Clinicopathologic similarities between Mikulicz disease and Küttner tumor

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.

Increased Expression of Activation-Induced Cytidine Deaminase in Sinus Mucosa from IgG4-Related Disease Patients with Comorbid Chronic Rhinosinusitis

OBJECTIVE

IgG4-related disease (IgG4-RD) is a systemic condition characterized by an elevated serum IgG4 level, localized infiltration of IgG4-positive plasma cells, and lesions in various organs. IgG4-RD also shows high rates of complication with allergic diseases and is often accompanied by elevated serum IgE levels. Reports in recent years have also shown high rates of complication with chronic rhinosinusitis (CRS) and its characteristic nasal manifestations. Accordingly, we speculate that there may be a distinct form of CRS that, as an IgG4-RD, differs from other CRS. Here, we investigated whether the elevated levels of factors that are thought to be important in the pathogenesis of IgG4-RD are also seen in the sinus mucosa of IgG4-RD-associated CRS patients.

METHODS

Ethmoid sinus mucosa specimens from 9 IgG4-RD (6 Mikulicz disease and 3 Küttner's tumor) patients with elevated serum IgG4 and IgE and from 22 control CRS patients were examined immunohistochemically for Treg cytokines (IL-10 and TGF-β), activation-induced cytidine deaminase (AID), and immunocompetent cells. The 22 control CRS patients were divided into 3 subgroups based on the serological findings for IgG4 and IgE. Quantitative real-time PCR was performed to examine the expression of AID.

RESULTS

The ethmoid sinus mucosa from patients with IgG4-RD-associated CRS showed, in comparison with the 3 CRS control subgroups, significantly elevated AID production. Their mucosa also showed significantly increased infiltration of CD-20-positive immunocompetent cells compared with the controls. On the other hand, immunohistochemical examination found no significant differences in the number of IL-10- or TGF-β-positive cells.

CONCLUSION

Ethmoid sinus mucosa from IgG4-RD-associated CRS patients showed clearly increased AID production, suggesting AID involvement in class-switching to IgG4 in those local sites. This implies the existence of a distinct form of CRS that is an IgG4-RD.

The prevalence of extra-salivary gland complications in immunoglobulin G4-related sialadenitis

OBJECTIVES

To estimate the prevalence of extra-glandular lesions in patients with immunoglobulin G4-related sialadenitis (IgG4-RS).

METHODS

Six electronic databases (PubMed, EMBASE, Science Direct, Scopus, Web of Science, and China National Knowledge Infrastructure) were systematically searched from the date of inception of each database to March 2021. The Strengthening the Reporting of Observational Studies in Epidemiology statement was used to conduct methodological quality assessment, and a random-effect meta-analysis model was applied to estimate the prevalence. Publication bias was visually assessed using a funnel plot and calculated via Begg's and Egger's tests. The Stata 15 software was used to perform data analysis.

RESULTS

A total of 43 articles comprising 1,864 patients with IgG4-RS were considered to be eligible for this study. The pooled prevalence of extra-salivary gland lesions in IgG4-RS was 76.53% with a confidence interval (CI) of (69.39%, 83.04%). A higher prevalence was associated with studies published before or during 2015 (84.38%, CI [74.23%, 92.58%]) than those published after 2015 (68.55%, CI [58.44%, 77.88%]). Lacrimal gland involvement (54.68%, CI [45.61%, 63.60%]) and lymph node swelling (56.96%, CI [48.16%, 65.56%]) were the most frequent lesions.

CONCLUSIONS

Extra-glandular lesions were common in patients with IgG4-RS. More high-quality prospective studies with less heterogeneity are required to determine the accurate prevalence.

Localized IgG4-related disease manifested on the tongue: a case report

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition that can affect multiple organs. IgG4-RD may show a variety of initial symptoms. In the oral mucosa, lesions present as inflammatory fibrosis with a large number of IgG4-positive plasma cells. Evaluating treatment is a well-known problem in IgG4-RD due to the absence of an established assessment system. There are difficulties in defining the severity of the disease, which is why treatment is primarily based on its clinical manifestations. We present a case report of localized IgG4-RD with ulcerative and proliferative manifestations on the tongue, which clinically mimicked oral squamous cell carcinoma. A tumor-like lesion on the tongue can indicate something else other than the malignant or reactive changes commonly found in the oral mucosa. Multiple differential diagnoses of these atypical oral lesions, including localized IgG4-RD, should be considered.

Mikulicz's disease and Küttner's tumor as manifestations of IgG4-related diseases: a review of the literature

According to a new concept for the classification and division of autoimmune diseases, Mikulicz's disease and Küttner's tumor belong to immunoglobulin G4-related diseases (IgG4-RD) and fulfil their diagnostic criteria. The aim of this study was to summarize the new classification concepts of IgG4-RD in the head and neck area and to review their clinical, histopathological and serologic criteria and the methods used in the diagnostic workup with respect to their advantages, limitations and differentiative value. The PubMed, Web of Science, Google Scholar, and Scopus databases were searched for articles published between 2009 and 2019 using the following key words: IgG4-related diseases, Mikulicz's disease, Küttner's tumor, salivary glands, xerostomia. Results of the review of the literature revealed that Mikulicz's disease and Küttner's tumor fulfil the same diagnostic criteria but may manifest different clinical symptoms which determine the choice of the different diagnostic tools.

IgG4-rich reactive lymphoid hyperplasia of the lacrimal gland

We describe an otherwise healthy 24-year-old woman with reactive lymphoid hyperplasia of one lacrimal gland. She was found to have modest elevation of serum IgG4 and high density of IgG4+ plasma cells in her lacrimal gland, ranging from 40% to 60% of IgG+ plasma cells. The patient transiently responded to systemic corticosteroids before treatment with rituximab. IgG4-rich reactive lymphoid hyperplasia of the lacrimal gland is neither an established part of IgG4-related disease spectrum nor a known precursor lesion to lymphoma. Although there is a plausible risk of transforming to IgG4-related disease or to lymphoma, the biological potential and natural history of IgG4-rich reactive lymphoid hyperplasia remains to be determined.

Ultrasonographic and elastographic biometry in adult major salivary glands: a preliminary case-control report

Specifications about the size and stiffness of healthy salivary glands with ultrasound (US) are not available for Asian people. Using a Toshiba Apolio 500 US platform, we determined the size (including anterior-posterior median length, median paramandibular depth dimension, and cranio-caudal height) and hardness of 100 healthy submandibular and parotid glands in volunteers without a history of disease affecting the salivary glands or post-radiation, and compared the dimensions to those of 36 parotid glands and 37 submandibular glands in post-irradiated patients. The dimensions of the parotid and submandibular glands were significantly correlated with body weight. However, the dimension of the parotid glands was not significantly correlated with that of patients with prior radiation; the shear wave velocity (SWV) significantly increased (1.99 m/s versus 2.43 m/s, p-value < 0.01). The dimension of the submandibular glands was significantly correlated with prior radiation, where the SWV also significantly increased (2.32 m/s versus 2.50 m/s, p-values < 0.01). We find that US is a useful tool for assessment of the reference dimensions and hardness of major salivary glands that may be altered by irradiation.

MR Imaging of Autoimmune Pancreatitis

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

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.

Recent advances in knowledge regarding the head and neck manifestations of IgG4-related disease

IgG4-related disease (IgG4-RD) is a chronic inflammatory disorder, characterized by elevated serum IgG4 levels as well as abundant infiltration of IgG4-positive plasmacytes and fibrosis in various organs, including the head and neck region. In particular, the salivary glands, orbit, and thyroid are common sites of disease involvement. IgG4-RD is diagnosed based on various clinical, serological, and histopathological findings, none of which are pathognomonic. Hence, various differential diagnoses, which exhibit elevated serum IgG4 levels and infiltration of IgG4-postive cells into tissues, need to be excluded, especially malignant diseases and mimicking disorders. Systemic corticosteroids are generally effective in inducing IgG4-RD remission; however, recurrent or refractory cases are common. In addition, although the pathogenic mechanisms of IgG4-RD remain unclear, an antigen-driven inflammatory condition is believed to be involved. Recent studies have indicated the important pathogenic role of B cell/T cell collaboration and innate immunity in this disease. Nevertheless, additional research and discussions are needed to resolve many remaining questions. In this review, we provide an overview of the recent insights on the history, clinical features, diagnosis, and treatment of IgG4-RD in the head and neck region. Furthermore, we have also addressed the pathogenesis of this disease.

Five Top Stories in Thyroid Pathology

CONTEXT

Thyroid carcinoma is the most common malignant tumor of endocrine organs, yet it only accounts for approximately 1% of all cancers in the United States with more than 35,000 new cases diagnosed each year and more than 450,000 people living with this disease. While most tumors can be diagnosed without much difficulty, a few tumor types, especially tumors with follicular pattern, sometimes pose a diagnostic challenge.

OBJECTIVE

To discuss morphologic, immunohistochemical, and molecular features of thyroid tumors. We also explore the clinicopathologic features of papillary microcarcinoma and medullary microcarcinoma and how the latter is related and differentiated from C-cell hyperplasia. Finally with the ever-growing list of organ systems involved in immunoglobulin (Ig) G4-related diseases, we discuss the still not completely explored IgG-4-related thyroid disease.

DATA SOURCES

Data were obtained from review of the pertinent peer-reviewed literature and institutional experience.

CONCLUSIONS

Histomorphologic evaluation still remains the gold standard for diagnosis in most cases of thyroid diseases. The application of ancillary studies such as immunohistochemistry and molecular diagnosis, including next-generation sequencing, is becoming more common.

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.

Immunoglobulin G4 related chronic sclerosing sialadenitis

Background:

ENT surgeons may be the first specialists to encounter and diagnose patients with salivary gland disease. A new entity involving the salivary glands has recently been described of which ENT surgeons need to be aware: immunoglobulin G4 related chronic sclerosing sialadenitis.

Method:

A literature search of Medline, Embase and Cochrane Library databases was performed, using the search terms ‘IgG4’, ‘hyperIgG4 syndrome’ and ‘IgG4 related chronic sclerosing sialadenitis’.

Results:

Knowledge concerning immunoglobulin G4 related chronic sclerosing sialadenitis is rapidly increasing. This new entity is part of a fibro-inflammatory corticosteroid-responsive systemic disease (immunoglobulin G4 related disease) and has been described in almost every organ. Biopsy of the submandibular gland can be diagnostic. However, the diagnosis can easily be overlooked if: clinical suspicion is not high, one is unaware of the classical morphology and/or immunoglobulin G4 staining is not performed. This paper presents a summary of the current understanding of the disease and its management.

Conclusion:

ENT surgeons should be aware of this new disease entity. Patients with systemic disease should be managed under a multidisciplinary team, with input from clinicians who have an interest in such diseases (such as gastroenterologists and rheumatologists), and input from histopathologists and radiologists.

Clinical relevance of Küttner tumour and IgG4-related dacryoadenitis and sialoadenitis

Objectives

Küttner tumour (KT), so-called chronic sclerosing sialoadenitis, is characterised by concomitant swelling of the submandibular glands secondary to strong lymphocytic infiltration and fibrosis independent of sialolith formation. However, recent studies have indicated that some patients with KT develop high serum levels of IgG4 and infiltration of IgG4-positive plasma cells, namely IgG4-related dacryoadenitis and sialoadenitis (IgG4-DS), so-called Mikulicz's disease. The aim of this study was to clarify the clinical and pathological associations between KT and IgG4-DS.

Materials and Methods

Fifty-four patients pathologically diagnosed with KT or chronic sialoadenitis were divided into two groups according to the presence or absence of sialolith (KT-S (+) or KT-S (−), respectively).

Results

There were no significant differences in the clinical findings, including the mean age, sex and disease duration, between the two groups. All patients in the KT-S (+) group showed unilateral swelling without infiltration of IgG4-positive plasma cells or a history of other IgG4-related diseases (IgG4-RD), while those in the KT-S (−) group showed bilateral swelling (37.5%), strong infiltration of IgG4-positive plasma cells (87.5%) and a history of other IgG4-RD (12.5%).

Conclusions

These results suggest an association between the pathogeneses of KT-S (−) and IgG4-DS, but not KT-S (+).

The clinical characteristics of patients with IgG4-related disease with infiltration of the labial salivary gland by IgG4-positive cells

OBJECTIVES

Mikulicz's disease (MD) is an immunoglobulin (Ig) G4-related disease with systemic symptoms. Submandibular gland (SMG) biopsy is recommended for patients with possible IgG4-related MD for accurate differential diagnosis; however, it is difficult for certain patients to undergo this procedure. In contrast, labial salivary gland (LSG) biopsy is more convenient. Here we present an analysis of patients with IgG4-related MD whose LSG specimens were infiltrated with abundant IgG4-positive plasma cells.

METHODS

Sixteen patients diagnosed with IgG4-related MD underwent simultaneous SMG and LSG biopsies. We evaluated patients' serological and (18)F-fluoro-2-deoxyglucose-positron emission tomography/computed tomography ((18)F-FDG-PET/CT) and grouped them as LSG+ (LSG specimens with > 40% IgG4-positive plasma cells/IgG-positive plasma cells, 11 patients) or LSG- (LSG specimens with < 40% IgG4-positive plasma cells/IgG-positive plasma cells, 6 patients).

RESULTS

There were not significant differences in serum IgG and IgG4 levels between the two groups; however, serum concentrations of soluble interleuikin-2 receptor (sIL-2R) were significantly higher in the LSG+ group. All patients with increased (18)F-FDG uptake in their parotid glands were a part of the LSG+ group.

CONCLUSIONS

When a SMG biopsy is not possible, the serum concentration of sIL-2R and (18)F-FDG-PET/CT findings may predict whether LSG biopsy will facilitate the diagnosis of IgG4-related MD.

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.

IgG4-related autoimmune pancreatitis overlapping with Mikulicz’s disease and lymphadenitis: A case report

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that is categorized as type 1 or type 2 according to the clinical profile. Type 1 AIP, which predominantly presents in a few Asian countries, is a hyper-IgG4-related disease. We report a case of IgG4-related AIP overlapping with Mikulicz’s disease and lymphadenitis, which is rare and seldom reported in literature. A 63-year male from Northeast China was admitted for abdominal distension lasting for one year. He presented symmetric swelling of the parotid and submandibular glands with slight dysfunction of salivary secretion for 6 mo. He had a 2-year history of bilateral submandibular lymphadenopathy without pain. He underwent surgical excision of the right submandibular lymph node one year prior to admission. He denied any history of alcohol, tobacco, or illicit drug use. Serological examination revealed high fasting blood sugar level (8.8 mmol/L) and high level of IgG4 (15.2 g/L). Anti-SSA or anti-SSB were negative. Computed tomography of the abdomen showed a diffusely enlarged pancreas with loss of lobulation. Immunohistochemical stain for IgG4 demonstrated diffuse infiltration of IgG4-positive plasma cells in labial salivary gland and lymph node biopsy specimens. The patient received a dose of 30 mg/d of prednisone for three weeks. At this three-week follow-up, the patient reported no discomfort and his swollen salivary glands, neck lymph node and pancreas had returned to normal size. The patient received a maintenance dose of 10 mg/d of prednisone for 6 mo, after which his illness had not recurred.

[Interdisciplinary approach in a patient with IgG4-associated Mikulicz's disease]

The clinical picture of enlarged submandibular gland and/or enlarged lacrimal gland often leads to difficulties in differential diagnostics. From the perspective of rheumatology Sjögren's syndrome should be excluded especially in patients who complained of xerophthalmia and xerostomia for longer than 3 months. In this article the authors report the case of a patient who presented to clarify swelling of the submandibular gland and xerostomia. In close cooperation with rheumatologists, otolaryngologists and pathologists the diagnosis of IgG4-associated sialoadenitis (IgG4-associated Mikulicz's disease) could be reached.

IgG4-related disease of the head and neck

IgG4-related disease is an uncommon sclerosing and inflammatory mass-forming disease that may affect a single organ or be systemic. The prototypical example of the disease is type 1 autoimmune pancreatitis. After the pancreatobiliary system, the head and neck is the next most common site for involvement by IgG4-related disease. Here, we describe the clinicopathologic features of the head and neck involvement by this disease process with particular attention to involvement of the major salivary glands, the lacrimal glands and periorbital tissues, the upper aerodigestive tract, the thyroid gland, lymph nodes, the ear, and the skin and soft tissues.

IgG4-related disease in the head and neck

Lymphoid infiltrates are relatively common in the ocular adnexa and the salivary glands. They are of a variety of types and include both reactive processes and lymphomas. Within the ocular adnexa in years past, lymphoid proliferations were classified as inflammatory pseudotumor, reactive lymphoid hyperplasia, atypical lymphoid hyperplasia, and lymphoma. With improvements in diagnostic techniques and with advances in lymphoma subclassification, it became clear that many of the dense lymphoid infiltrates, including cases classified as lymphoma and likely some classified as atypical lymphoid hyperplasia, represented low-grade B-cell lymphomas, the most common of which by far were extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT) lymphomas. Ocular adnexal inflammatory pseudotumor, reactive lymphoid hyperplasia, and chronic sclerosing sialadenitis were recognized, but the focus in diagnosis had been on avoiding misdiagnosis as a neoplastic process and in planning appropriate therapy. Recently, it has become clear that many cases of these reactive processes fall into the spectrum of immunoglobulin G4 (IgG4)-related disease, offering new insight into the pathogenesis of inflammatory lesions occurring in the ocular adnexa and the salivary glands. The majority of entities previously classified as chronic sclerosing sialadenitis, Mikulicz disease, orbital pseudolymphoma, and eosinophilic angiocentric fibrosis are now considered a part of the IgG4-related disease spectrum. In this review, we discuss the histologic and immunohistochemical features of IgG4-related disease of the head and neck and provide guidance for distinguishing this disease from its many mimics.

A case of multiple giant coronary aneurysms and abdominal aortic aneurysm coexisting with IgG4-related disease

IgG4-related disease (IgG4RD) is a unique systemic lymphoproliferative disorder characterized by elevated serum IgG4 levels and IgG4-producing plasma cell expansion in the affected tissues, which are accompanied by fibrotic or sclerotic changes. Vascular lesions may also be a part of IgG4RD as a number of case reports have discussed inflammatory abdominal aortic aneurysms associated with IgG4RD, but coronary artery lesions seem to be rare complications of IgG4RD. A 71-year-old man suffered from multiple giant coronary aneurysms and an abdominal aortic aneurysm with concurrent pancreatic, gall bladder, bile duct, and salivary gland lesions resulting from IgG4RD. The present observations suggest that coronary aneurysms may also develop as a consequence of this disease.

Utility of FDG PET/CT in IgG4-related systemic disease

IgG4-related systemic disease (IgG4-RSD) is an emerging clinical entity about which much remains to be elucidated, in terms of its aetiology, pathogenesis, diagnosis, treatment and outcome. Autoimmune pancreatitis (AIP) and Mikulicz disease (MD) are the two major, well-studied constituents of IgG4-RSD. AIP and MD have common characteristics of forming tumour-mimicking lesions that consist of lymphoplasmacytic infiltrates and fibrosclerosis with numerous immunoglobulin G4 (IgG4)-positive plasma cells, as well as various multi-organ manifestations of IgG4-RSD. 2-[(18)F]-fluoro-2-deoxy-d-glucose positron-emission tomography/ computed tomography (FDG PET/CT) enables the acquisition of whole-body images and provides functional information about disease activity; as such it has a valuable role in staging extent of disease, guiding biopsy, and monitoring response to treatment. However, FDG PET/CT is likely to be only one component of the management strategy, and clinical, laboratory, imaging and histological findings are crucial in the overall diagnosis of the condition. At present FDG PET/CT does not have a well-established role in the assessment of patients with IgG4-RSD and future prospective studies are required to define the cost-effectiveness and clinical impact in this patient group more accurately.

A novel concept of Mikulicz's disease as IgG4-related disease

Since Morgan's report in 1953, Mikulicz's disease (MD) has been considered part of primary Sjögren's syndrome (SS). However, MD has a unique presentation, including persistent swelling of the lacrimal and salivary glands, and is characterized by good responsiveness to glucocorticoids, leading to recovery of gland function. Recently, it has been revealed that MD patients show elevated serum immunoglobulin G4 (IgG4) levels and prominent infiltration of IgG4-positive plasmacytes. The complications of MD include autoimmune pancreatitis, retroperitoneal fibrosis, tubulointerstitial nephritis, autoimmune hypophysitis, and Riedel's thyroiditis, all of which show IgG4 involvement in their pathogenesis. Thus, MD is a systemic "IgG4-related disease." In addition, recent analyses have revealed that Küttner's tumor (KT), a chronic sclerosing sialadenitis that presents with asymmetrical firm swelling of the submandibular glands, is also associated with prominent infiltration of IgG4-positive plasmacytes. MD and KT differ from SS and are thought to be singular systemic IgG4-related plasmacytic diseases. Here we discuss the results of recent studies and provide an overview of MD as an IgG4-related disease.

A clinical study of olfactory dysfunction in patients with Mikulicz's disease

OBJECTIVE

Mikulicz's disease (MD) is differentiated from Sjögren's syndrome as an immunoglobulin G4 (IgG4) systemic disease. MD patients often report olfactory dysfunction (OD). To analyze cases of OD associated with MD, we studied clinicopathological and serological findings of MD patients.

METHODS

A total of 44 MD patients (17 males and 27 females) were examined for OD. We evaluated clinicopathological and serological findings of these patients by dividing them into OD(+) and OD(-) groups.

RESULTS

The mean IgG4 concentration (SD) in such cases was 950.5 (797.5)mg/dl. Of the 44 patients, 20 (45%) had OD even though no abnormalities, such as obstructive and inflammatory disease, were detected in their nasal cavities and sinuses. The two groups did not show significant differences in background characteristics, such as age, sex, IgG4 concentration, presence or absence of allergic rhinitis, and presence or absence of extrasalivary gland lesions. We found abundant IgG4-positive plasmacytes in the nasal mucosa specimens of the OD(+) group but not in that of the OD(-) group.

CONCLUSIONS

Nasal mucosa in the MD patients with OD was infiltrated with IgG4-positive plasmacytes. We concluded that OD may be associated with infiltration by IgG4-positive cells.