Riedel's thyroiditis and multifocal fibrosclerosis are part of the IgG4-related systemic disease spectrum

Clinicopathological characteristics of immunoglobulin G4-related sialadenitis

Introduction

Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized fibro-inflammatory condition. Forty-two cases with immunoglobulin G4-related sialadenitis (IgG4-RS) confirmed by histopathological and immunohistochemical assessment were studied to clarify the clinicopathologic characteristics of the salivary glands involved in IgG4-RS, especially the relationship between the histopathologic features and function of salivary glands or serum levels of IgG4.

Methods

Clinical, serologic, imaging and histopathological data of these cases were analyzed. CT volumes of submandibular, parotid, and lacrimal glands were calculated. The saliva flow rate was measured. Scintigraphy with 99mTc-pertechnetate was undertaken in 31 cases, and the concentration index (CI) and secretion index (SI) was calculated. Relationships between fibrosis severity and salivary gland function or serum IgG4 levels were analyzed.

Results

The first symptom was swelling of bilateral submandibular or lacrimal glands. Physical examination showed multiple bilateral major salivary glands (including sublingual and accessory parotid glands) and lacrimal glands were enlarged in IgG4 RS. Multiple enlarged cervical lymph nodes were noted in 30 patients. Saliva flow at rest was lower than normal in 34 cases; stimulated saliva flow was lower than normal in 15 cases. Secretory function was reduced more severely in the submandibular glands than in the parotid glands. Serum levels of IgG4 were elevated in 95.2% of cases and 78.6% patients had increased IgE levels. Serum IgG4 level was higher and saliva secretion lower as glandular fibrosis increased.

Conclusions

Prominent changes in the morphology, histology, immunohistochemistry and secretion of the major salivary glands of IgG4-RS patients were accompanied by involvement of the lacrimal glands and cervical lymph nodes. Elevated IgE, allergic history, eosinophil infiltration suggest allergic reactions as a potential pathogenesis of IgG4-RS. Severity of glandular fibrosis correlated with salivary function and serum levels of IgG4.

Immunoglobulin G4-related diseases in the head and neck: a systematic review

BACKGROUND

Immunoglobulin G4 related disease (IgG4-RD) is a poorly understood chronic inflammatory disorder affecting the middle-aged and elderly that can present to the otolaryngologist. We aim to summarize the current literature regarding the manifestations and management of IgG4-RD in the head and neck.

METHODS

Pubmed and EMBASE were searched using the term relevant search algorithm utilizing keywords such as: IgG4 related disease, head and neck, orbit, salivary glands, sialadenitis, Kuttner, angiocentric eosinophilic fibrosis, submandibular, lacrimal, thyroid, dacryoadenitis, nasal, sinus, and Mikulicz's. Reference lists were searched for identification of relevant studies. Case reports, original research and review articles published in English from 1964 to 2014 whose major topic was IgG4-RD affecting the head and neck were included. Data regarding patient demographics, presentation, histopathology, management and treatment outcomes of IgG4-RD were extracted. Level of evidence was also assessed and data were pooled where possible. Three independent reviewers screened eligible studies; extracted relevant data and discrepancies were resolved by consensus, where applicable. Descriptive and comparative statistics were performed.

RESULTS

Fourty-three articles met our inclusion criteria. IgG4-RD most often presents as a mass lesion in the head and neck region. Common diagnostic features include: (1) elevated serum IgG4 level, (2) marked infiltration of exocrine glands by IgG4-positive plasma cells with fibrosis, and (3) marked improvement with corticosteroid therapy and additional immunosuppressive therapy in corticosteroid refractory cases. Early diagnosis and involvement of rheumatology is important in management.

CONCLUSIONS

IgG4-RD is a challenging non-surgical disease that has multiple manifestations in the head and neck. It must be distinguished from various mimics including malignancy, systemic diseases, and infectious. Otolaryngology-Head and Neck surgeons should be aware of this condition and its management.

IgG4-Related Disease Combined with Autoimmune Hemolytic Anemia and Steroid-Responsive Transient Hypercalcemia

A 67-year-old man with elevated serum immunoglobulin G4 (IgG4) levels, systemic lymphadenopathy infiltrated by IgG4-positive plasma cells, and Coombs-positive autoimmune hemolytic anemia (AIHA) showed marked hypercalcemia. Although the intact parathyroid hormone (PTH) level was elevated, 99mTc-MIBI scintigraphy and thyroid ultrasonography revealed no evidence of primary hyperparathyroidism. Liver biopsy showed marked infiltration of IgG4-positive plasma cells, which confirmed the diagnosis of IgG4-related disease (IgG4-RD). Corticosteroid therapy was initiated, and subsequently, intact PTH and serum calcium levels gradually normalized. Transient hypercalcemia in a patient with AIHA may therefore be associated with IgG4-RD.

Immunology of IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition that derives its name from the characteristic finding of abundant IgG4(+) plasma cells in affected tissues, as well as the presence of elevated serum IgG4 concentrations in many patients. In contrast to fibrotic disorders, such as systemic sclerosis or idiopathic pulmonary fibrosis in which the tissues fibrosis has remained largely intractable to treatment, many IgG4-RD patients appear to have a condition in which the collagen deposition is reversible. The mechanisms underlying this peculiar feature remain unknown, but the remarkable efficacy of B cell depletion in these patients supports an important pathogenic role of B cell/T cell collaboration. In particular, aberrant T helper type 2 (Th2)/regulatory T cells sustained by putative autoreactive B cells have been proposed to drive collagen deposition through the production of profibrotic cytokines, but definitive demonstrations of this hypothesis are lacking. Indeed, a number of unsolved questions need to be addressed in order to fully understand the pathogenesis of IgG4-RD. These include the identification of an antigenic trigger(s), the implications (if any) of IgG4 antibodies for pathophysiology and the precise immunological mechanisms leading to fibrosis. Recent investigations have also raised the possibility that innate immunity might precede adaptive immunity, thus further complicating the pathological scenario. Here, we aim to review the most recent insights on the immunology of IgG4-RD, focusing on the relative contribution of innate and adaptive immune responses to the full pathological phenotype of this fibrotic condition. Clinical, histological and therapeutic features are also addressed.

A mass in the junction of the body and tail of the pancreas with negative IgG4 serology: IgG4-related disease with negative serology

Patient:Female, 55

Final Diagnosis: Autoimmune pancreatitis

Symptoms: Abdominal pain • weight loss

Medication: Prednisone

Clinical Procedure: Admitted to the hospital

Specialty: Gastroenterology and Hepatology

Overlapping Morphologic and Immunohistochemical Features of Hashimoto Thyroiditis and IgG4-Related Thyroid Disease

Immunoglobulin G4-related disease (IgG4-RD) is an emerging clinicopathologic entity characterized by both IgG4+ plasma cell infiltration and fibrosis in one or more organs, prototypically pancreas or salivary/lacrimal glands. IgG4-RD in the thyroid (IgG4-RTD) is an area of active study, and the relationship between IgG4-RTD and Hashimoto thyroiditis is not fully delineated due to their overlapping histologic features. Retrospective review was performed of all thyroidectomy cases demonstrating lymphocytic inflammation at a single institution over a 4-year period. Approximately half (23/38) of patients had a clinical diagnosis of Hashimoto thyroiditis (HT). Nine of the 38 patients had increased absolute and relative numbers of IgG4+ plasma cells. Patients with a clinical diagnosis of HT had increased lymphoplasmacytic inflammation, but the relative proportion of IgG4+ plasma cells was not increased compared to patients without HT. There was no correlation between IgG4 levels and the amount of fibrosis in patients with or without HT. Patients identified as having the fibrosing variant of HT were not more likely to have increased levels of IgG4+ plasma cells than those without. There is significant morphologic and immunohistochemical overlap between HT and IgG4-RTD. Future studies to identify specific characteristics of IgG4-RTD involving the thyroid are necessary to accurately define this entity.

IgG4-related disease

IgG4-related disease is a protean condition that mimics many malignant, infectious, and inflammatory disorders. This multi-organ immune-mediated condition links many disorders previously regarded as isolated, single-organ diseases without any known underlying systemic condition. It was recognised as a unified entity only 10 years ago. Histopathology is the key to diagnosis. The three central pathology features of IgG4-related disease are lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis. The extent of fibrosis is an important determinant of responsiveness to immunosuppressive therapies. IgG4-related disease generally responds to glucocorticoids in its inflammatory stage, but recurrent or refractory cases are common. Important mechanistic insights have been derived from studies of patients treated by B-cell depletion. Greater awareness of this disease is needed to ensure earlier diagnoses, which can prevent severe organ damage, disabling tissue fibrosis, and even death. Identification of specific antigens and T-cell clones that drive the disease will be the first steps to elucidate the pathogenesis of IgG4-related disease.

Cerebral involvement in IgG4-related disease

IgG4-related disease is a recently recognised multi-system disease. Common organ involvement includes the pancreas, biliary tree and salivary glands. Central nervous system involvement has been infrequently reported. In a single-centre cohort of 84 patients, we report cerebral involvement in three (4%) patients. Details of cerebral involvement in these patients are outlined, including pituitary involvement in two patients and a diffuse autoimmune-like encephalopathy in the other.

IgG4 related disease of the head and neck

IgG4 related disease of the head and neck region represents one of the more common manifestations of IgG4 related disease. Involvement of the submandibular and parotid glands, the orbit and thyroid represent some of the more common sites involved by IgG4 related disease. Eosinophilic angiocentric fibrosis, Mikulicz disease and Riedel thyroiditis are also members of the family of IgG4 related disease. Clinically, the disease is characterized by tumefactive lesions, often multicentric, that show a swift response to immunosuppressive therapy. An elevated serum IgG4 represents the only validated blood based biomarker. However, elevated serum IgG4 is detected in only half the patients with this disease. Histology continues to represent the gold standard for the diagnosis of IgG4 related disease: storiform-type fibrosis and obliterative phlebitis constitute characteristic features of this disease. A definitive diagnosis of IgG4 related disease also requires the presence of elevated numbers of IgG4 positive plasma cells as well as an IgG4 to IgG ratio of greater than 40 %. In isolation, elevated numbers of IgG4 positive plasma cells represents a non-specific feature, detected in a variety of other inflammatory as well as neoplastic diseases. Attention to the clinical context, histological features, as well as an elevated IgG4 to IgG ratio is critical to avoiding overdiagnosis of IgG4 related disease.

Clinicopathological features of Riedel's thyroiditis associated with IgG4-related disease in Japan

Riedel's thyroiditis (RT) is a rare chronic fibrosing disorder characterized by a hard, infiltrative lesion in the thyroid gland, which is often associated with multifocal fibrosclerosis. Immunoglobulin G4-related disease (IgG4-RD) is typified by infiltration of IgG4-positive plasma cells into multiple organs, resulting in tissue fibrosis and organ dysfunction. In order to evaluate the clinicopathological features of RT and its relationship with IgG4-RD, we performed a Japanese literature search using the keywords "Riedel" and "Riedel's thyroiditis." We used the electronic databases Medline and Igaku Chuo Zasshi, the latter of which is the largest medical literature database in Japan. The diagnosis of RT was based on the presence of a fibroinflammatory process with extension into surrounding tissues. Only 10 patients in Japan fulfilled RT diagnostic criteria during the 25-year period between 1988 and 2012. Two patients with confirmed IgG4/IgG immunohistochemical findings demonstrated 43 and 13 IgG4-positive plasma cells per high-power field, respectively, and the IgG4-positive/IgG-positive plasma cell ratios of 20% and less than 5%. Of the 10 patients with RT, two received glucocorticoids, one of whom experienced marked shrinkage of the thyroid lesion. One patient had extra-thyroid involvement in the form of retroperitoneal fibrosis. Although the clinicopathological features of RT suggest that IgG4-RD may be the underlying condition in some cases, further investigation is needed to clarify the etiology of RT in relation to IgG4-RD.

Multifocal Fibrosclerosis with Hypertrophic Pachymeningitis and a Soft Tissue Mass around the Thoracic Vertebral Bodies: A Case Report with Review of the Literature

Multifocal fibrosclerosis is the term used to represent a combination of similar fibrous lesions occurring at different anatomical sites. We herein report a hypertrophic pachymeningitis patient with a soft tissue mass around the thoracic vertebral bodies. A histopathological analysis of the biopsied tissues from both lesions showed dense fibrosis and a marked infiltration of lymphocytes and plasma cells, which lead to the diagnosis of multifocal fibrosclerosis. This pathological condition closely resembles that of IgG4-related disease and is a very rare combination of manifestations. Our case suggests that hypertrophic pachymeningitis patients need to also undergo a whole body examination.

Distribution of serum immunoglobulin G4 levels in Hashimoto's thyroiditis and clinical features of Hashimoto's thyroiditis with elevated serum immunoglobulin G4 levels

Immunoglobulin G4-related disease (IgG4-RD) is characterized by elevated serum IgG4 levels, IgG4-positive plasmacytes, and lymphocyte infiltration into multiple organs. IgG4 thyroiditis is a subset of patients with Hashimoto's thyroiditis (HT) who exhibited histopathological features of IgG4-RD; its source of serum IgG4 is suggested to be the thyroid gland. Although a relationship between IgG4-RD and IgG4 thyroiditis has been reported, the meaning of serum IgG4 in HT is uncertain. In this report, we prospectively evaluated serum IgG4 levels and clinical features of patients with HT. A total of 149 patients with HT were prospectively recruited into this study. According to the comprehensive diagnostic criteria of IgG4-RD, patients were divided into two groups: elevated IgG4 (>135 mg/dL) and non-elevated IgG4 (≤135 mg/dL). Median serum IgG4 levels of HT patients were 32.0 mg/dL (interquartile range, 20.0-65.0), with a unimodal non-normal distribution. Six patients (4.0%) had elevated serum IgG4 levels above 135 mg/dL. The elevated IgG4 group was older and exhibited enlarged hypoechoic areas in the thyroid gland, as revealed by ultrasonography, relative to the non-elevated IgG4 group. Levothyroxine (L-T4) replacement doses and titers of anti-thyroid antibodies did not differ significantly between the two groups. Two out of six HT patients with elevated serum IgG4 levels had extra-thyroid organ involvement as seen in IgG4-RD. In conclusion, HT patients with elevated serum IgG4 levels shared clinical features with both IgG4-RD and IgG4 thyroiditis. Longer follow-up periods and histopathological assessments are needed to further understand the meaning of elevated serum IgG4 levels in HT.

IgG4-Related Disease: A Multispecialty Condition

IgG4-related disease (IgG4-RD) is a recently recognized group of conditions, characterized by tumor-like swelling of involved organs, lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells, variable degrees of fibrosis, and elevated serum IgG4 concentrations. Currently IgG4-RD is recognized as a systemic condition that can affect several organs and tissues. Herein we report the case of a 34-year-old male patient who was admitted to our hospital with diffuse abdominal pain, weight loss, and painful stiffness in his neck. He had a history of tumoral mass of the left maxillary region, right palpebral ptosis with protrusion of the eyeball, and chronic dry cough for about 6 years. Laboratory tests revealed polyclonal hypergammaglobulinemia and increased serum IgG4 levels. Immunohistochemical staining of the maxillary biopsy was compatible with IgG4-RD. He had an excellent response to corticosteroid therapy. This case highlights that IgG4-RD should be included in the differential diagnosis with multisystem diseases.

IgG4 related renal disease: A wolf in sheep's clothing

IgG4 related disease is a fibro-inflammatory condition with involvement of renal and extra renal organs, characterized by lymphoplasmacytic infiltration with organ dysfunction. We describe three cases of IgG4 related renal disease from a tertiary care hospital in south India.

Riedel's Thyroiditis in an Elderly Male Patient: A Rare Entity

Riedel's thyroiditis (RT) is a rare fibrosclerotic infiltrative thyroid disorder of unclear aetiology. It has been reported in 0.06% of thyroid surgeries and is more common in women. A 60-year-old euthyroid male presented with thyroid swelling and sinus discharge since three years, associated with pain and fever. Near total thyroidectomy revealed right lobe measuring 5x2.5x2 cm, well encapsulated, firm to hard with resistance on cutting. Microscopic examination showed variable sized colloid filled follicles with intervening areas of dense fibrosis admixed with lymphocytic aggregates and perivascular fibrosis extending to the thyroid capsule. The diagnosis of Riedel's thyroiditis was made on histopathological examination. Hence, we would like to emphasize that Riedel's thyroiditis requires diagnostic thyroidectomy and histopathological examination for confirmation.

Biliary and hepatic involvement in IgG4-related disease

BACKGROUND

IgG4-related disease (IgG4-RD) is a multi-systemic disorder. IgG4-related sclerosing cholangitis (IgG4-SC) is the biliary manifestation of the disease, often in association with autoimmune pancreatitis (AIP). Hepatic manifestations of IgG4-RD are less well described within the literature.

AIM

To examine and present an overview of IgG4-RD with a focus on the biliary and hepatic manifestations.

METHODS

An electronic search using Medline was performed. Search items included 'IgG4 multi-system disease, IgG4 associated cholangitis, IgG4 associated liver disease and autoimmune pancreatitis (AIP)'.

RESULTS

IgG4-RD is characterised by an IgG4-positive lymphoplasmacytic tissue infiltrate, storiform fibrosis and an obliterative phlebitis. The HISORt criteria may be used to establish the diagnosis and incorporate a multi-disciplinary approach involving histology, radiology, serum IgG4 levels and response to steroid therapy. IgG4-SC is the commonest extrapancreatic manifestation of type-1 AIP, while the hepatic manifestations remain poorly defined. Important differential diagnoses include primary sclerosing cholangitis, secondary sclerosing cholangitis, cholangiocarcinoma and pancreatic carcinoma. Current treatment regimens remain ill defined although steroid therapy is used first line unless contraindicated. Patients with relapsing disease or multifocal disease should be considered for azathioprine. Available data would also suggest a role for rituximab.

CONCLUSIONS

IgG4-related sclerosing cholangitis is a common manifestation of IgG4-related disease which requires a multi-disciplinary approach to establish the diagnosis. Differentiating IgG4-related sclerosing cholangitis from other conditions, both benign and malignant, is challenging, but vital. Steroids remain the mainstay of treatment. Our understanding of the pathogenesis of the hepatic manifestations of IgG4-related disease continues to evolve.

Fibrosis of the thyroid gland caused by an IgG4-related sclerosing disease: three years of follow-up

Immunoglobulin G4-related sclerosing disease (IgG4-RSD) represents a recently identified inflammatory disorder in which infiltration of IgG4 plasma cells causes fibrosis in organs. While IgG4-RSD is well documented in the pancreas and other organs, it is poorly characterized in the thyroid gland. We report a case of a 48-year-old female with a fibrotic thyroid mass associated with a retroperitoneal fibrosis. Diagnosed early as Riedel disease, the high serum IgG4, immunohistopathology and decreased fibrosis with corticosteroid therapy, finally confirm for the first time, the origin of IgG4-RSD fibrosis of the thyroid.

Inflamed conjunctival nevi: histopathological criteria

Inflamed conjunctival nevi (ICN) may suggest malignancy because of their rapid growth and atypical histology. The objective of this study was to characterize the diagnostic features of ICN. A retrospective, nonrandomized study of 13 patients with ICN was conducted. A scoring method was developed based on histology and immunopathological parameters. The presence of epithelial solid or cystic inclusions and the preservation of goblet cells are consistent with a benign melanocytic lesion. Periodic acid-Schiff stain and immunohistochemistry to identify the epithelial component prove helpful in the differential diagnosis for melanoma. Polyclonal lymphoid infiltrate and benign cytological features of ICN exclude a diagnosis of lymphoma. Despite the presence of immunoglobulin 4-positive plasma cells in the lesions, ICN does not meet the diagnostic criteria for immunoglobulin 4-related disease. Most patients with ICN are young. The treatment for ICN is complete excision, and the prognosis is excellent.

IgG4-related disease: a new kid on the block or an old aquaintance?

IgG4-related systemic disease is a recently recognized systemic condition characterized by unique pathological features that can affect a variety of organs. It includes a growing number of medical conditions which have the following features in common: diffuse organ swelling or focal mass formation, sclerosing storiforme (whirl-shaped) fibrosis with a lymphoplasmacytic infiltrate rich in IgG4-bearing plasma cells, as well as elevated levels of serum IgG4. It invariably responds to steroid treatment and is mostly diagnosed in elderly men. Well-known syndromes like Mikulicz's disease of the salivary or lacrimal gland, Küttner's tumour of the submandibular gland, Riedel's thyroiditis, or retroperitoneal fibrosis, as well as novel entities such as autoimmune pancreatitis type 1, are now regarded to be manifestations of this systemic disease. This article provides an overview of the epidemiology, concepts of pathogenesis, clinical presentation, proposed diagnostic approaches, treatment options, and differential diagnosis of IgG4-related disease.

IgG4-related thyroiditis: a case report and review of literature

A 55-year-old male, with a positive medical history for hypothyroidism, treated with stable doses for years was admitted with subacute thyroiditis and a feeling of pain and pressure in the neck. Laboratory tests showed decrease in TSH levels, elevated erythrocyte sedimentation rate, and very high antithyroid antibodies. Owing to enlarging goiter and exacerbation in the patient's complaints, he was operated with excision of a fibrotic and enlarged thyroid lobe. Elevated IgG4 plasma levels and high IgG4/IgG plasma cell ratio on immunohistochemistry led to the diagnosis of IgG4-mediated thyroiditis. We concluded that IgG4-thyroiditis and IgG4-related disease should be considered in all patients with an aggressive form of Hashimoto's thyroiditis.

B-cell depletion attenuates serological biomarkers of fibrosis and myofibroblast activation in IgG4-related disease

OBJECTIVES

Fibrosis is a predominant feature of IgG4-related disease (IgG4-RD). B-cell depletion induces a prompt clinical and immunological response in patients with IgG4-RD, but the effects of this intervention on fibrosis in IgG4-RD are unknown. We used the enhanced liver fibrosis (ELF) score to address the impact of rituximab on fibroblast activation. The ELF score is an algorithm based on serum concentrations of procollagen-III aminoterminal propeptide, tissue inhibitor of matrix metalloproteinase-1 and hyaluronic acid.

METHODS

Ten patients with active, untreated IgG4-RD were enrolled. ELF scores were measured and correlated with the IgG4-RD Responder Index, serum IgG4, circulating plasmablasts and imaging studies. Through immunohistochemical stains for CD3, CD20, IgG4 and α-smooth muscle actin, we assessed the extent of the lymphoplasmacytic infiltration and the degree of fibroblast activation in one patient with tissue biopsies before and after rituximab.

RESULTS

The ELF score was increased in patients with IgG4-RD compared with healthy controls (8.3±1.4 vs 6.2±0.9; p=0.002) and correlated with the number of organs involved (R(2)=0.41; p=0.04). Rituximab induced significant reductions in the ELF score, the number of circulating plasmablasts and the IgG4-RD Responder Index (p<0.05 for all three parameters). Rituximab reduced both the lymphoplasmacytic infiltrate and myofibroblast activation. IgG4-RD relapse coincided with recurrent increases in the ELF score, indicating reactivation of collagen deposition.

CONCLUSIONS

The ELF score may be a clinically useful indicator of active fibrosis and the extent of disease in IgG4-RD. B-cell depletion has the potential to halt continued collagen deposition by attenuating the secretory phenotype of myofibroblasts in IgG4-RD lesions.

IgG4 antibodies in autoimmune polyglandular disease and IgG4-related endocrinopathies: pathophysiology and clinical characteristics

PURPOSE OF REVIEW

This review discusses the IgG4-related disease spectrum (IgG4-RD), the autoimmune polyglandular syndromes (APS), the association of IgG4 with APS, and possible pathobiology.

RECENT FINDINGS

IgG4-RD is a multiorgan autoimmune disorder characterized by fibrous inflammation, IgG4-positive plasma cell infiltration in affected tissues, and elevated serum concentrations of IgG4. IgG4-RD can affect any organ and has a heterogeneous presentation. Consensus criteria for diagnosis in specific organs have been established. The recognition and diagnosis of IgG4-RD are crucial because the disease responds favorably to immunosuppression (e.g., glucocorticoids, rituximab). The precise mechanisms leading to disease are unknown, but IgG4 antibodies may undergo a half antibody exchange, which renders them incapable of activating the complement pathway.

SUMMARY

Despite significant advances in disease recognition and treatment strategies, the disorder remains poorly understood. The precise role of IgG4, whether it is protective or pathogenic, is still being debated.

IgG4- related disease: an orphan disease with many faces

Immunoglobulin G4- related disease (IgG4-RD) is a rare systemic fibro-inflammatory disorder (ORPHA284264). Although patients have been described more than 100 years ago, the systemic nature of this disease has been recognized in the 21^st century only. Type 1 autoimmune pancreatitis is the most frequent manifestation of IgG4-RD. However, IgG4-RD can affect any organ such as salivary glands, orbits, retroperitoneum and many others. Recent research enabled a clear clinical and histopathological description of IgG4-RD. Typically, lymphoplasmacellular inflammation, storiform fibrosis and obliterative phlebitis are found in IgG4-RD biopsies and the tissue invading plasma cells largely produce IgG4. Elevated serum IgG4 levels are found in many but not all patients. Consequently, diagnostic criteria for IgG4-RD have been proposed recently. Treatment is largely based on clinical experience and retrospective case series. Glucocorticoids are the mainstay of therapy, although adjunctive immunosuppressive agents are used in relapsing patients. This review summarizes current knowledge on clinical manifestations, pathophysiology and treatment of IgG4-RD.

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.

Increased lymphangiogenesis in Riedel thyroiditis (Immunoglobulin G4-related thyroid disease)

The present study describes in depth a case of Riedel thyroiditis (RT) to clarify its pathogenesis and its putative inclusion in the spectrum of IgG4-related disease. We report the clinicopathological, immunohistochemical, and ultrastructural features of a case of RT in a 39-year-old white Spanish woman, admitted with a hard goiter and cold nodule in the left thyroid lobe. This case represents 0.05 % of a series of 1,973 consecutive thyroidectomies performed in our hospital. More than 80 % of the left thyroid lobe was effaced by fibrosis and inflammation (lymphocytes, 57 IgG4+ plasma cells per 1 high-power field, an IgG4/IgG ratio of 0.67, and eosinophils) with extension into the surrounding tissues and occlusive phlebitis. Immunostaining for podoplanin (D2-40) detected signs of increased lymphangiogenesis in the fibroinflammatory areas that were confirmed by electron microscopy. A strong, diffuse stain for podoplanin and transforming growth factor ß1 was also detected in the same areas. The increased number of lymphatic vessels in RT is reported for the first time. Our findings support the inclusion of RT within the spectrum of IgG4-related thyroid disease (IgG4-RTD). Although the etiology and physiopathology of IgG4-RTD still remain elusive, the results obtained in the present case suggest the participation of lymphatic vessels in the pathogenesis of RT.

Manifestations of immunoglobulin G4 related disease in otolaryngology: case reports and review of the literature

Background:

Immunoglobulin G4 related disease is an inflammatory condition characterised by the presence of fibrotic lesions infiltrated by immunoglobulin G4 positive plasma cells. It can arise from almost any region of the body and it is being increasingly recognised in the head and neck. Regardless of the site of involvement, the histopathological resemblance is remarkable. Dense lymphoplasmacytic infiltration, overabundance of immunoglobulin G4 bearing plasma cells and presence of storiform fibrosis are typical findings.

Case reports:

This paper presents two cases of immunoglobulin G4 related disease in which there was involvement of the orbit, the infraorbital nerve and the infratemporal fossa. Diagnosis was established in both cases by biopsying radiologically abnormal tissue in the infratemporal fossa.

Conclusion:

An awareness of this condition is required to establish the diagnosis and initiate appropriate therapy. Glucocorticoids are the mainstay of initial treatment. The effectiveness of B-lymphocyte depletion with rituximab has also been reported. Correct diagnosis may spare patients from unnecessarily radical surgery.

Elevated serum immunoglobulin G4 levels in patients with Graves' disease and their clinical implications

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a new clinical entity that affects various organs with increased IgG4 positive plasmacytes and progressive fibrosis. While IgG4-RDs in association with Hashimoto's thyroiditis or Riedel's thyroiditis have been reported, the relationship between IgG4-RD and Graves' disease (GD) is yet unknown. To elucidate the relation of GD to IgG4-RD, serum IgG4 levels and their clinical implications in patients with GD were investigated.

METHODS

In this prospective study, serum IgG4 levels were measured in 109 patients with GD and classified into two groups according to the comprehensive diagnostic criteria of IgG4-RD previously established: (i) GD with elevated-IgG4 levels (≥ 135 mg/dL), and (ii) GD with nonelevated IgG4 (<135 mg/dL).

RESULTS

Seven out of 109 patients with GD (6.4%) had elevated serum IgG4 levels [mean ± standard deviation (range): 175.0 ± 44.5 (136-266) mg/dL] and elevated ratios of IgG4/IgG [12.7 ± 4.5% (7.6%-21.2%)]. The remaining patients with GD had serum IgG4 levels and IgG4/IgG ratios of 39.6 ± 27.6 (3-132) mg/dL and 3.2 ± 2.2% (0.3%-11.5%), respectively. Ages in the elevated IgG4 group were significantly higher than those of the nonelevated IgG4 group: 54.7 ± 6.2 versus 43.4 ± 15.4 years, respectively. Ultrasound examinations revealed that the elevated IgG4 group had significantly increased hypoechogenic areas in the thyroid in comparison to the nonelevated IgG4 group (low echo scoring: 1.66 ± 0.81 vs. 0.61 ± 0.89, respectively). In the correlation analysis, TSAb (rs=0.385, n=42) titers were significantly correlated with se rum IgG4 levels, while they were not significantly different between the two groups. In the elevated IgG4 group, symptoms were controllable with a small dose of antithyroidal drug (ATD; n=4), a combination treatment with ATD and L-T4 (n=1), or L-T4 administration only one year after the first visit (n=2).

CONCLUSIONS

A small portion of GD patients harbored elevated serum IgG4 levels. They were older, had increased hypoechoic areas in the thyroid, and appeared to be responsive or prone to be hypothyroid after ATD treatment. Thus, the present study suggests the presence of a novel subtype of GD. Measuring serum IgG4 levels may help to distinguish this new entity and provide potential therapeutic options for GD.

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.

Serum levels of IgG and IgG4 in Hashimoto thyroiditis

Although IgG4-related disease is characterized by extensive infiltration of IgG4-positive plasma cells and lymphocytes of various organs, the details of this systemic disease are still unclear. We screened serum total IgG levels in the patients with Hashimoto thyroiditis (HT) to illustrate the prevalence of IgG4-related thyroiditis in HT. Twenty-four of 94 patients with HT (25.5%) had elevated serum IgG levels and their serum IgG4 was measured. Five of the 24 cases had more than 135 mg/dL of IgG4, which is the serum criterion of IgG4-related disease. One was a female patient who was initially treated as Graves' disease and rapidly developed a firm goiter and hypothyroidism. The biopsy of her thyroid gland revealed that follicular cells were atrophic with squamous metaplasia, replaced with fibrosis, which was compatible with the fibrous variant of HT. Immunohistochemical examination revealed diffuse infiltration of IgG4-positive plasma cells, and the serum IgG4 level was 179 mg/dL. The levels of IgG and IgG4 were positively correlated with the titers of anti-thyroglobulin antibody or anti-thyroid peroxidase antibody. In conclusion, at least a small portion of patients with HT with high titers of anti-thyroid antibodies may overlap the IgG4-related thyroiditis.

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.

Occurrence of IgG4-related hypophysitis lacking IgG4-bearing plasma cell infiltration during steroid therapy

Eight years after an episode of multiple IgG4-related disease, a pituitary mass with panhypopituitarism and a visual disturbance developed in a 70-year-old man under low-dose steroid therapy. A pituitary biopsy revealed findings of lymphocytic hypophysitis with the absence of IgG4-positive plasma cell infiltration. The serum IgG4 level was unremarkable. Although performing a pituitary biopsy and measuring the serum IgG4 level is crucial for making a diagnosis of IgG4-related hypophysitis, it is occasionally difficult to diagnose the disease in patients treated with steroid therapy, as observed in the present case. Based on a review of the diagnosis, conducting a careful assessment is required, especially in men and elderly patients thought to have solitary hypophysitis.

Solitary Lesions With Fibrosis and Increased IgG4+ Plasma Cells

We assessed 6 cases acquired during routine surgical sign-out for IgG4-related disease (IRD) according to criteria from a recent consensus meeting. These cases fulfilled the morphologic criteria—that is, dense lymphoplasmacytic infiltrates, IgG4:IgG ratio greater than or equal to 0.4, and fibrosis (storiform in 4 cases—but were associated with malignancy or did not fulfill the criteria for a new site. These criteria include increased serum IgG4 (normal in the majority of IRD) and a response to glucocorticoids, which is not appropriate treatment for resectable lesions as in our cases. Until more is known about the natural history of the disease, we propose that the possibility of an early, localized, or forme fruste of IRD should be considered and that cases associated with malignancy should at least be documented. Although we acknowledge the value of the consensus criteria, their strict application may result in missed opportunities to study the disease.

Mechanisms and assessment of IgG4-related disease: lessons for the rheumatologist

Recognition of IgG4-related disease as an independent chronic inflammatory disorder is a relatively new concept; previously, the condition was thought to represent a subtype of Sjögren's syndrome. IgG4-related disease is characterized by elevated serum levels of IgG4 and inflammation of various organs, with abundant infiltration of IgG4-bearing plasma cells, storiform fibrosis and obliterative phlebitis representing the major histopathological features of the swollen organs. The aetiology and pathogenesis of this disorder remain unclear, but inflammation and subsequent fibrosis occur due to excess production of type 2 T-helper-cell and regulatory T-cell cytokines. The disease can comprise various organ manifestations, such as dacryoadenitis and sialadenitis (also called Mikulicz disease), type 1 autoimmune pancreatitis, kidney dysfunction and lung disease. Early intervention using glucocorticoids can improve IgG4-related organ dysfunction; however, patients often relapse when doses of these agents are tapered. The disease has also been associated with an increased incidence of certain malignancies. Increased awareness of IgG4-related disease might lead to consultation with rheumatologists owing to its clinical, and potentially pathogenetic, similarities with certain rheumatic disorders. With this in mind, we describe the pathogenic mechanisms of IgG4-related disease, and outline considerations for diagnosis and treatment of the condition.

Inflammatory Abdominal Aortic Aneurysm

We report a case of an abdominal aortic aneurysm (AAA) that underwent inflammatory transformation which we treated medically with corticosteroids. Medical therapy resulted in resolution of presenting symptoms and observed inflammatory changes. We review the clinical features, associated pathology, diagnostic, and therapeutic options in the management of inflammatory AAA.

The spectrum of IgG4-related disease in the abdomen and pelvis

OBJECTIVE

IgG4-related disease was not recognized as a specific clinical entity until 2003 when extrapancreatic lesions were reported in patients with autoimmune pancreatitis. IgG4-related disease is characterized by elevated serum IgG4 levels and infiltration of the target organ by IgG4-positive plasma cells. The complete gamut of visceral involvement is still being outlined. The purpose of this article is to highlight the plethora of lesions under the spectrum of IgG4-related disease of the abdomen and pelvis, describe their imaging appearances on multimodality cross-sectional imaging, and discuss the differential diagnoses.

CONCLUSION

It is important for radiologists to recognize the multiorgan involvement and few classic features of IgG4-related disease that often tend to simulate malignancy.

The great mimicker: IgG4-related disease

IgG4-related disease is defined as a multi-organ systemic disorder with pathological findings affecting a wide range of organ systems. The condition unifies a large number of clinical diagnoses previously considered as being confined to single organ systems. At present, several issues related to its pathophysiology remained controversial, including the natural history of the disease, the pathogenic role of IgG4, and its use as a biomarker. Glucocorticoids are considered the treatment of choice for remission induction of IgG4-related disease manifestations; however, concerns regarding duration of therapy and management of refractory disease remained to be elucidated.

IgG4-related disease

The term "IgG4-related disease" encompasses several disorders described many years ago under various designations depending on the organ or system involved (e.g., Mikulicz syndrome, Riedel's thyroiditis, and retroperitoneal fibrosis). The clinical presentation varies widely, as one or more organs may be affected, usually in the same region of the body and either synchronously or metachronously. The main targets are the pancreas, bile ducts, salivary glands, lachrymal glands, mediastinal lymph nodes, and retroperitoneum. IgG4-related disease is rare, with an estimated incidence of 0.2 to 1/100,000 in Japan and no available incidence data in occidental countries. Men older than 50 years are predominantly affected. Serum IgG4 levels are often greater than 1.35 g/L. Enlargement of the involved organs, which may be pseudotumoral, is due to a combination of infiltration by T cells and IgG4-expressing plasma cells, storiform fibrosis, and obliterative thrombophlebitis. Glucocorticoid therapy is effective but may be followed by relapses requiring the use of immunomodulating agents such as azathioprine, methotrexate and, more recently, rituximab. IgG4-related disease is not an autoimmune condition related to IgG4 autoantibodies, and neither does it involve immune complexes. Specific joint involvement has been reported in a very small number of patients.

Riedel thyroiditis in a patient with graves disease

Riedel's thyroiditis is a rare form of infiltrative and inflammatory disease of the thyroid gland and can be associated with systemic fibrotic processes, Hashimoto thyroiditis and Graves disease. Riedel thyroiditis in combination with Graves disease however, is very rare. A 57-year-old woman with a past medical history significant for Graves disease diagnosed 30 years ago presented with an enlarging neck mass and voice changes. Due to suspicion of malignancy, thyroidectomy was performed. Histopathologic examination revealed Riedel thyroiditis. To our knowledge, the association of Riedel thyroiditis with Graves disease has not yet been reported in our country. Here we report a patient with Riedel thyroiditis evolved from antecedent Graves disease.