although autoreactive IgG4 antibodies are observed in IgG4-RD, there is no evidence that they are directly pathogenic. Rituximab-induced B cell depletion in IgG4-RD leads to rapid clinical and histological improvement accompanied by swift declines in serum IgG4 concentrations. Although IgG autoantibodies against various exocrine gland antigens have been described in IgG4-RD, whether they are members of the IgG4 subclass is unknown. The contribution of autoantibodies to IgG4-RD remains unclear.

IgG4 plasma cell myeloma: new insights into the pathogenesis of IgG4-related disease

IgG4-related disease is a newly described systemic fibroinflammatory process, characterized by increase in IgG4-positive plasma cells. Its pathogenesis, including the role of IgG4, remains poorly understood. Plasma cell myeloma is typically associated with a large monoclonal serum spike, which is frequently of IgG isotype. We sought to identify and characterize a subset of IgG4-secreting myeloma, as it may provide a biological model of disease with high serum levels of IgG4. Six out of 158 bone marrow biopsies (4%) from patients with IgG myeloma expressed IgG4. Four patients were men and two were women, with a mean age of 64 (range 53-87) years. Imaging showed fullness of pancreatic head (1), small non-metabolic lymphadenopathy (1), and bone lytic lesions (6). Two patients developed necrotizing fasciitis. All had elevated serum M-protein (mean 2.4, range 0.5-4.2 g/dl), and none had definite signs or symptoms of IgG4-related disease. Four myelomas had plasmablastic morphology. Four had kappa and two had lambda light chain expression. Three cases expressed CD56. Two patients had a complex karyotype. In conclusion, the frequency of IgG4 myeloma correlates with the normal distribution of IgG4 isoform. The patients with IgG4 myeloma appear to have a high rate of plasmablastic morphology and could be predisposed to necrotizing fasciitis. Despite high serum levels of IgG4, none had evidence of IgG4-related disease. These findings suggest that the increased number of IgG4-positive plasma cells is not the primary etiologic agent in IgG4-related disease. Elevated serum levels of IgG4 is not sufficient to produce the typical disease presentation and should not be considered diagnostic of IgG4-related disease.

The utility of FDG-PET/CT and other imaging techniques in the evaluation of IgG4-related disease

OBJECTIVES

This study aimed to evaluate the utility of imaging techniques, including 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), in immunoglobulin (IgG)4-related disease (IgG4-RD).

METHODS

We reviewed eight IgG4-RD patients who were referred to our hospital between August 2006 and April 2012. All cases underwent FDG-PET/CT and brain magnetic resonance imaging (MRI) and endobronchial ultrasonography (EBUS) were also performed in five cases and one case, respectively.

RESULTS

Although nearly all patients with IgG4-RD in this study were negative for CRP (mean 0.22 mg/dL), various organ involvement sites were detected by FDG-PET/CT. In the active phase in two autoimmune pancreatitis (AIP) cases, FDG-PET/CT showed longitudinal and heterogeneous FDG accumulation in the pancreas with FDG uptake in the hilar or mediastinal lymph nodes. Follow-up FDG-PET/CT after therapy in one case revealed that the abnormal FDG uptake in all affected lesions had completely disappeared. In two cases, brain MRI revealed asymptomatic hypertrophic pachymeningitis. In one case, EBUS imaging of mediastinal lymph node swelling was consistent with tortuous vessels with high Doppler signals and hyperechoic strands between lymph nodes.

CONCLUSIONS

When FDG-PET/CT shows FDG accumulation, characteristic of IgG4-RD in organs, without evidence of an associated inflammatory reaction, a diagnosis of IgG4-RD can be made. Treatment effects can be assessed by the disappearance of FDG uptake. A routine brain MRI is useful for detecting asymptomatic hypertrophic pachymeningitis. EBUS may also be useful for differentiating among the etiologies of lymphadenopathy with characteristic sonographic imaging findings.

Orbital immunoglobulin-G4-related disease: case series and literature review

Immunoglobulin-G4-related disease (IgG4-RD) is a distinct group of diseases characterized by elevated serum IgG4 titres and infiltration of affected organs by IgG4-positive plasma cells. IgG4-RD can involve any ocular adnexal tissue. They have a distinct prognosis and pattern of tissue involvement and hence need to be differentiated from orbital lesions with similar clinicopathological features. We report three cases of IgG4-RD and review the literature extensively discussing various aspects of this novel entity.

Idiopathic retroperitoneal fibrosis associated with Hashimoto's thyroiditis in a patient with a single functioning kidney

Retroperitoneal fibrosis (RPF) is a rare disease characterized by the presence of fibroinflammatory tissue around the abdominal aorta and ureteral entrapment in most cases. Idiopathic RPF is frequently reported in association with autoimmune diseases; however, there have been few reports of idiopathic RPF associated with Hashimoto's thyroiditis. Here, we report a case of idiopathic RPF with Hashimoto's thyroiditis in a patient with a single functioning kidney, which was successfully treated by corticosteroid therapy and transient intraureteral stent insertion with a double-J catheter.

IgG4-Related Autoimmune Prostatitis: Is It an Unusual or Underdiagnosed Manifestation of IgG4-Related Disease?

IgG4-related disease (IgG4-RD) encompasses a wide range of extrapancreatic manifestations. Albeit some are relatively well known, others such as autoimmune prostatitis remain poorly described. We present a 61-year-old Latin-American male with autoimmune pancreatitis (AIP) who presented with lower urinary tract symptoms (LUTS), normal prostate specific antigen (PSA) test, and prostate enlargement attributed to benign prostatic hyperplasia (BPH). He underwent a transurethral resection of the prostate (TURP) after which symptoms were resolved. On histopathology, prostatic stroma had a dense inflammatory infiltrate rich in plasma cells and lymphocytes; immunohistochemical morphometric assessment showed >10 IgG4-positive plasma cells/high power field (HPF). The diagnosis of IgG4-related prostatitis was postoperatively. We compared the patient characteristics with those of previous reports on Asian patients. Shared findings included prostate enlargement, LUTS (symptoms that can be confused with BPH), and PSA within normal limits or mild elevations. IgG4-related prostatitis is rarely considered as a preprocedural diagnosis, even in patients with evidence of IgG4-RD. Involved prostate zones include mainly central and transitional zones and less frequently the peripheral. Currently, there is insufficient data about the natural history and outcome. Whether steroids, transurethral resection, or both are the treatment of choice needs to be elucidated.

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.