Clinical and pathological characteristics of Mikulicz's disease (IgG4-related plasmacytic exocrinopathy)

IgG4-Related Disease of Mastoid Presenting as Headache: A Case Report

IgG4-related disease (IgG4-RD) is a complex multi-system inflammatory disorder that can affect various organs in the body. This condition is characterized by elevated levels of immunoglobulin G subclass 4 (IgG4) and the presence of specific histopathological features. While neurological involvement is not as common as in other organs, when it occurs, it can lead to hypertrophic pachymeningitis and hypophysitis. Here, we present a case of a 53-year-old male with right-sided hemicranial headache and diplopia. Computed tomography revealed a soft tissue density lesion in the middle ear cavity and mastoid antrum with the destruction of the mastoid septae. Magnetic resonance imaging revealed a lesion in the right middle ear cavity associated with pachymeningitis and right sigmoid and transverse sinus thrombosis. Tissue pathology revealed dense plasma cell-rich chronic inflammation with storiform fibrosis. Immunohistochemistry was positive for IgG4. Hence, a diagnosis of IgG4-related disease causing mastoiditis, pachymeningitis and cerebral venous thrombosis was made. The patient was successfully operated and treated with steroids. IgG4-RD remains a rare but serious condition. It is crucial to identify and treat this condition promptly as it can lead to permanent organ damage. When patients continue to experience middle ear symptoms after an infection has been treated and cancer has been ruled out, it is important to consider inflammatory conditions as a differential diagnosis.

IgG4-related disease with massive pericardial effusion diagnosed clinically using FDG-PETCT: a case report

Background

IgG4-related disease (IgG4-RD) is a systemic inflammatory disease which involves various organs such as the pancreas, lacrimal gland, salivary gland, retroperitoneum, and so on. These organs can be affected concomitantly. 18-Fluorodeoxyglucose positron emission tomography computed tomography (FDG-PETCT) is a systemic examination which can identify active inflammation and detect multiple organ involvement simultaneously. Pericardial involvement is rare in IgG4-RD, early detection and treatment can greatly improve the prognosis of patients.

Case summary

We reported a 82-year-old female patient referred to our department complaining of chest tightness and abdominal fullness for 8 months and massive pericardial effusion for 2 months. A large amount of pericardial effusion was found during the hospitalization of Gastroenterology. Then she was transferred to cardiology. Although infectious, tuberculous, and neoplastic pericardial effusions were excluded, there was still no diagnosis. The patients were examined by FDG-PETCT which considered IgG4-RD. After coming to our department, the results of the patient's laboratory tests showed that immunoglobulin subgroup IgG4 was 14.0 g/L. Then we performed a biopsy of the right submandibular gland. Pathological morphology and immunohistochemistry suggested IgG4-RD. Combined with level of IgG4, clinical, pathological and immunohistochemical results, we determined the final diagnosis of IgG4 related diseases. Then we gave glucocorticoid and immunosuppressant treatment. At the end, pericardial effusion was completely absorbed. As prednisone acetate was gradually reduced, no recurrence of the disease has been observed.

Conclusion

Pericardial effusion can be the initial presentation in IgG4-RD. For patients with massive pericardial effusion of unknown cause, early detection of IgG4 is recommended, and PETCT may be helpful for obtaining the diagnosis.

Primary Sjögren's syndrome misdiagnosed as Mikulicz's disease: a case report

BACKGROUND

Sjögren's Syndrome (SS) is an inflammatory autoimmune disease, and Mikulicz's disease (MD) is a lymphoproliferative disorder. Both MD and SS are more common in middle-aged female, and the dry eyes could be presented in both of them with different degree. The MD patients are characterized by symmetrical swelling of the lacrimal glands which also can occur in the early stage of SS. And the imaging findings between early stage of SS and MD are lack of specificity. Therefore, SS and MD have similarities in the clinical manifestations, imaging and pathological findings and are confused in diagnosis.

CASE PRESENTATION

A 51-year-old female patient presented with bilateral swelling of the upper eyelids for 2 years. She also reported having dry mouth and dry eyes which could be tolerated. The Schirmer's test result is positive and the laboratory tests indicate serum total IgG increased. In the bilateral lacrimal gland area could palpate soft masses. The orbital magnetic resonance imaging (MRI) examination showed bilateral lacrimal gland prolapse. While the histopathological result was considered as MD. The immunohistochemical (IHC) staining results were positive for IgG and negative for IgG4. To clarify the diagnosis, SS-related laboratory tests were performed: anti-SSA antibody (+++), anti-SSB antibody (+++), anti-Ro-52 antibody (+++). With a comprehensive consideration, the final diagnosis was SS.

CONCLUSION

When the clinical manifestations are atypical, it is necessary to pay attention to the differential diagnosis of SS and MD.

Missing link between tissue specific expressing pattern of ERβ and the clinical manifestations in LGBLEL

Purpose

Lacrimal gland benign lymphoepithelial lesion (LGBLEL) is an IgG4-related disease of unknown etiology with a risk for malignant transformation. Estrogen is considered to be related to LGBLEL onset.

Methods

Seventy-eight LGBLEL and 13 control clinical samples were collected and studied to determine the relationship between estrogen and its receptors and LGBLEL development.

Results

The serological analysis revealed no significant differences in the levels of three estrogens be-tween the LGBLEL and control groups. However, immunohistochemical analyses indicated that the expression levels of ERβ and its downstream receptor RERG were relatively lower in LGBLEL samples than in control samples, with higher expression in the lacrimal gland and lower expression in the lymphocyte infiltration region. However, low expression of ERα was detected. The transcriptome sequence analysis revealed upregulated genes associated with LGBLEL enriched in lymphocyte proliferation and activation function; downregulated genes were enriched in epithelial and vascular proliferation functions. The key genes and gene networks were further analyzed. Interactions between B cells and epithelial cells were analyzed due to the identified involvement of leukocyte subsets and epithelial cells. B cell proliferation was found to potentially contribute to lacrimal gland apoptosis.

Conclusion

Therefore, the tissue-heterogeneous expression pattern of ERβ is potentially related to the clinical manifestations and progression of LGBLEL, although further investigations are required to confirm this finding.

T Cell Roles and Activity in Chronic Sclerosing Sialadenitis as IgG4-Related Disease: Current Concepts in Immunopathogenesis

IgG4-related disease is a multiorgan immunological fibroinflammatory disorder characterized by lymphoplasmacytic infiltration and fibrosis in multiple organs accompanied by high serum IgG4 levels. The salivary glands are the most common organs involved in this disease. Recently, chronic sclerosing sialadenitis affecting salivary glands, formerly known as Küttner's tumor, and Mikulicz's disease have been classified as a class of IgG4-related diseases. The etiopathobiology of IgG4-related disease is not fully understood. It has recently been hypothesized that the inflammatory and fibrotic process and the increased serum IgG4⁺ levels in IgG4-related disease are the result of an interaction between B cells and T helper cells, suggesting that T cells may play a key role in the pathogenesis of this disease. The aim of this review is to discuss the proposed roles of different T cell subsets in the pathogenesis of IgG4-related disease focusing on their roles in immunopathogenesis of IgG4-related sialadenitis.

Activation of Mast-Cell-Derived Chymase in the Lacrimal Glands of Patients with IgG4-Related Ophthalmic Disease

The purpose of this present study was to investigate the distribution and expression of chymase in the lacrimal glands (LGs) of patients afflicted with IgG4-related ophthalmic disease (IgG4-ROD). LGs from patients with severe canalicular obstruction were considered the control group. Toluidine blue staining confirmed a significant increase in the number of mast cells in the LGs obtained from the IgG4-ROD patients. In addition, immunostaining of serial sections from the LGs showed a significant increase in the number of chymase-positive cells and tryptase-positive cells in the IgG4-ROD LGs compared to the normal control LGs. The mRNA expression of chymase, tryptase, TGF-β1, and collagen-I tended to increase in the IgG4-ROD LGs. Immunostaining of vimentin and α-smooth muscle actin (α-SMA) showed that myofibroblasts were the main cellular components in severely fibrotic regions of LGs in patients with IgG4-ROD. Linear regression analyses on the number of mast cells, chymase-positive cells, and tryptase-positive cells revealed significant positive correlations between those respective cells. Our findings suggest that chymase may play a role in the fibrotic disorder of IgG4-ROD LGs through the regulation of TGF-β1 activation and collagen-I deposition, and that it may be a therapeutic target for patients afflicted with IgG4-ROD.

The Role of IgG4 in Autoimmunity and Rheumatic Diseases

The distinguishing of the IgG4-related disease (IgG4-RD) from among other rheumatic diseases has brought attention to the IgG4 subclass of immunoglobulins. It is the least numerous subclass among immunoglobulins G. In general, IgG4 is considered to be non-inflammatory and tolerance inducing, due to its unique structure. However, in IgG4-RD this antibody plays a pathogenic role in activation of the fibrinogenesis and of the inflammatory process; there are also suggestions that it may be a marker of an abnormal inflammatory response. The importance of IgG4 for the pathogenesis of allergic diseases, with a vital role of its ratio to immunoglobulin E (IgE/IgG4 ratio), has been known for years. The role of IgG4 in the course and pathogenesis of rheumatic diseases is still being researched and is not yet fully understood. Increased IgG4 levels have been revealed in rheumatoid arthritis, although no clear link between this phenomenon and disease activity has been demonstrated. There are articles on the potential importance of IgG4 concentration (of both elevated and decreased serum levels) in Sjogren’s syndrome. Additionally, anti-nuclear IgG4 antibody significant titers have been detected in SLE patients, and it has been suggested that the effect of these antibodies on complement consumption and the production of proinflammatory cytokines may play a role in inhibiting the progression of SLE. IgG4 plays a role in autoimmune diseases other than rheumatic diseases, such as pemphigus, bullous pemphigoid, idiopathic membranous glomerulonephritis, or myasthenia gravis, but also in helmints infections. Research shows the importance of IgG4 in malignancy of neoplasms. Melanoma cells are known to stimulate IgG4 production through a modified Th2-based inflammatory response. The role of this immunoglobulin in cholangiocarcinoma is also considered as possible. The aim of this review article is to discuss the current knowledge of IgG4 not only from the perspective of the IgG4-RD but also from a point of view of other autoimmune diseases with particular emphasis on rheumatic diseases.

[Immunoglobulin G (IgG) 4-related diseases]

Immunoglobulin G (IgG) 4‑related diseases are fibrosing inflammatory systemic diseases that can affect almost every organ system. Typical disease manifestations include autoimmune pancreatitis, lymphadenopathy, retroperitoneal fibrosis, inflammatory orbitopathy and involvement of the salivary and lacrimal glands. Organ involvements can occur either isolated or in combination with other disease manifestations. Before diagnosing IgG4-related diseases, malignancies and other inflammatory diseases have to be excluded. The diagnosis requires a combination of laboratory findings, histological and radiological results. Typically, IgG4-related diseases respond well to glucocorticosteroids. In cases of relapse or severe organ involvement a longer term immunosuppression is often required, whereas watch and wait can also be sufficient in milder cases.

Olfactory dysfunction in LATY136F knock-in mice

OBJECTIVE

This study examined olfactory dysfunction in LATY136F knock-in mice and its pathogenic mechanism.

METHODS

The olfactory function of LATY136F knock-in mice was assessed by a behavioral test using cycloheximide solution, which has been used as a mice repellant because of its peculiar smell and unpleasant taste. The tests were administered to each group of LATY136F knock-in mice and WT mice at 8, 12, 16, 20, and 24 weeks of age. After the behavioral tests to evaluate olfactory function, the mice were sacrificed for evaluations by immunohistochemistry.

RESULTS

Behavioral tests to evaluate olfactory function showed that the LATY136F knock-in mice had a statistically significant level of olfactory dysfunction (P < 0.05). Histological analysis showed that the thickness of the olfactory epithelium in these mice was thinner than that in the age-matched wild type mice. There was no IgG4-RD like lesion in the olfactory epithelium of LATY136F knock-in mice. Olfactory marker protein and growth-associated protein 43 expressions in the olfactory epithelium of the LATY136F knock-in mice were markedly lesser than those in the wild type mice (P < 0.05).

CONCLUSION

The present study demonstrated that olfactory disturbances occurred in LATY136F knock-in mice. Furthermore, the mechanism was suggested to be reduced regeneration of the olfactory epithelium.

Imaging of IgG4-related disease in the extracranial head and neck

PURPOSE

Immunoglobulin G4-related disease (IgG4-RD) is a newly defined fibro-inflammatory multisystemic condition defined by a triad of diagnostic criteria based on clinical presentation, biochemical and histopathological findings. Whereas some subsites of this disease have been well described in the literature so far (e.g. pancreas, kidneys, retroperitoneum, salivary glands), more recently identified anatomical sites of involvement in the head and neck are less well understood (e.g. nose, paranasal sinuses).

METHOD

This pictorial review details the imaging appearances of extracranial IgG4-RD in the Head & Neck. Multimodality imaging appearance and features are presented, with reference to the published literature to date.

RESULTS

Following a subsite-based approach, we present both the most common and the more rarely encountered imaging patterns of IgG4-RD in the extracranial head and neck, along with the relevant differential diagnoses to consider. Our institutional experience not only cements what is already known in the existing literature on this topic, but also reveals new imaging features of IgG4-RD, notably in the sinonasal tract.

CONCLUSIONS

This pictorial review of extracranial head & neck IgG4-RD will enable radiologists to recognise the features of this condition and propose it as a differential diagnosis to include alongside other probable entities. It establishes the place of the radiologist in the diagnosis and management of IgG4-RD.

Review of a novel disease entity, immunoglobulin G4-related disease

Immunoglobulin G4 (IgG4)-related dacryoadenitis and sialoadenitis (IgG4-DS) are part of a multiorgan fibroinflammatory condition of unknown etiology termed IgG4-related disease (IgG4-RD), which has been recognized as a single diagnostic entity for less than 15 years. Histopathologic examination is critical for diagnosis of IgG4-RD. CD4+ T and B cells, including IgG4-expressing plasma cells, constitute the major inflammatory cell populations in IgG4-RD and are thought to cause organ damage and tissue fibrosis. Patients with IgG4-RD who have active, untreated disease exhibit significant increase of IgG4-secreting plasmablasts in the blood. Considerable insight into the immunologic mechanisms of IgG4-RD has been achieved in the last decade using novel molecular biology approaches, including next-generation and single-cell RNA sequencing. Exploring the interactions between CD4+ T cells and B lineage cells is critical for understanding the pathophysiology of IgG4-RD. Establishment of pathogenic T cell clones and identification of antigens specific to these clones constitutes the first steps in determining the pathogenesis of the disease. Herein, the clinical features and mechanistic insights regarding pathogenesis of IgG4-RD were reviewed.

IgG4-related small-sized occlusive vasculitis in Mikulicz's disease

Mikulicz's disease is one of the IgG4-related diseases (IgG4-RDs) that involves the cardiovascular system; however, small-sized vasculitis is rare in IgG4-related diseases. A 64-year-old man presented with distal occlusive disease and developed left cerebrovascular infarction with occlusion of the middle cerebral artery and diseased temporal artery branches. He underwent superficial temporal artery-middle cerebral artery anastomosis surgery. Histology of the temporal artery biopsy showed smooth muscle cell proliferation with many IgG4-positive plasma cells. He then developed salivary gland inflammation, and Mikulicz's disease was diagnosed. Small-sized occlusive vasculitis was observed in this IgG4-RD. Low-dose corticosteroid therapy is effective in preventing progressive occlusive disease.

IgG4-Related Disease with Emphasis on Its Gastrointestinal Manifestation

IgG4-related disease is an immune-mediated fibroinflammatory condition with a diverse spectrum of organ involvement, commonly in the pancreas and bile ducts among other organs such as salivary and lacrimal glands. Classic histopathologic findings are the gold standard for confirmation of diagnosis, although diagnosis remains challenging, as biomarkers to date are neither sufficient nor necessary. Glucocorticoids are the most effective initial treatment, generally having a dramatic response, although limited clinical evidence exists regarding effective maintenance therapy. This review summarizes key GI manifestations of this condition for the practicing gastroenterologist and addresses the pathology, disease mechanism, and current therapeutic recommendations.

Dental-craniofacial manifestation and treatment of rare diseases

Rare diseases are usually genetic, chronic and incurable disorders with a relatively low incidence. Developments in the diagnosis and management of rare diseases have been relatively slow due to a lack of sufficient profit motivation and market to attract research by companies. However, due to the attention of government and society as well as economic development, rare diseases have been gradually become an increasing concern. As several dental-craniofacial manifestations are associated with rare diseases, we summarize them in this study to help dentists and oral maxillofacial surgeons provide an early diagnosis and subsequent management for patients with these rare diseases.

Clinical features and mechanistic insights regarding IgG4-related dacryoadenitis and sialoadenitis: a review

Immunoglobulin G4-related disease (IgG4-RD), recognized only recently as a single diagnostic entity, is a chronic inflammatory condition of unknown etiology. The diagnosis of IgG4-RD relies heavily on histopathological analysis and the correlation of histology findings with clinical, serological, and radiological data. CD4⁺ T and B cells, including IgG4-expressing plasmablasts, constitute the major inflammatory cell populations in IgG4-RD and are believed to cause organ damage and tissue fibrosis. Patients with IgG4-RD, who have active, untreated disease, exhibit marked expansion of IgG4-secreting plasmablasts in the blood. Important mechanistic insights correlated with the pathogenesis of IgG4-RD have been disclosed in recent years through the application of novel molecular biology approaches, including next-generation and single-cell RNA sequencing. Exploration of the interactions between these CD4⁺ T cells and cells of the B lymphocyte lineage is critical to understanding the pathophysiology of IgG4-RD. The establishment of pathogenic T cell clones and the identification of antigens specific to these clones constitute the first steps in determining the pathogenesis of this disease. This review focuses on clinical features and mechanistic insights regarding IgG4-related dacryoadenitis and sialoadenitis, from a perspective suitable for oral and maxillofacial surgeons.

A Series of Biopsy-proven Patients with Immunoglobulin G4-related Neurological Disease

Aim:

To study the clinical presentation, radiological findings, and therapy responsiveness of patients with biopsy-proven immunoglobulin G4 (IgG4)-related neurological disease.

Methods:

The study was conducted between January 2016 and March 2018 from the Department of Neurology and Pathology of Nizam's Institute of Medical Sciences. Patients with neurological symptoms and biopsy suggestive of IgG4-related disease (IgG4-RD) were included. These patients were studied for their demographic pattern and clinical presentation. The presence of serological markers such as vasculitic profile and IgG4 levels was analyzed. Radiological findings were studied in detail. Therapeutic agents used and the response to therapy were assessed.

Results:

There were six cases with IgG4-related neurological disease which were all hypertrophic pachymeningitis. The age ranged from 35 to 64 (mean = 46) years. The clinical presentation was acute in one, subacute in two, and chronic in three patients. The most common presenting symptom was headache (4), followed by gait and/or urinary disturbances (2), paraparesis (1), and diplopia (1). IgG4 levels were elevated in 50% of them. Pseudotumor-like mass and sinovenous thrombosis, not described previously, were seen in one patient. All the patients were treated with oral or intravenous steroid. Rituximab was given in three patients; azathioprine was the steroid-sparing agent in one patient. Those with acute/subacute onset of presentation had an excellent response to steroids. All the patients with a chronic duration of their symptoms received empirical anti-tuberculous therapy before a definitive diagnosis of Ig G4-RD was made.

Conclusions:

The characterization of patients with IgG4-related neurological disease based on the understanding of the clinical spectrum increases the confidence in the clinician to resort to early immunosuppression, thereby having prognostic implications.

Macrophage migration inhibitory factor contributes to the pathogenesis of benign lymphoepithelial lesion of the lacrimal gland

Background

Benign Lymphoepithelial Lesion (BLEL) is a rare disease observed in the adult population. Despite the growing numbers of people suffering from BLEL, the etiology and mechanisms underlying its pathogenesis remain unknown.

Methods

In the present study, we used gene and cytokines expression profiling, western blot and immunohistochemistry to get further insight into the cellular and molecular mechanisms involved in the pathogenesis of BLEL of the lacrimal gland.

Results

The results showed that Macrophage Migration Inhibitory Factor (MIF) was the most highly expressed cytokine in BLEL, and its expression positively correlated with the expression of Th2 and Th17 cells cytokines. MIF was found to regulate biological functions and pathways involved in BLEL pathogenesis, such as proliferation, resistance to apoptosis, MAPK and PI3K/Akt pathways. We also found that MIF promotes fibrosis in BLEL by inducing BLEL fibroblast differentiation into myofibroblasts as well as the synthesis and the deposit of extracellular matrix in BLEL tissues.

Conclusions

Our findings demonstrate the contribution of MIF to the pathogenesis of BLEL of the lacrimal gland and suggested MIF as a promising therapeutic target for its treatment.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0284-4) contains supplementary material, which is available to authorized users.

IgG4-related retroperitoneal fibrosis overlapping with primary biliary cirrhosis and primary Sjögren's syndrome: A case report

RATIONALE

IgG4-related disease (IgG4-RD) is a chronic fibro-inflammatory disorder which is characterized by elevated levels of serum IgG4 and infiltration of IgG4-bearing plasma cells in the involved organs. Primary biliary cirrhosis (PBC) and Primary Sjögren's syndrome (pSS) are both distinct from IgG4-related disease. We herein describe a Chinese patient with IgG4-related RPF overlapping with PBC and pSS.

PATIENT CONCERNS

We report a case of 69-year-old male with recurrent lower abdominal pain for 10 months. Laboratory data showed elevated erythrocyte sedimentation rate and hepatobiliary enzymes, renal dysfunction, high titers of antinuclear antibody, anti-SS-A antibody and anti-mitochondrial type 2, high immunoglobulin (Ig) G levels and elevated serum IgG4 (9 g/L). Contrast-enhanced computed tomography and magnetic resonance imaging were suggestive of retroperitoneal fibrosis and unilateral ureteral occlusion. Immunohistochemical staining for IgG4 did not demonstrate infiltration of IgG4-positive plasma cells in the retroperitoneal mass, but revealed significant infiltration of lymphocytoplasma cells as well as fibrosis and fibrin accumulation.

DIAGNOSES

The patient was diagnosed with IgG4-related retroperitoneal fibrosis based on the International Consensus Diagnostic Criteria. He was also diagnosed with primary biliary cirrhosis and primary Sjögren's syndrome.

INTERVENTIONS

250 mg ursodeoxycholic acid was administered twice daily, and prednisolone was initiated at a dose of 40 mg/day and then tapered to 25 mg after 45 days.

OUTCOMES

The size of the retroperitoneal soft tissue mass gradually reduced and the abnormal laboratory parameters were restored to normal.

LESSONS

This rare clinical condition has seldom been reported in the literature, which suggests that common immunogenetic factors may be involved in the development of IgG-related RPF, PBC and pSS.

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.

Genes and pathways associated with the occurrence of malignancy in benign lymphoepithelial lesions

There is increasing evidence concerning the occurrence of malignant lymphoma among people suffering from Mikulicz disease, also termed benign lymphoepithelial lesion (BLEL) and immunoglobulin G4-associated disease. However, the underlying molecular mechanism of the malignant transformation remains unclear. The present study aimed to investigate the gene expression profile between BLEL and malignant lymphoepithelial lesion (MLEL) conditions using tissue microarray analysis, to identify genes and pathways which may be associated with the risk of malignant transformation. Comparing gene expression profiles between BLEL tissues (n=13) and MLEL (n=14), a total of 1,002 differentially expressed genes (DEGs) were identified including 364 downregulated and 638 upregulated DEGs in BLEL. The downregulated DEGs in BLEL were frequently associated with immune-based functions, immune cell differentiation, proliferation and survival, and metabolic functions, whereas the upregulated DEGs were primarily associated with organ, gland and tissue developmental processes. The B cell receptor signaling pathway, the transcription factor p65 signaling pathway, low affinity immunoglobulin γ Fc region receptor II-mediated phagocytosis, the high affinity immunoglobulin ε receptor subunit γ signaling pathway and Epstein-Barr virus infection, and pathways in cancer, were the pathways associated with the downregulated DEGs. The upregulated DEGs were associated with three pathways, including glutathione metabolism, salivary secretion and mineral absorption pathways. These results suggested that the identified signaling pathways and their associated genes may be crucial for understanding the molecular mechanisms underlying malignant transformation from BLEL, and they may be considered to be markers for predicting malignancy among the BLEL group.

IgG4-related intraocular inflammation masquerading as ciliary body melanoma in a young girl

Immunoglobulin G4 (IgG4-related diseases) affects various tissues and organs of the human body. Orbital, adnexal, and scleral inflammations were already reported in the medical literature. To the best of our knowledge, we report the first case of intraocular IgG4-associated inflammatory mass in the ciliary body mimicking as a melanoma in a 23-year-old female from Northeast India. Characteristic histopathology, immunohistochemistry in the tissue, protein chemistry, and raised serum IgG4 were supportive for the diagnosis. As this newly diagnosed disease has multi-organ affection and little is known about its pathogenesis particularly in eye and adnexa, the present case will open many challenges in clinico-pathological diagnosis and research in the future.

Imaging of IgG4-related disease of the head and neck

IgG4-related disease is a systemic, inflammatory disorder typically involving multiple organ systems. Several eponymous conditions described previously in the clinical and radiology literature are now recognised to be part of the IgG4-related disease spectrum. This includes multiple manifestations in the head and neck region, which are the subject of this review. Imaging can occasionally suggest the specific diagnosis of IgG4 disease. More commonly, it will be included in a limited differential diagnosis that requires clarification with the aid of image-guided biopsy. There are strict histopathological criteria for the diagnosis of IgG4-related disease.

[Swelling of the submandibular and parotid glands : A description of possible differential diagnoses]

Swelling of single or multiple major salivary glands can be caused by various local or systemic diseases. In differential diagnosis, congenital cystic or vascular malformations should be considered, as well as infectious or tumorous alterations. Salivary duct obstructions due to sialolithiasis or stenosis can cause salivary gland enlargement. Multiple systemic diseases can have manifestations in the parotid or submandibular glands. As therapy varies from cause to cause, knowledge of the different potential diagnoses is crucial.

Interleukin-33 produced by M2 macrophages and other immune cells contributes to Th2 immune reaction of IgG4-related disease

IgG4-related disease (IgG4-RD) is characterized by elevated serum IgG4 and marked infiltration of IgG4-positive cells in multiple organs. Interleukin-33 (IL-33) is a recently described cytokine that is secreted by damaged epithelial cells, macrophages, and dendritic cells, and potently activates helper T type 2 (Th2) immune responses, which have been suggested to play a major role in IgG4 production of IgG4-RD. Here, we assessed the expression of IL-33 and related molecules in the salivary glands (SGs) of patients with IgG4-RD versus that in patients with Sjögren's syndrome (SS) and controls. Expression of IL-33 and its receptor (ST2) was strongly detected around ectopic germinal centers (GCs) in the SGs from patients with IgG4-RD, whereas IL-33 was expressed only in epithelial cells in patients with SS and controls. Moreover, IL-33 and CD68⁺/CD163⁺ macrophages were mainly distributed around ectopic GCs in patients with IgG4-RD. Double immunofluorescence staining showed that IL-33 expression co-localized with CD68⁺/CD163⁺ macrophages. Finally, mRNA expression levels of IL-33 showed a positive correlation to those of Th2 cytokines (IL-4 and IL-13) in patients with IgG4-RD. Our data suggest that IL-33 produced by M2 macrophages might contribute to the pathogenesis of IgG4-RD via aberrant activation of Th2 immune responses.

Lesional CD4+ IFN-γ+ cytotoxic T lymphocytes in IgG4-related dacryoadenitis and sialoadenitis

OBJECTIVES

IgG4-related disease (IgG4-RD) is a chronic, systemic, inflammatory condition of unknown aetiology. We have recently described clonally expanded circulating CD4+ cytotoxic T lymphocytes (CTLs) in IgG4-RD that infiltrate affected tissues where they secrete interleukin (IL)-1β and transforming growth factor -β1 (TGF-β1). In this study, we sought to examine the role of CD4+ CTLs in the pathogenesis of IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS) and to determine whether these cells secrete interferon-gamma (IFN-γ) at lesional sites.

METHODS

Salivary glands of 25 patients with IgG4-DS, 22 patients with Sjögren's syndrome (SS), 12 patients with chronic sialoadenitis (CS) and 12 healthy controls were analysed in this study. Gene expression analysis was performed on submandibular glands (SMGs) from five patients with IgG4-DS, three with CS and three healthy controls. Infiltrating CD4+ CTLs were examined by quantitative multicolour imaging in tissue samples from 20 patients with IgG4-DS, 22 patients with SS, 9 patients with CS and 9 healthy controls.

RESULTS

In IgG4-DS tissues, nine genes associated with CD4+ CTLs were overexpressed. The expression of granzyme A (GZMA) mRNA was significantly higher in samples from patients with IgG4-RD compared with corresponding tissues from SS and healthy controls. Quantitative imaging showed that infiltrating CD4+ GZMA+ CTLs were more abundant in patients with IgG4-DS than in the other groups. The ratio of CD4+GZMA+ CTLs in SMGs from patients with IgG4-DS correlated with serum IgG4 concentrations and the number of affected organs. A large fraction of CD4+GZMA+ CTLs in SMGs from patients with IgG4-DS secreted IFN-γ.

CONCLUSIONS

The pathogenesis of IgG4-DS is associated with tissue infiltration by CD4+GZMA+ CTLs that secrete IFN-γ.

Differential diagnosis of IgG4-related sialadenitis, primary Sjögren syndrome, and chronic obstructive submandibular sialadenitis

Our aim was to differentiate IgG4-related sialadenitis, primary Sjögren syndrome, and chronic obstructive submandibular sialadenitis by analysing clinical, radiographic, and pathological features. Fifty-five patients, 50, and 50 were enrolled, respectively and their baseline characteristics and serological, sialographic, and pathological findings compared. The male:female ratio for IgG4-related sialadenitis was 1:1.2 for primary Sjögren syndrome 1:15.7, and for chronic obstructive submandibular sialadenitis1:0.92. Numbers with enlarged salivary glands were 55, 16, and 50; with xerostomia 26, 48, and 0; with a history of allergy 26, 4, and 6, and with coexisting systemic disease 12, 19, and 0 (p=0.14). Mean (SD) serum IgG4 concentrations were 109.1 (97.9), 4.9. (1.9) g/L, and 5.3 (1.6) g/L, p<0.001 in all cases. Sialography showed enlargement of the gland, dilatation of the duct, and slightly decreased secretory function in IgG4-related disease; obvious sialectasia and decreased secretory function in Sjögren syndrome; and dilatation of Wharton's duct and filling defects in obstructive sialadenitis. Histopathological examination showed lymphoplasmacytic infiltration with storiform fibrosis, lymphoplasmacytic inflammation and lymphoepithelial lesions, and dilatation of the duct with epithelial metaplasia in the three groups, respectively. The number of IgG4-positive plasma cells was 123 (45)/HPF, 8 (3)/HPF, and 5 (4)/HPF, while the IgG4-/IgG-positive cell ratio was 71.7 (13.9)%, 4.6 (2.5)%, 18.9 (19.7)%, respectively (p<0.001). The three conditions have different clinical, radiographic, and pathological features that provide important clues to the differential diagnosis. Serological and histological tests are important, and comprehensive consideration is necessary.

Enhanced IgG4 production by follicular helper 2 T cells and the involvement of follicular helper 1 T cells in the pathogenesis of IgG4-related disease

Background

The aim of this study was to elucidate the function of circulating follicular helper T (Tfh) cell subsets in helping B cells in patients with active, untreated IgG4-related disease (IgG4-RD) and determine their relationship with disease activity.

Methods

Seventeen consecutive patients with active, untreated IgG4-RD, 20 with primary Sjögren syndrome (pSS), 5 with multicentric Castleman’s disease (MCD), and 12 healthy controls (HC) were enrolled. Tfh cell subset function was evaluated by co-culture with naïve B cells in vitro. Activated Tfh cell subsets were defined as a CCR7^lowPD-1^high subset among Tfh cell subsets. Disease activity was evaluated by IgG4-RD responder index (IgG4-RD RI) score.

Results

The number of Tfh2 cells was significantly higher in IgG4-RD compared to pSS, MCD, or HC, and correlated with serum IgG4 level or the number of plasmablasts. In vitro, Tfh2 cells more efficiently induced the differentiation of naïve B cells into plasmablasts compared to Tfh1 or Tfh17 cells. Of note, while IgG production in culture supernatants of Tfh2 cells was comparable between IgG4-RD and HC, IgG4 production was significantly higher with Tfh2 cells from patients with IgG4-RD than in those from HC. Accordingly, the IgG4:IgG ratio in culture supernatants was also significantly higher with Tfh2 cells from IgG4-RD compared to HC. Moreover, the number of activated Tfh2 cells was higher in IgG4-RD compared to pSS, MCD, or HC, and strongly correlated with IgG4-RD RI score in the baseline active phase. Particularly, the number of activated Tfh2 cells was associated with the number of affected organs and serum IgG4 level. Importantly, the number of activated Tfh2 cells was decreased after glucocorticoid treatment and paralleled disease improvement. Moreover, the number of activated Tfh1 cells was also increased in IgG4-RD compared to pSS, MCD, or HC, correlating with IgG4-RD RI score, but not with serum IgG4 level.

Conclusions

Tfh2 cells, but not Tfh1 or Tfh17 cells, induce the differentiation of naïve B cells into plasmablasts and enhanced production of IgG4 in patients with active, untreated IgG4-RD. Furthermore, activated Tfh2 cells reflect disease activity, suggesting the involvement of this T cell subset in the pathogenesis of IgG4-RD. Interestingly, the number of activated Tfh1 cells was also increased in IgG4-RD, correlating with disease activity but not with serum IgG4 level, suggesting the involvement of Tfh1 cells but not in the process of IgG4 production in patients with IgG4-RD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1064-4) contains supplementary material, which is available to authorized users.

Non-infectious environmental antigens as a trigger for the initiation of an autoimmune skin disease

Pemphigus represents a group of organ specific autoimmune blistering disorders of the skin mediated by pathogenic autoantibodies with well-defined antigenic targets. While most of these diseases are sporadic, endemic forms of disease do exist. The endemic form of pemphigus foliaceus (also known as fogo selvagem, FS) exhibits epidemiological features that suggest exposure to hematophagous insect bites are a possible precipitating factor of this autoimmune disease, and provides a unique opportunity to study how environmental factors contribute to autoimmune disease development. FS patients and healthy individuals from endemic regions show an autoreactive IgM response that starts in early childhood and becomes restricted to IgG4 autoantibodies in FS patients. In searching for triggering environmental antigens, we have found that IgG4 and IgE autoantibodies from FS patients cross-react with a salivary antigen from sand flies. The presence of these cross-reactive antibodies and antibody genetic analysis confirming that these antibodies evolve from the same naïve B cells provides compelling evidence that this non-infectious environmental antigen could be the initial target of the autoantibody response in FS. Consequently, FS serves as an ideal model to study the impact of environmental antigens in the development of autoimmune disease.

Estimation of the number of histological diagnosis for IgG4-related kidney disease referred to the data obtained from the Japan Renal Biopsy Registry (J-RBR) questionnaire and cases reported in the Japanese Society of Nephrology Meetings

Background

More than 2 years have passed since the proposal of the diagnostic criteria for IgG4-related kidney disease (IgG4-RKD). The aim of this study was to estimate the number of histological diagnosis for IgG4-RKD throughout Japan and to clarify the regional distribution of the development of this disease.

Methods

A questionnaire was supplied to 140 research facilities registered in the Japan Renal Biopsy Registry (J-RBR). The items of the questionnaire were the total number of renal biopsies performed and the number of cases diagnosed as IgG4-RKD in 2012 and 2013 at each facility. Age, sex, and diagnosis category were also included for the IgG4-RKD cases. The geographic distribution of the disease development was evaluated using clinical case reports presented at the Eastern/Western regional meeting of the Japanese Society of Nephrology during the 15 years following 2001.

Results

Forty-seven facilities completed the questionnaire, resulting in a collection rate of 34 %. The total numbers of renal biopsies in 2012 and 2013 were 3387 and 3591, respectively. Forty-seven of these cases (24 in 2012 and 23 in 2013) were diagnosed as IgG4-RKD. The frequency of development of IgG4-RKD per one million over 40-year-old individuals during these 15 years varied between 0.9 and 3.1, depending on Japanese geographic region of Japan.

Conclusion

The results of the present survey indicate that the number of diagnosis for IgG4-RKD is approximately 130 cases per year throughout Japan, and no regional differences in disease frequency appear to exist.

DNA Microarray Analysis of Submandibular Glands in IgG4-Related Disease Indicates a Role for MARCO and Other Innate Immune-Related Proteins

IgG4-related disease (IgG4-RD) is a novel systemic disease entity characterized by elevated serum IgG4 and tissue infiltration of IgG4-positive plasma cells accompanied by severe fibrosis. Although recent studies demonstrated that innate immune cells including monocytes and macrophages might promote local fibrosis and IgG4 production, the pathological mechanism remains unclear. In this study, we sought to identify the disease-associated genes, especially innate immune molecules. Gene expression was analyzed by DNA microarray in submandibular glands (SMGs) from patients with IgG4-RD (n = 5), chronic sialoadenitis (CS) (n = 3), and controls (n = 3). Differentially expressed genes (DEGs) were validated by real-time polymerase chain reaction (PCR) and immunohistochemical staining in IgG4-RD (n = 18), CS (n = 4), Sjögren syndrome (n = 11), and controls (n = 10). Gene expression patterns in the 3 groups were quite different from each other by the pvclust method and principal components analysis. In IgG4-RD, 1028 upregulated genes and 692 downregulated genes were identified as DEGs (P < 0.05). Gene Ontology (GO) term analysis indicated that the upregulated DEGs in IgG4-RD encoded proteins involved in T/B cell activation and chemotaxis. PCR validated significantly higher expression of macrophage receptor with collagenous structure (MARCO), a pattern-recognition receptor, in IgG4-RD compared with the other groups (P < 0.01). Immunohistochemical analysis confirmed that the expression pattern of MARCO was similar to that of the M2 macrophage marker CD163. MARCO was identified as a disease-associated molecule in IgG4-RD by DNA microarray. Moreover, M2 macrophages might contribute to the initiation of IgG4-RD via MARCO.

Overlapping IgG4 Responses to Self- and Environmental Antigens in Endemic Pemphigus Foliaceus

The etiology of human autoimmune diseases in general remains largely unknown, although the genetic and environmental interplay may be relevant. This applies to the autoimmune diseases of the skin such as the pemphigus phenotypes and others. In this group, there is an endemic form of pemphigus foliaceus (also known as fogo selvagem [FS]) in which the pathogenic IgG4 autoantibody response to the self-antigen desmoglein 1 (Dsg1) cross-reacts with the LJM11 sand fly salivary gland Ag. In this investigation, we dissected the IgG4 autoantibody repertoires used by FS patients in response to endogenous self-Dsg1 and exogenous LJM11 sand fly Ag. Based on analyses of the genetic clonal signatures of these Abs, our results indicate that there is a significant overlap between these two responses, as all identified IgG4 mAbs cross-react to both Dsg1 and LJM11 Ags. Germline H- and L-chain V gene Abs generated according to mutated cross-reactive mAbs preserved their reactivity to both Ags. Our findings suggest that both Dsg1 autoantigen and LJM11 environmental Ag could be the initial antigenic stimulants for the IgG4 autoimmune responses in FS. These results support our hypothesis that LJM11 Ag plays a substantial role in triggering the IgG4 autoantibody development in FS and provide new insights on how noninfectious environmental Ag(s) may drive the generation of autoantibodies in IgG4-related autoimmune diseases.

IgG4-related Disease with Bone Marrow Involvement

A 61-year-old Japanese woman with anemia, submandibular gland swelling, and enlarged lymph nodes was diagnosed with IgG4-related disease (IgG4-RD) by lymph node biopsy. Bone marrow involvement of IgG4-RD was detected by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) and immunohistochemically proven by bone marrow biopsy in this patient. Anemia progressed gradually, and prednisolone treatment was initiated. Anemia and submandibular gland swelling improved soon after prednisolone treatment was initiated. We report a rare case of IgG4-RD involving the bone marrow. FDG-PET/CT and bone marrow biopsy were useful for diagnosis in this case.

Effectiveness of imaging modalities for screening IgG4-related dacryoadenitis and sialadenitis (Mikulicz's disease) and for differentiating it from Sjögren's syndrome (SS), with an emphasis on sonography

INTRODUCTION

The aim of this study was to clarify the effectiveness of various imaging modalities and characteristic imaging features in the screening of IgG4-related dacryoadenitis and sialadenitis (IgG4-DS), and to show the differences in the imaging features between IgG4-DS and Sjögren's syndrome (SS).

METHODS

Thirty-nine patients with IgG4-DS, 51 with SS and 36 with normal salivary glands were enrolled. Images of the parotid and submandibular glands obtained using sonography, 2-[(18)F]-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT), computed tomography (CT) and magnetic resonance imaging (MRI) were retrospectively analyzed. Six oral and maxillofacial radiologists randomly reviewed the arranged image sets under blinded conditions. Each observer scored the confidence rating regarding the presence of the characteristic imaging findings using a 5-grade rating system. After scoring various findings, diagnosis was made as normal, IgG4-DS or SS, considering all findings for each case.

RESULTS

On sonography, multiple hypoechoic areas and hyperechoic lines and/or spots in the parotid glands and obscuration of submandibular gland configuration were detected mainly in patients with SS (median scores 4, 4 and 3, respectively). Reticular and nodal patterns were observed primarily in patients with IgG4-DS (median score 5). FDG-PET/CT revealed a tendency for abnormal (18)F-FDG accumulation and swelling of both the parotid and submandibular glands in patients with IgG4-DS, particularly in the submandibular glands. On MRI, SS had a high score regarding the findings of a salt-and-pepper appearance and/or multiple cystic areas in the parotid glands (median score 4.5). Sonography showed the highest values among the four imaging modalities for sensitivity, specificity and accuracy. There were significant differences between sonography and CT (p = 0.0001) and between sonography and FDG-PET/CT (p = 0.0058) concerning accuracy.

CONCLUSIONS

Changes in the submandibular glands affected by IgG4-DS could be easily detected using sonography (characteristic bilateral nodal/reticular change) and FDG-PET/CT (abnormal (18)F-FDG accumulation). Even inexperienced observers could detect these findings. In addition, sonography could also differentiate SS. Consequently, we recommend sonography as a modality for the screening of IgG4-DS, because it is easy to use, involves no radiation exposure and is an effective imaging modality.

A case of mantle cell lymphoma presenting as IgG4-related dacryoadenitis and sialoadenitis, so-called Mikulicz's disease

Background

Mantle cell lymphoma (MCL) is a relatively uncommon type of non-Hodgkin lymphoma. It develops in the outer edge of a lymph node called the mantle zone. In contrast, IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS) is characterized by elevated serum IgG4 and persistent bilateral enlargement of lacrimal glands (LGs) and salivary glands (SGs), with infiltration of IgG4-positive plasma cells. Recent studies indicated the importance of differentiation between IgG4-DS and malignant lymphoma.

Case presentation

An 82-year-old man was suspected of IgG4-DS because of a high serum IgG level (2174 mg/dL) and bilateral swelling of LGs and SGs. Lip biopsy and fine needle biopsy of submandibular gland were performed, and subsequently, MCL was diagnosed through the histopathological findings.

Conclusions

MCL most commonly occurs in the Waldeyer ring, but rarely in the stomach, spleen, skin, LG, and SG. We report an unusual case of MCL involving LGs and SGs mimicking IgG4-DS, which suggests that IgG4 testing may be useful in the differentiation of IgG4-DS in the presence of bilateral swelling of LGs or SGs.

Epstein-Barr virus in the enlarged salivary tissues of patients with IgG4-related disease

OBJECTIVE

Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized disease entity characterized by high-serum IgG4 concentration and IgG4-producing plasma cell production with fibrotic or sclerotic changes in affected organs. We aimed to clarify the roles of Epstein-Barr virus (EBV) in patients with IgG4-RDs.

STUDY DESIGN AND SETTING

A retrospective clinical study at the Yamagata University School of Medicine, Yamagata, Japan.

METHODS

The patient group consisted of four males and four females with an average age of 62 years (range: 48-73). Expression of IgG4, latent member protein 1, EBV nuclear antigens-2, and EBV-encoded RNA in affected salivary glands from patients with IgG4-RD was examined by using immunohistochemistry and in situ hybridization. The copy number of EBV DNA in the salivary glands was also investigated by real-time polymerase chain reaction.

RESULTS

All patients had hard masses in the salivary or lacrimal glands, or both, bilaterally. Serum concentrations of IgG4 were elevated in all cases (mean 589.1, range 129-1750), and IgG4-positive plasmacytes were observed in the involved salivary glands. Four patients developed potentially life-threatening systemic involvement after initial salivary gland swelling. EBV-associated molecules (EBNA and EBER) were overexpressed in the affected salivary glands. The copy number of EBV DNA was significantly higher in patients with potentially life-threatening systemic involvement than in patients without systemic involvement (P < 0.05).

CONCLUSION

These results suggest that the copy number of EBV DNA could be useful as diagnostic findings in IgG4-RD to predict potentially life-threatening systemic involvement.

LEVEL OF EVIDENCE

4.

IgG4-Related Disease Presenting as a Solitary Neck Mass

IgG4-related disease is a newly recognized entity associated with autoimmune conditions involving almost every organ system. It is characterized by elevated serum IgG4 as well as mass like tissue infiltration by IgG4-positive plasma cells. Imaging findings are nonspecific, vary depending on the site of disease, and include mass like enlargement of the salivary or lacrimal glands and enlarged lymph nodes. Radiographic findings often mimic malignancy, necessitating tissue sampling to confirm the diagnosis. Distinguishing IgG4-related disease from malignancy is important as IgG4 responds well to steroids and conservative management.

A case of marginal zone B cell lymphoma mimicking IgG4-related dacryoadenitis and sialoadenitis

Background

IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS), so-called Mikulicz’s disease, is characterized by elevated serum IgG4 and infiltration of IgG4-positive plasma cells in glandular tissues. Recently, several studies reported both malignant lymphoma developed on the background of IgG4-associated conditions and IgG4-producing malignant lymphoma (non-IgG4-related disease).

Case presentation

We report on the case of a 70-year-old man who was strongly suspected IgG4-DS because of high serum IgG4 concentration (215 mg/dl) and bilateral swelling of parotid and submandibular glands. Biopsies of cervical lymph node and a portion of submandibular gland were performed. These histopathological findings subsequently confirmed a diagnosis of marginal zone B cell lymphoma.

Conclusion

Differential diagnosis of IgG4-DS is necessary from other disorders, including Sjögren’s syndrome, sarcoidosis, Castleman’s disease, Wegener’s granulomatosis, lymphoma, and cancer. We suggest that biopsy of swollen lesions is important for a definitive diagnosis of IgG4-DS and discuss the mechanism of development in this case.

Polyclonal hyperviscosity syndrome in IgG4-related disease and associated conditions

Polyclonal hyperviscosity syndrome (HVS) is rare and has been reported in various disorders of immune dysregulation and lymphoid hyperplasia. IgG4-Related Disease (IgG4-RD) is an emerging disorder often associated with exuberant hypergammaglobulinemia, and this review of seven cases establishes IgG4-RD as an important cause of polyclonal HVS.

Clinicopathologic features of orbital immunoglobulin G4-related disease (IgG4-RD): a case series and literature review

BACKGROUND

Involvement of orbital structures by immunoglobulin G4-related disease (IgG4-RD) is not uncommon. We conducted this study to evaluate the clinicopathologic features of orbital IgG4-RD.

MATERIAL/METHODS

This was a retrospective, clinicopathologic study. Clinical records, light microscopic features, results of immunostaining with IgG & IgG4 and laboratory findings were reviewed in 16 patients diagnosed with orbital IgG4-RD.

RESULTS

Eleven patients had a bilateral disease, and the lacrimal gland was involved in 14. Dense sclerosis, plasma cell aggregates and dense lymphoplasmacytic infiltrate were seen in all patients. Serum IgG4 titre was elevated in 12 patients. Nine patients responded completely to glucocorticoid treatment. Five patients had a relapse on discontinuation of treatment.

CONCLUSION

Orbital IgG4-RD is a distinct clinicopathologic entity requiring increased awareness and needs to be differentiated from other orbital lymphoproliferative lesions.

IgG4-related systemic disease mimicking renal pelvic cancer: a rare case

Background

Immunoglobulin G4–related disease (IgG4-RD) is a new clinical entity. Characteristic features of IgG4-RD are elevated serum IgG4 levels, infiltration of IgG4-positive cells, mass-forming lesions with fibrosis and good response to corticosteroids. The variable imaging features of IgG4-RD and the overlap with other differential diagnoses often pose a diagnostic challenge, as they frequently mimic malignant tumors or other inflammatory diseases in the abdomen.

Case presentation

A 54-year-old woman visited our hospital with left flank discomfort and palpebral edema. Computed tomography, magnetic resonance imaging, retrograde pyelography and positron emission tomography/computed tomography indicated renal pelvic cancer. However, after a left-sided nephroureteral cystectomy was performed, the mass was pathologically confirmed as an IgG4-related lesion. Her elevated serum IgG4 level and a past history of sicca complex supported the diagnosis of IgG4-RD.

Conclusions

It is critical to recognize the importance of laboratory examinations such as serum IgG4 level if a patient has a past history of rheumatic disease.

Tubulointerstitial fibrosis in patients with IgG4-related kidney disease: pathological findings on repeat renal biopsy

Renal parenchymal lesions in patients with IgG4-related kidney disease (IgG4-RKD) are characterized by tubulointerstitial nephritis with storiform fibrosis and infiltration by high numbers of IgG4-positive plasma cells. The aim of this study was to evaluate the clinical and pathological effects of corticosteroid therapy in patients with IgG4-RKD. Of six patients who were diagnosed with IgG4-RKD, four patients underwent re-biopsy at approximately 30-50 days after corticosteroid therapy was initiated. Based on the classification of Yamaguchi et al., the degree of tubulointerstitial fibrosis was classified before and after therapy. In addition, tubulointerstitial expression patterns of α-smooth muscle actin (α-SMA), collagen I, III, and IV protein, and connective tissue growth factor (CTGF) mRNA were examined. Histopathological findings before treatment showed α-SMA-positive myofibroblasts in the lesion, and CTGF mRNA-positive cells were found in the cellular infiltrate. Although corticosteroid therapy improved serum creatinine clinically, the stage of fibrosis advanced pathologically as evidenced by increased staining for collagen I and III. However, the number of IgG4-positive plasma cells decreased, and CTGF mRNA expression reduced. In other words, fibrosis had advanced from the time of extensive cell infiltration in patients with IgG4-RKD and inflammation was relieved by corticosteroid. A reduced number of positive CTGF mRNA expression cells in repeat biopsies indicated that the fibrosis process was terminated by corticosteroid therapy. We propose that corticosteroid therapy could terminate the pathway of active fibrosis, thereby inhibiting progression to renal dysfunction.