Riedel's thyroiditis association with IgG4-related disease

IgG4 serum levels in Graves' orbitopathy

OBJECTIVE

IgG4-related disease (IgG4-RD) can involve many organs, including thyroid and orbital tissues. A link between IgG4, Graves' disease (GD) and Graves' orbitopathy (GO) has been proposed, but results are conflicting. Here we investigated the possible association between IgG4 and GO.

METHODS

Retrospective investigation in 297 patients with Graves' disease (GD), 152 with GO.

PRIMARY OUTCOME

prevalence of IgG4 ≥ 135 mg/dL (cut-off for IgG4-RD).

SECONDARY OBJECTIVES

(1) serum IgG4 concentrations; (2) IgG4/IgG ratio; (3) prevalence of IgG4/IgG ratio ≥ 8.0%; (4) relationship between IgG4 and eye features; (5) relationship between IgG4 and anti-TSH receptor antibodies (TRAbs).

RESULTS

Because GO patients had lower FT3 concentrations, we evaluated the main objectives in the second and third FT3 quartiles subpopulation, in which there were no relevant differences between patients with (n = 81) or without GO (n = 67) for baseline parameters. Within this population, the prevalence of IgG4 levels ≥ 135 mg/dL did not differ between patients without and with GO (17.9% vs 17.3%). No difference was observed concerning IgG4 concentrations, prevalence of IgG4/IgG ≥ 8.0%, and IgG4/IgG ratio. There was no relationship between IgG4 and eye features and no correlation between IgG4 levels and TRAb was found.

CONCLUSIONS

Our results suggest that, within GD, there is no relationship between serum IgG4 and GO.

Advancements in diagnosing IgG4-related disease of the head and neck: Navigating diagnostic pitfalls

IgG4-related disease (IgG4-RD) is an immune-mediated condition affecting nearly any organ. This review focuses on the nuances of diagnosing IgG4-RD affecting the head and neck. Salivary gland involvement, especially of the submandibular glands, often permits a definitive diagnosis on biopsy. However, elevated IgG4+ plasma cells are nonspecific and can be seen in chronic sialadenitis, lymphoma, and other mimics. Careful correlation of clinical and pathological findings is essential. Given the significant overlap with chronic sinusitis, IgG4-RD of the sinonasal region is difficult to diagnose histologically. Laryngeal and pharyngeal involvement appears rare as an isolated finding of IgG4-RD. Mastoid disease is uncommon and remains a diagnosis of exclusion. Thyroid manifestations pose challenges given unclear diagnostic criteria - Riedel's thyroiditis likely represents IgG4-RD, but the fibrosing variant of Hashimoto's thyroiditis as a form of the so-called 'IgG4-related thyroiditis' requires better characterisation. Eosinophilic angiocentric fibrosis, despite histologic similarities, only partially overlaps with IgG4-RD. This review aims to guide diagnosing IgG4-RD in the head and neck through a systematic, organ-focused discussion of the clinical context, the utility of immunostaining, histological mimics, and controversial issues that pose diagnostic pitfalls. Increased awareness of the nuances and difficulties diagnosing IgG4-RD affecting the head and neck will improve recognition of this protean disease.

Immunoglobulin G4-related thyroiditis associated with Graves' disease: A case report

We report a case of immunoglobulin (ig)-g4-related thyroiditis associated with graves' disease. a 45-year-old man was diagnosed with graves' disease due to asymptomatic enlarged thyroid gland and high serum levels of thyrotropin receptor antibodies and thyroid hormones. surgical resection of the thyroid gland was performed because of further thyroid gland enlargement and severe fluctuations in the thyroid hormonal levels, despite medical therapy with a combination of an antithyroid drug and a thyroid hormone preparation. macroscopic examination of the resected thyroid gland revealed a grayish-white diffuse swelling, and histopathological findings revealed follicular destruction, chronic inflammatory cell infiltration with diffuse igg4-positive plasma cells (IgG4/IgG >40%), storiform fibrosis, and phlebitis obliterans throughout the thyroid tissue. Additionally, there were small foci of high columnar follicular components with scalloping, resembling Graves' disease. We propose that all patients with Graves' disease should be evaluated for coexisting IgG4-related thyroiditis to detect ophthalmopathies as soon as possible.

Our Uncommon Experience with 6 Cases of Riedel's Thyroiditis (Woody Thyroiditis)

Riedel's thyroiditis is a rare form of thyroiditis. Estimated prevalence is 1.06/100,000 population and is reported in 0.05% of thyroidectomy specimens. It has 38% association with systemic fibrotic conditions. We retrospectively reviewed 6 cases of Riedel's thyroiditis at a tertiary care centre in south India, from 2011 through 2019 with special emphasis on demography, clinical presentation, workup, management, intraoperative findings, postoperative outcomes and follow up. There were 4 females and 2 males of which we reported a rare presentation in paediatric age group which was probably never reported before. Presenting symptoms included dysphagia and compressive symptoms in neck. 5 out of 6 cases underwent surgical management- 4 total thyroidectomy and 1 hemithyroidectomy. Postoperative complications noted were temporary hypoparathyroidism, unilateral vocal cord palsy and temporary bilateral vocal cord palsy One case was medically managed with oral corticosteroids. There was no evidence of extra cervical fibrosis on follow up in all patients. There was no cause-specific mortality, and the fibrotic process stabilized or resolved in all patients. Riedel's thyroiditis is a fibroinflammatory disorder presenting with compressive symptoms mandating surgical intervention mainly decompression in the form of isthmectomy. However since extensive interventions are associated with complications it is less favoured approach. Long term follow up of these cases are necessary for detecting evidence of extra cervical fibrosis.

IgG4-positive Hashimoto thyroiditis and its association with IgG4-related sclerosing disease

A woman in her 50s was referred with suspected thyroid malignancy and underwent total thyroidectomy. Immunohistochemical analysis revealed IgG4-positive Hashimoto's thyroiditis. IgG4-related thyroid disease is poorly understood, and thought to encompass various entities including IgG4-positive Hashimoto's thyroiditis, Fibrosing Variant of Hashimoto's thyroiditis, Reidel's thyroiditis and Graves' disease with elevated IgG4 levels. Furthermore, it may be associated with a systemic fibrosing condition called 'IgG4-related sclerosing disease'. The clinical significance of IgG4-positive thyroid disease, however, remains unclear.

Immunoglobulin G4-Related Thyroid Disease: A Single-Center Experience and Literature Review

BACKGROUND

Immunoglobulin G4 (IgG4)-related disease is an entity that can involve the thyroid gland. The spectrum of IgG4-related thyroid disease (IgG4-RTD) includes Hashimoto thyroiditis (HT) and its fibrotic variant, Riedel thyroiditis, as well as Graves' disease. The early diagnosis of IgG4-RTD is important because it is a medically treatable disease, and a delay in the diagnosis might result in unnecessary surgery. We present a case series of IgG4-RTD with a review of the literature.

METHODS

We retrospectively reviewed the clinical presentation and the radiological and pathological findings of patients diagnosed with IgG4-RTD between 2017 and 2021 at a tertiary medical center in Korea. We also conducted a literature review of IgG4-RTD.

RESULTS

Five patients were diagnosed with IgG4-RTD during the study period. The patients' age ranged from 31 to 76 years, and three patients were men. Most patients visited the clinic for a neck mass, and hypoechogenic nodular lesions were observed on neck ultrasonography. Three patients had IgG4 HT, and two patients had IgG4 Riedel thyroiditis. All patients developed hypothyroidism that necessitated L-thyroxine replacement. The diagnosis of IgG4-RTD was confirmed after a pathological examination of the surgical specimen in the first two cases. However, the early diagnosis was possible after a core needle biopsy in three clinically suspected patients.

CONCLUSION

The diagnosis of IgG4-RTD requires clinical suspicion combined with serology and histological analyses using IgG4 immunostaining. The early diagnosis of IgG4-RTD is difficult; thus, biopsy with IgG4 immunostaining and serum IgG4 measurements will help diagnose patients suspected of having IgG4-RTD.

IgG4-related disease. Clinical manifestation differential diagnosis and recent International Diagnostic Criteria for IgG4-related disease

Immunoglobulin G4- related disease (IgG4-RD) is a rare systemic fibro-inflammatory disorder. Autoimmune pancreatitis is the most frequent manifestation of IgG4-RD. However, IgG4-RD can affect any organ such as salivary glands, orbits, retroperitoneum, prostate and many others. Recent research enabled a clear clinical and histopathological description of IgG4-RD and in 2019 four Clinical phenotypes of IgG4-related disease were described. Diagnosis is based on morphological examination with typical findings of lymphoplasmocellular inflammation, storiform fibrosis and obliterative phlebitis 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. New diagnostic criteria for IgG4-RD have been published recently in 2019 and 2021. This review summarizes current knowledge on pathophysiology, clinical manifestations, diagnosis and differential diagnosis of IgG4-RD from the point of view 2022 and in next article brings overview of the IgG4-RD therapy.

[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.

Clinical Perspectives on IgG4-Related Disease and Its Classification

Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated fibroinflammatory disease. Since its discovery nearly two decades ago, our understanding of its pathophysiology and clinical manifestations has grown substantially. Early diagnosis and treatment of this elusive disease can prevent substantial organ damage from end-stage fibrosis, emphasizing the need for prompt recognition and accurate characterization of IgG4-RD. The classification criteria endorsed by the American College of Rheumatology and the European Alliance of Associations for Rheumatology in 2019 provide a framework for establishing the diagnosis in the clinical setting. This process involves recognizing the typical manifestations of the disease and incorporating clinical, radiological, serological, and histopathological information as well as excluding disease mimickers. Glucocorticoids and rituximab are effective at inducing remission in IgG4-RD in most patients, but the optimal approach to long-term management of IgG4-RD remains an area of active clinical research. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

IgG4-Related Retroperitoneal Fibrosis: A Rare Association With Riedel's Thyroiditis

Idiopathic retroperitoneal fibrosis is a rare fibro-inflammatory disease that can be associated with other IgG4-related diseases (IgG4-RDs). It is exceedingly uncommon to encounter this condition in a patient with Riedel's thyroiditis (RT), another disease in the IgG4-RD family. We present the case of a 53-year-old man with a history of RT who presented for severe localized lower abdominal and suprapubic pain due to obstructive uropathy from extensive retroperitoneal fibrosis. The biopsy of the mass demonstrated fibro-inflammatory tissue, and its immunohistochemistry was notable for IgG4-positive plasma cells. This case highlights the challenge associated with the diagnosis and management of this rare manifestation of IgG4-RD. In a patient with a history of any form of IgG4-RDs, providers should be vigilant for any signs or symptoms that suggest the development of fibrosis in other organs.

IgG4-related disease of the thyroid gland

IgG4-thyroid-related disease (TRD) represents an uncommon spectrum of diseases, with four subcategories established so far, IgG4-related Hashimoto's thyroiditis, fibrosing variant of Hashimoto's thyroiditis, Riedel's thyroiditis and Graves disease with elevated IgG4 levels. We report the case of a 59-year-old woman presenting with painless cervical swelling and hypothyroidism. Thyroid gland was enlarged and distinctively very hard, with reduced mobility. Neck ultrasonography showed multiple nodularity and diffuse thyroid enlargement, which on CT scan conditioned slight deviation of the airway. Fine-needle aspiration of the biggest nodule was suggestive of lymphocytic thyroiditis. She developed compressive symptoms and was submitted to total thyroidectomy. Histology of the thyroid revealed extensive areas of fibrosis, oncocytic cells and lymphoplasmacytic infiltrates. Immunohistochemistry confirmed the predominance of IgG4-secreting plasma cells. IgG4-TRD is characterised by a rapidly progressive and destructive thyroiditis process. Typical presentation can often mimic malignancy; hence, an opportune recognition of IgG4-TRD may avoid unnecessary burdens.

The American Association of Endocrine Surgeons Guidelines for the Definitive Surgical Management of Thyroid Disease in Adults

OBJECTIVE

To develop evidence-based recommendations for safe, effective, and appropriate thyroidectomy.

BACKGROUND

Surgical management of thyroid disease has evolved considerably over several decades leading to variability in rendered care. Over 100,000 thyroid operations are performed annually in the US.

METHODS

The medical literature from 1/1/1985 to 11/9/2018 was reviewed by a panel of 19 experts in thyroid disorders representing multiple disciplines. The authors used the best available evidence to construct surgical management recommendations. Levels of evidence were determined using the American College of Physicians grading system, and management recommendations were discussed to consensus. Members of the American Association of Endocrine Surgeons reviewed and commented on preliminary drafts of the content.

RESULTS

These clinical guidelines analyze the indications for thyroidectomy as well as its definitions, technique, morbidity, and outcomes. Specific topics include Pathogenesis and Epidemiology, Initial Evaluation, Imaging, Fine Needle Aspiration Biopsy Diagnosis, Molecular Testing, Indications, Extent and Outcomes of Surgery, Preoperative Care, Initial Thyroidectomy, Perioperative Tissue Diagnosis, Nodal Dissection, Concurrent Parathyroidectomy, Hyperthyroid Conditions, Goiter, Adjuncts and Approaches to Thyroidectomy, Laryngology, Familial Thyroid Cancer, Postoperative Care and Complications, Cancer Management, and Reoperation.

CONCLUSIONS

Evidence-based guidelines were created to assist clinicians in the optimal surgical management of thyroid disease.

Hashimoto's Thyroiditis with Increased IgG4-Positive Plasma Cells: Using Thyroid-Specific Diagnostic Criteria May Identify Early Phase IgG4 Thyroiditis

Background: A subset of Hashimoto's thyroiditis (HT), reported as immunoglobulin G4 (IgG4) thyroiditis, is characterized by IgG4+ plasma cell-rich inflammation and marked sclerotic changes, which suggests a close relationship with immunoglobulin G4-related disease (IgG4-RD). However, to date, there is no consensus regarding the cutoff values used to define a significant IgG4+ plasma cell count in thyroid inflammation. We, therefore, sought to validate both the cutoff value of the comprehensive diagnostic criteria (CVC) and the cutoff value of thyroid-specific diagnostic criteria (CVT) for diagnosing IgG4 thyroiditis. Methods: One hundred twenty cases of HT were retrospectively reviewed. According to the CVC (IgG4+ plasma cells >10/HPF (high-power field) and IgG4+/IgG+ plasma cell ratio >40%) and the CVT (IgG4+ plasma cells >20/HPF and IgG4+/IgG+ plasma cell ratio >30%), cases were subclassified as IgG4 thyroiditis or non-IgG4 thyroiditis. Clinical, serological, sonographic, and histopathological characteristics of the two subsets, and the cases diagnosed as IgG4 thyroiditis using different thresholds were compared. Results: Both the CVC and CVT identified the same set of distinct clinical, laboratory, and sonographic features of the cases diagnosed as IgG4 thyroiditis. All 120 cases of HT were able to be divided into four distinct groups. Group A included the 25 cases who were assigned as IgG4 thyroiditis by both the CVC and CVT, whereas Group D included the 85 cases who did not meet either of the cutoff values. Group B and Group C comprised the borderline cases who only met one of the two thresholds. Based on histological evaluation, the cases in Group B who met the CVT demonstrated similar histological features of IgG4 thyroiditis. Conclusions: Although both of the cutoff values can efficiently distinguish IgG4 thyroiditis from its non-IgG4 counterpart, the thyroid-specific cutoff value (CVT, IgG4+ plasma cells >20/HPF, and IgG4+/IgG+ plasma cell ratio >30%) can better identify borderline cases of HT with more fibrotic changes, which may represent an early phase lesion of IgG4 thyroiditis. We propose a new series of clinical and pathological diagnostic clues for both endocrinologists and pathologists to improve the early recognition of IgG4 thyroiditis.

Comprehensive research on thyroid diseases associated with autoimmunity: autoimmune thyroid diseases, thyroid diseases during immune-checkpoint inhibitors therapy, and immunoglobulin-G4-associated thyroid diseases

Various thyroid diseases are associated with autoimmunity. Major autoimmune thyroid diseases are Graves' disease (GD) and Hashimoto's thyroiditis (HT). Thyrotropin receptor is an autoantigen in GD, and its immunogenicity has been examined. Immune-checkpoint inhibitor (ICI) is recently widely used for treatment of malignant tumors, but cases of thyroid diseases during ICI treatment have been increasing. Thyroid diseases during ICI therapy have been investigated in immunological and clinical aspects, and their Japanese official diagnostic guidelines were established. In addition, serum and tissue immunoglobulin-G4 levels have been examined in association with clinicopathological characteristics in GD, HT, and Riedel's thyroiditis. We review these diseases associated with thyroid autoimmunity and comprehensively discuss their potential application in future research and therapeutic options.

DIAGNOSIS OF ENDOCRINE DISEASE: IgG4-related thyroid autoimmune disease

IgG4-related disease (IgG4-RD) is fibro-inflammatory, immune-mediated, systemic disease recognized as a defined clinical condition only in 2001. The prevalence of IgG4-RD is 6/100 000, but it is likely to be underestimated due to insufficient awareness of the disease. The diagnostic approach is complex because of the heterogeneity of clinical presentation and because of rather variable diagnostic criteria. Indeed, high concentrations of IgG4 in tissue and serum are not a reliable diagnostic marker. The spectrum of IgG4-RD also includes well-known thyroid diseases including Riedel's thyroiditis, Hashimoto's thyroiditis and its fibrotic variant, Graves' disease and Graves' orbitopathy. Results from clinical studies indicate that a small subset of patients with the above-mentioned thyroid conditions present some features suggestive for IgG4-RD. However, according to more recent views, the use of the term thyroid disease with an elevation of IgG4 rather than IgG4-related thyroid diseases would appear more appropriate. Nevertheless, the occurrence of high IgG4 levels in patients with thyroid disease is relevant due to peculiarities of their clinical course.

Parathyroid adenoma with prominent lymphocytic infiltrate having histological features highly suggestive of IgG4-related disease: a case report and literature review

Parathyroid adenoma with prominent lymphocytic infiltrate is a rare disease. Until now, 11 patients have been reported. Herein, we report a 57-year-old man who had a neck mass that was incidentally found. Aspiration cytology and subsequent needle biopsy of the tumor were performed and suggested papillary thyroid carcinoma. From the resected specimen, however, the patient was finally diagnosed with parathyroid adenoma with prominent lymphocytic infiltrate, characterized by hyperplastic parathyroid cells with nuclear atypia within fibrotic stroma along with numerous lymphocytes forming germinal centers. Some eosinophils and plasma cells were also observed with some histological features highly suggestive of IgG4-related disease (IgG4-RD), including increased IgG4-positive plasma cells and IgG4/IgG-positive plasma cell ratio, storiform-type fibrosis, and obliterative phlebitis. It turned out that microfollicular or trabecular architecture and cellular atypia with high expression of HBME-1 observed in the aspiration cytology and needle biopsy had been misinterpreted as a thyroid malignancy. This is the first report describing microscopic features of aspiration cytology and needle biopsy of parathyroid adenoma with prominent lymphocytic infiltrate, warning that it can mimic papillary thyroid carcinoma in biopsy specimens. Furthermore, the IgG4-RD-like features of the present case and previous reports imply that parathyroid adenoma with prominent lymphocytic infiltrate may be a type of IgG4-RD.

Immunohistochemical Biomarkers in Diagnosis of Hematolymphoid Neoplasms of Endocrine Organs

The hematolymphoid infiltrations are challenging lesions in endocrine organs and tissues. The fourth edition of WHO classification of tumors of endocrine organs and the fourth edition of WHO classification of tumors of hematopoietic and lymphoid tissues are recently published. The updates in both fields include some new disease descriptions and prognostic markers. Our aim in this review article is to give practical diagnostic information about the most frequently seen hematolymphoid involvements of the pituitary gland, thyroid, and adrenal tissue. We designed the text in the order of organs and the contents according to the disease frequency. The pituitary gland and cellar region are the most frequently involved with Langerhans cell histiocytosis. Although it is very rare, Erdheim-Chester disease has recently been included in the classification and still needs more clear diagnostic definitions. Lymphoproliferative thyroid lesions and presentations create diagnostic problems for the pathologists. IGG4-related disease and its relation with thyroiditis is a new concept. There are many unknowns on pathobiology of the disease spectrum and discussion on defined diagnostic criteria of the IGG4-related thyroid diseases. The overlapping features of thyroiditis and primary thyroid lymphomas also create diagnostic difficulties. The frequently recognized primary hematolymphoid lesions of the endocrine organs may not be difficult to diagnose since they are expected lesions. The secondary involvement of hematolymphoid neoplasia may be more difficult to diagnose for an endocrine pathologist. In this review article, we aim to give brief description of the diseases and practical diagnostic approach by using optimum markers guided by the latest WHO classifications.

IgG4-Related Disease of the Thyroid Gland Requiring Emergent Total Thyroidectomy: A Case Report

IgG4-related disease of the thyroid gland is a recently recognized subtype of thyroiditis, often with rapid progression requiring surgical treatment. It is considered as a spectrum of disease varying from early IgG4-related Hashimoto's thyroiditis (HT) pattern to late fibrosing HT or Riedel's thyroiditis patterns. Here, we report a 47-year-old Malay woman presenting with progressively painless neck swelling over 3 years and subclinical hypothyroidism. Computed tomography (CT) scan revealed diffuse thyroid enlargement (up to 13 cm) with retrosternal extension and without regional lymphadenopathy. Fine needle aspiration of the thyroid showed a limited number of follicular epithelial cell groups with widespread Hurthle cell change and scanty background colloid, but no evidence of lymphocytosis. The cytologic features fell into the category of 'atypia of undetermined significance'. Subsequently, the patient developed hypercapnic respiratory failure secondary to extrinsic upper airway compression by the thyroid mass and underwent emergent total thyroidectomy. Histology of the thyroid showed diffuse dense lymphoplasmacytic infiltrate and fibrosis. Follicular cells exhibited reactive nuclear features and some Hurthle cell change. IgG4+ plasma cells were over 40/high power field while overall IgG4/IgG ratio was above 50%. The overall features suggest the diagnosis of IgG4-related disease of the thyroid gland in the form of IgG4-related HT. Post-surgery, the patient was found to have markedly elevated serum IgG4 concentration but PET/CT did not show significant increased fludeoxyglucose uptake in other areas. Her recovery was complicated by a ventilator-associated pneumonia with empyema, limiting early use of corticosteroids for treatment of IgG4-related disease.

Riedel's thyroiditis: clinical presentation, treatment and outcomes

BACKGROUND

Riedel´s thyroiditis (RT) is a rare inflammatory disease of the thyroid gland, causing compression and fibrosis of adjacent tissues. Typically the goiter is hard and firm. Hoarseness, dyspnea, and dysphagia may be present.

METHODS

We retrospectively reviewed all patients known by us with RT in addition to all patients with appropriate ICD-10 codes evaluated at the Karolinska University Hospital 2003-2015. Clinical, biochemical, and histological data of patients with RT were recorded in detail. Histological preparations were re-examined when available.

RESULTS

RT was diagnosed in six patients. Five were females and the median age at first presentation was 50 years (25-81 years). Median follow-up time was 3.75 years (1-22 years). At diagnosis five had hypothyroidism. Four had extrathyroidal manifestations, and one of these had also distant fibrosis. One patient had a clear IgG4/IgG ratio over 40%. One patient was treated with tracheostomy, one with isthmectomy and one with total thyroidectomy. Four had been treated with glucocorticoids, four with tamoxifen, and two with both drugs. One had also been treated with mycophenolate mofetil combined with Rituximab. At the end of follow-up four was doing fine, one had recurrent episodes of inflammation and one had died of possible complications to RT.

CONCLUSION

It is important to recognize RT and give adequate treatment. Steroids are still the mainstay of therapy but other medications against fibrosclerosis can be considered. Wakefulness of other fibrosing manifestations is essential. Immunohistochemistry can show whether IgG-4 plasma cells are increased which could lead to fibrosis in other organs.

Clinical Implications of Immunoglobulin G4 to Graves' Ophthalmopathy

BACKGROUND

This study aimed to explore the relation of immunoglobulin G4 (IgG4) to clinical and laboratory characteristics of patients newly diagnosed with Graves' disease (GD) without or with Graves' ophthalmopathy (GO) and to analyze association of IgG4 with development and grade of GO in GD patients.

METHODS

Sixty-four GD patients and 64 sex- and age-matched euthyroid subjects were enrolled. Serum levels of thyroid hormones, thyroid autoantibodies, immunoglobulin G (IgG), and IgG4 were measured, and ophthalmological and ultrasonographical evaluation was performed.

RESULTS

In GD patients compared with euthyroid subjects, levels of thyroid hormones, thyroid autoantibodies and IgG4 as well as the IgG4/IgG ratio were elevated. GD patients having GO in comparison to not having GO were characterized by a female predominance; a high incidence of smoking history; high levels of T3, free T4, TSH receptor autoantibody (TRAb) and IgG4; and a high IgG4/IgG ratio after adjusting for sex. In GD patients, the IgG4 level was the independent factor associated with GO development on multivariate analysis. When severity and activity of GO were classified using the European Group on Graves' Orbitopathy criteria in GD patients with GO, IgG4 levels and IgG4/IgG ratio were elevated in the moderate-to-severe group compared with the mild group and in the active group compared with the inactive group. IgG4 levels and IgG4/IgG ratio became elevated as clinical activity score increased. IgG4 levels were positively correlated with TRAb levels. The high IgG4 group in comparison to the normal IgG4 group had a high incidence of family history of autoimmune thyroid disease, high levels of free T4, TRAb and IgG4, a high IgG4/IgG ratio and extensive hypoechogenicity.

CONCLUSIONS

These results suggest that IgG4 levels are elevated in newly diagnosed GD patients compared with euthyroid subjects and in the presence of GO compared with the absence of GO. Moreover, our findings suggest that IgG4 levels are associated with the development and grade of GO in GD patients.

Immunoglobulin G4-Related Thyroid Diseases

Immunoglobulin G4-related disease (IgG4-RD) is a new disease category involving many organ systems, including the endocrine system in general and the thyroid in particular. Since an initial association was made between hypothyroidism and autoimmune (IgG4-related) pancreatitis, more forms of IgG4-related thyroid disease (IgG4-RTD) have been recognized. Four subcategories of IgG4-RTD have so far been identified: Riedel thyroiditis (RT), fibrosing variant of Hashimoto thyroiditis (FVHT), IgG4-related Hashimoto thyroiditis, and Graves disease with elevated IgG4 levels. Although a male predominance is seen for IgG4-RD in general, RT and FVHT have a female preponderance. The pathogenesis of IgG4-RD is not completely understood; however, genetic factors, antigen-antibody reactions, and an allergic phenomenon have been described. Diagnosis of IgG4-RD requires a combination of clinical features, serological evidence, and histological features. Histology is the mainstay of diagnosis, with IgG4 immunostaining. Although serum IgG4 levels are usually elevated in IgG4-RD, raised serum IgG4 is neither necessary nor adequate for diagnosis. Imaging supports the diagnosis and is a useful tool in disease monitoring. Management of IgG4-RTD is both medical and surgical. Steroids are the first-line treatment and may produce a swift response. Tamoxifen and rituximab are second-line agents used in steroid-resistant patients. Surgical debulking is carried out in RT solely as a procedure to relieve obstruction. Other endocrine associations described with IgG4-RD are hypophysitis and Hashimoto encephalopathy. IgG4-RTD is an uncommon disease entity, and prompt diagnosis and treatment can improve outcomes.