Immunohistochemistry of IgG4 can help subclassify Hashimoto's autoimmune thyroiditis

Predicting autoimmune thyroiditis in primary Sjogren's syndrome patients using a random forest classifier: a retrospective study

BACKGROUND

Primary Sjogren's syndrome (pSS) and autoimmune thyroiditis (AIT) share overlapping genetic and immunological profiles. This retrospective study evaluates the efficacy of machine learning algorithms, with a focus on the Random Forest Classifier, to predict the presence of thyroid-specific autoantibodies (TPOAb and TgAb) in pSS patients.

METHODS

A total of 96 patients with pSS were included in the retrospective study. All participants underwent a complete clinical and laboratory evaluation. All participants underwent thyroid function tests, including TPOAb and TgAb, and were accordingly divided into positive and negative thyroid autoantibody groups. Four machine learning algorithms were then used to analyze the risk factors affecting patients with pSS with positive and negative for thyroid autoantibodies.

RESULTS

The results indicated that the Random Forest Classifier algorithm (AUC = 0.755) outperformed the other three machine learning algorithms. The random forest classifier indicated Age, IgG, C4 and dry mouth were the main factors influencing the prediction of positive thyroid autoantibodies in pSS patients. It is feasible to predict AIT in pSS using machine learning algorithms.

CONCLUSIONS

Analyzing clinical and laboratory data from 96 pSS patients, the Random Forest model demonstrated superior performance (AUC = 0.755), identifying age, IgG levels, complement component 4 (C4), and absence of dry mouth as primary predictors. This approach offers a promising tool for early identification and management of AIT in pSS patients.

TRIAL REGISTRATION

This retrospective study was approved and monitored by the Ethics Committee of The Third Affiliated Hospital of Sun Yat-sen University (No.II2023-254-02).

A machine learning-based diagnosis modeling of IgG4 Hashimoto's thyroiditis

PURPOSE

This study aims to develop a non-invasive diagnosis model using machine learning (ML) for identifying high-risk IgG4 Hashimoto's thyroiditis (HT) patients.

METHODS

A retrospective cohort of 93 HT patients and a prospective cohort of 179 HT patients were collected. According to the immunohistochemical and pathological results, the patients were divided into IgG4 HT group and non-IgG4 HT group. Serum TgAb IgG4 and TPOAb IgG4 were detected by ELISAs. A logistic regression model, support vector machine (SVM) and random forest (RF) were used to establish a clinical diagnosis model for IgG4 HT.

RESULTS

Among these 272 patients, 40 (14.7%) were diagnosed with IgG4 HT. Patients with IgG4 HT were younger than those with non-IgG4 HT (P < 0.05). Serum levels of TgAb IgG4 and TPOAb IgG4 in IgG4 HT group were significantly higher than those in non-IgG4 HT group (P < 0.05). There were no significant differences in gender, disease duration, goiter, preoperative thyroid function status, preoperative TgAb or TPOAb levels, and thyroid ultrasound characteristics between the two groups (all P > 0.05). The accuracy, sensitivity, and specificity were 57%, 78%, and 79% for logistic regression model of IgG4 HT, 80 ± 7%, 84.7% ± 2.6%, and 75.4% ± 9.6% for the RF model and 78 ± 5%, 89.8% ± 5.7%, and 64.7% ± 5.7% for the SVM model. The RF model works better than SVM. The area under the ROC curve of RF ranged 0.87 to 0.92.

CONCLUSION

A clinical diagnosis model for IgG4 HT established by RF model might help the early recognition of the high-risk patients of IgG4 HT.

Are sonographic characteristics of Hashimoto's thyroiditis related with immunologic parameters? A cross-sectional study

BACKGROUND

The clinical, laboratory, and imaging characteristics of Hashimoto's thyroiditis are widely recognized. However, there is a dearth of information concerning the relationship between these aspects. The primary objective of this study was to investigate the correlation between sonographic features and immunologic parameters in individuals with Hashimoto's thyroiditis.

METHODS

This cross-sectional study enrolled a cohort of 100 consecutive patients diagnosed with Hashimoto's thyroiditis. Ultrasonography was performed to classify thyroid gland characteristics, including parenchymal heterogeneity (mild/moderate-to-high), extent of fibrosis (none-to-mild/moderate-to-high), and volume (atrophic/non-atrophic). As for immunologic parameters, thyroid autoantibodies (TOA; anti-TPO and anti-Tg), along with IG (immunoglobulin) G4 levels and lymphocyte subsets, were assessed.

RESULTS

Of the 100 patients evaluated, 88 were female (88%) and 12 were male (12%). IgG4/IgG ratio and weekly levothyroxine (LT4) dose were significantly higher in the group with moderate-to-high heterogeneity than the group with mild parenchymal heterogeneity (p = 0.043 and p < 0.001, respectively). Compared to the group with none-to-mild fibrosis, the anti-TPO, IgG4, IgG4/IgG ratio and LT4 dose were significantly higher in the moderate-to-high fibrosis group. Anti-TPO and IgG levels were significantly lower in the atrophic thyroid group compared to the non-atrophic thyroid group. Although not reaching statistical significance, the proportion of plasma cells in the moderate/high fibrosis group was higher than in the non-fibrosis/mild fibrosis group. There was a moderate positive correlation between fibrosis with Anti-TPO, and a low positive correlation between anti-Tg, IgG4 levels with IgG4/IgG ratio.

CONCLUSION

TOA, Ig G4 levels and severity of hypothyroidism were associated with ultrasonographic features such as parenchymal heterogeneity and fibrosis in Hashimoto's thyroiditis.

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.

Utilizing Immunoglobulin G4 Immunohistochemistry for Risk Stratification in Patients with Papillary Thyroid Carcinoma Associated with Hashimoto Thyroiditis

BACKGRUOUND

Hashimoto thyroiditis (HT) is suspected to correlate with papillary thyroid carcinoma (PTC) development. While some HT cases exhibit histologic features of immunoglobulin G4 (IgG4)-related disease, the relationship of HT with PTC progression remains unestablished.

METHODS

This cross-sectional study included 426 adult patients with PTC (≥1 cm) undergoing thyroidectomy at an academic thyroid center. HT was identified based on its typical histologic features. IgG4 and IgG immunohistochemistry were performed. Wholeslide images of immunostained slides were digitalized. Positive plasma cells per 2 mm2 were counted using QuPath and a pre-trained deep learning model. The primary outcome was tumor structural recurrence post-surgery.

RESULTS

Among the 426 PTC patients, 79 were diagnosed with HT. With a 40% IgG4 positive/IgG plasma cell ratio as the threshold for diagnosing IgG4-related disease, a cutoff value of >150 IgG4 positive plasma cells per 2 mm2 was established. According to this criterion, 53% (43/79) of HT patients were classified as IgG4-related. The IgG4-related HT subgroup presented a more advanced cancer stage than the IgG4-non-related HT group (P=0.038). The median observation period was 109 months (range, 6 to 142). Initial assessment revealed 43 recurrence cases. Recurrence-free survival periods showed significant (P=0.023) differences, with patients with IgG4 non-related HT showing the longest period, followed by patients without HT and those with IgG4-related HT.

CONCLUSION

This study effectively stratified recurrence risk in PTC patients based on HT status and IgG4-related subtypes. These findings may contribute to better-informed treatment decisions and patient care strategies.

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.

Reshaping the Concept of Riedel's Thyroiditis into the Larger Frame of IgG4-Related Disease (Spectrum of IgG4-Related Thyroid Disease)

Recently, Riedel's thyroiditis (RT) was assimilated into the larger spectrum of immunoglobulin IgG4-related disease (IgG4-RD) in addition to a particular frame of IgG4-related thyroid disease (IgG4-RTD), underlying IgG4-RT, IgG4-associated Hashimoto's thyroiditis (and its fibrotic variant), and IgG4-related Graves's disease. Our objective was to overview recent data on RT, particularly IgG4-RD and IgG4-RTD. The case and study- sample analysis (2019-2023) included 293 articles and selected 18 original studies: nine single case reports (N = 9, female/male = 2/1, aged: 34-79 years, 5/9 patients with serum IgG4 available data, 2/5 with high serum IgG4) and four case series (N = 21; 4/5 series provided data on IgG4 profile, 3/21 had serum IgG4 assays, and 2/3 had abnormally high values). IgG4-RD and thyroid findings were analyzed in three cohorts (N = 25). Another two studies (N = 11) specifically addressed IgG4-RTD components. On presentation, the patients may have hypothyroidism, transitory thyrotoxicosis, goiter, long-term history of positive anti-thyroid antibodies, and hypoechoic ultrasound thyroid pattern. The 5-year analysis (N = 66) showed the rate of serum IgG4 evaluation remained low; normal values do not exclude RT. Mandatory histological and immunohistochemistry reports point out a high content of IgG4-carrying plasma cells and IgG4/IgG ratio. Unless clinically evident, histological confirmation provides a prompt indication of starting corticoid therapy since this is the first-line option. Surgery, if feasible, is selective (non-responders to medical therapy, emergency tracheal intervention, and open/core needle biopsy). Current open issues are identifying the role of serum IgG4 assays in patients with IgG4-RD, finding out if all cases of RT are IgG4-mediated, applying IgG4-RTD criteria of differentiation among four entities, and providing an RT/IgG4-RTD guideline from diagnosis to therapy. It remains that the central aim of approaching RT in daily practice is the early index of suspicion in order to select patients referred for further procedures that provide enough histological/immunohistochemistry material to confirm RT and its high IgG4 burden.

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.

Clinical differences between IgG4 Hashimoto's thyroiditis and primary thyroid lymphoma

Background

Hashimoto's thyroiditis (HT) can be divided into IgG4 HT and non-IgG4 HT based on IgG4 and IgG immunohistochemical staining. In clinical practice, it is often necessary to identify diseases such as primary thyroid lymphoma (PTL) and IgG4 HT when a patient presents with a rapidly enlarged thyroid. The aim of our study was to uncover the differential points between the two diseases.

Methods

Clinical information from 19 IgG4 HT and 10 PTL patients was obtained from the patients' medical records, including age, sex, main clinical manifestation, thyroid functional status, the presence of serum anti-thyroid peroxidase antibodies, anti-thyroglobulin antibodies, and thyroid ultrasonography results. Thyroid sections from all patients were collected to detect IgG4 and IgG expression by immunohistochemical staining.

Results

The IgG4 HT patients were significantly younger than those in the PTL group (39.68 ± 10.95 vs 66.20 ± 10.23 years, P < 0.001). There were no significant differences in the sex distribution or TgAb- or TPOAb-positive rates. The PTL group had a higher prevalence of clinical hypothyroidism than the IgG4 HT group (P = 0.016). In the PTL group, thyroid lesions were more likely to exhibit hypoechogenicity (6/6 vs 1/19, P < 0.001) on ultrasound images. In the PTL group, two patients met the immunohistochemical cut-off value of the criteria for IgG4 HT.

Conclusions

Simply relying on immunohistochemistry for IgG4 cannot diagnose IgG4 HT correctly when a patient presents with rapid thyroid enlargement. A combination of clinical and pathological analyses will help distinguish IgG4 HT from PTL which may be with abundant IgG4-positive plasma cells.

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.

The characteristics and clinical significance of elevated serum IgG4/IgG levels in patients with Graves' disease

PURPOSE

This study aims to further explore the clinical and laboratory characteristics of patients with GD with high serum IgG4 based on the IgG4/IgG ratio.

METHODS

This study is a prospective observational study. A total of 25 normal controls and 84 people newly diagnosed with GD were enrolled in this study. Taking the IgG4/IgG ratio of 8% as the cutoff value, the experimental groups were further divided into two subgroups: the high IgG4/IgG subgroup and the normal IgG4/IgG subgroup. We evaluated the differences in clinical characteristics and laboratory parameters between the groups.

RESULTS

The IgG4, IgG4/IgG, and IL-17 of the newly diagnosed GD group were significantly higher than those of the normal control group (P < 0.05). The differences in age, IL-1β, IL-17, and eosinophil count between the high IgG4/IgG subgroup and the normal IgG4/IgG subgroup were statistically significant (P < 0.05). After ATD treatment, some patients developed allergies; the high IgG4/IgG subgroup was significantly higher than the normal IgG4/IgG subgroup (χ2 = 4.424, P = 0.035). After 3 months of ATD treatment in patients with GD, the TRAb in the normal IgG4/IgG subgroup were significantly lower than before (P < 0.05), while the difference in the high IgG4/IgG subgroup was not statistically significant (P > 0.05).

CONCLUSIONS

A small portion of patients with GD harbored elevated serum IgG4/IgG levels. They are younger, have higher eosinophils, and are more prone to allergies; also, they have higher levels of cytokines IL-1β and IL-17 and their remission is not easily attained after treatment with ATD; this could be due to the instability of the Th17/Treg cell balance.

Review of IgG4-related Hashimoto Thyroiditis With Best Practice Recommendations for Diagnosis and Reporting

Found in virtually any organ system, immunoglobulin (Ig) G4-related disease (RD) is a recently recognized immune-mediated, systemic, a fibroinflammatory disease characterized histologically by storiform fibrosis, obliterative phlebitis, and lymphoplasmacytic infiltrate with IgG4-positive plasma cells (PCs). IgG4-related Hashimoto thyroiditis (IgG4-RHT), also called IgG4-related thyroiditis, shares many features with IgG4-RD but is distinct in several ways. A case of IgG4-RHT in a 51-year-old African American female is assembled together with a literature review which uncovered 82 cases of IgG4-RHT. The findings and criteria which the respective authors used to reach their diagnoses are analyzed. Findings common to all studies are lymphoplasmacytic infiltration and IgG4-positive staining, while most describe follicular atrophy (95.2%, 79/83). Stromal fibrosis involving >33% of thyroid architecture was reported in 74% (58/78) of cases. While few reports observed storiform fibrosis, all describe lack of obliterative phlebitis or systemic involvement. Discrepancies between reports exist in immunostaining thresholds, as well as grading systems for stromal fibrosis. Based on our review of the literature and experience, we propose a set of best practice recommendations for the diagnosis of IgG4-RHT. Our diagnostic criteria are (1) lack of extrathyroidal IgG4-RD, (2) the fibroinflammatory process should not extend beyond the thyroid capsule, (3) stromal fibrosis comprises at least 30% of the involved tissue, (4) >30% IgG4/IgG ratio, with absolute immunostaining cutoffs varying by the degree of stromal fibrosis: for >50% stromal fibrosis use >20 IgG4+PCs/HPF, for 30% to 50% fibrosis use >30 IgG4+PCs/HPF, (5) fibrosis infiltrates the interlobular/interfollicular space, (6) features of follicle injury, and (7) obliterative phlebitis is not required.

Clinical features and treatment efficacy for IgG4-related thyroiditis

PURPOSE

This study aimed to clarify the clinical features of and evaluate the treatment efficacy for IgG4-related thyroiditis.

METHODS

Fourteen IgG4-related thyroiditis patients and 42 randomly matched IgG4-related disease (IgG4-RD) patients without thyroiditis in a prospective cohort at the Peking Union Medical College Hospital (PUMCH) were enrolled from 2011 to 2019. Patient demographics, clinical characteristics, laboratory parameters and treatment efficacy were analysed.

RESULTS

The prevalence of IgG4-related thyroiditis in our cohort was 2.0%. The average patient age was 42.8 ± 14.9 years, and the male: female ratio was 1:1. Goiter (14, 100.0%), hard thyroid (14, 100.0%) and neck compression (5, 35.7%) were the most prevalent onset symptoms observed. IgG4-related thyroiditis was characterized by asymmetric diffuse thyroid enlargement on ultrasound. Thirteen (92.9%) patients had hypothyroidism, and all patients had significantly elevated circulating thyroid antibodies. Compared with patients without thyroiditis, patients with IgG4-related thyroiditis had less submandibular gland involvement and lacrimal gland involvement and lower serum IgG4 and T-IgE levels (P = 0.019, P = 0.022, P = 0.004, and P = 0.006, respectively) and more single-organ involvement (P = 0.011). After treatment, the symptoms were relieved, while the size of the thyroid gland did not change significantly, and levothyroxine as a supplemental therapy was still needed.

CONCLUSIONS

IgG4-related thyroiditis is a distinct subtype of IgG4-RD characterized by positive circulating thyroid antibodies and a high rate of hypothyroidism. Although compression symptoms could be relieved with treatment, the thyroid size did not change significantly, and the damage to thyroid function was often irreversible.

[Clinical practice guidelines for acute and chronic thyroiditis (excluding autoimmune thyroiditis)]

Острые и хронические заболевания щитовидной железы занимают второе место по выявляемости после сахарного диабета. Всемирная организация здравоохранения отмечает ежегодную тенденцию к увеличению числа заболеваний щитовидной железы. В настоящих клинических рекомендациях будут рассмотрены вопросы этиологии, клинического течения, диагностики и лечения острых и хронических (за исключением аутоиммунного) воспалительных заболеваний щитовидной железы.Клинические рекомендации — это основной рабочий инструмент практикующего врача, как специалиста, так и врача узкой практики. Лаконичность, структурированность сведений об определенной нозологии, методов ее диагностики и лечения, базирующихся на принципах доказательной медицины, позволяют в короткий срок дать тот или иной ответ на интересующий вопрос специалисту, добиваться максимальной эффективности и персонализации лечения.Клинические рекомендации составлены профессиональным сообществом узких специалистов, одобрены экспертным советом Министерства здравоохранения РФ. Представленные рекомендации содержат максимально полную информацию, которая требуется на этапе диагностики острых и хронических тиреоидитов, этапе выбора тактики ведения пациентов с тиреоидитом, а также на этапе лечения пациента.Рабочая группа представляет этот проект в профессиональном журнале, посвященном актуальным проблемам эндокринологии, с целью повышения качества оказываемой медицинской помощи, повышения эффективности лечения острых и хронических тиреоидитов путем ознакомления с полным тестом клинических рекомендаций по острым и хроническим тиреоидитам (исключая аутоиммунный тиреоидит) максимально возможного количества специалистов в области не только эндокринологии, но и медицины общей (семейной) практики.

Proposal of diagnostic criteria for IgG4-related thyroid disease

Patients with IgG4-related disease (IgG4-RD) are diagnosed in Japan by comprehensive or organ-specific diagnostic criteria. To date, organ-specific criteria have been established for several organs, but not for the thyroid. We attempted to establish diagnostic criteria for IgG4-related thyroid disease (IgG4-RTD) based on IgG4-RD research by The Research Program on Intractable Diseases from the Ministry of Health, Labour and Welfare of Japan. These criteria have been publicly reported to members of both the Japan Endocrine Society and the Japan Thyroid Association. Thyroid diseases associated with IgG4 include Hashimoto's thyroiditis, Graves' disease and Riedel's thyroiditis. As a comprehensive definition that includes both systematic and organ-specific forms, we use the broad term 'IgG4-related thyroid disease'. Diagnostic criteria for IgG4-RTD comprise the following five items: I) enlargement of the thyroid, II) hypoechoic lesions in the thyroid by ultrasonography, III) elevated serum IgG4 levels, IV) histopathological findings in the thyroid lesion (IgG4⁺ plasma cells >20/HPF and IgG4⁺/IgG⁺ plasma cell ratio >30%) and V) involvement of other organs. "Definitive" diagnosis of IgG4-RTD is made when I, II, III and IV are all fulfilled, while "probable" diagnosis of IgG4-RTD is when I, II, and IV or V are fulfilled. Patients who fulfill I, II and III criteria are considered as "possible" IgG4-RTD. We believe that the proposed diagnostic criteria contribute to more accurate diagnosis of IgG4-RTD as well as exclusion of mimicry. Furthermore, they may lead to better understanding of the clinical implications and underlying pathogenesis of IgG4-RTD.

IgG4 thyroiditis in the Asian population

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibro-inflammatory condition that often causes the formation of tumefactive lesions. The discovery of IgG4-RD linked many well-known isolated conditions as a distinct multi-organ disease, and started an era of promoting investigation and treatment in relevant fields. In the thyroid gland, a subcategory of Hashimoto thyroiditis (HT) with IgG4-rich inflammation was first discovered and named IgG4 thyroiditis by our group. This subtype of HT presents with rapidly progressive clinical manifestations and destructive histopathological features underlying thyroid dysfunction, which are significantly different from the common type of HT. Moreover, other IgG4-rich thyroid conditions in patients with Graves' disease and systemic IgG4-RD have been described. These observations are most frequently reported in the Asian population for unknown reasons. Although recent studies demonstrated that IgG4 thyroiditis is a specific entity independent from IgG4-RD, recognition of this unique subset of thyroid disease has yielded important insights into understanding its pathogenesis and the development of novel therapeutic approaches.

Riedel Thyroiditis

CONTEXT

Riedel thyroiditis (RT) is a rare inflammatory autoimmune disease that is often a clinically diagnostic dilemma because of its insidious presentation and nonspecific symptoms.

OBJECTIVE

The aim of the present systematic review and meta-analysis is to clarify the presentation, management, and outcomes of RT.

STUDY SELECTION

A systematic search of PubMed/MEDLINE and Web of Science was conducted to identify relevant reports published up to September 2019.

DATA EXTRACTION

First author, country, patient sex, ethnicity, presentation, biochemical status, duration of symptoms, histology, treatment, follow-up duration, and short- and long-term outcomes.

DATA SYNTHESIS

Data from 212 RT patients were retrieved. The mean age was 47 years with a predominantly female population (81%). Neck swelling (89%), dyspnea (50%), and neck pain (41%) were the most common presenting symptoms. Inflammatory markers were elevated in 70% to 97% and thyroid antibody positivity was present in less than 50%. Up to 82% underwent surgical intervention, with the most common being total thyroidectomy in 34% of individuals. Glucocorticoids were used in 70% of individuals with median duration 3 months. Prognosis was reasonable with 90% having resolution or improvement of symptoms.

CONCLUSIONS

This analysis is the largest and most comprehensive to date of RT and provides clinicians with vital information on the common presentation features that may alert to the diagnosis and highlight management options.

IgG4-positive plasma cells in Hashimoto thyroiditis: IgG4-related disease or inflammation-related IgG4-positivity?

Despite the interest of researchers in IgG4-related disease (IgG4-RD), many questions still remain unanswered regarding the thyroid gland. We aimed to clarify the relationship between IgG4-positive plasma cells and the histopathological pattern in the Hashimoto thyroiditis (HT) in a Finnish series. HT specimens (n = 280) were retrieved from the Department of Pathology, Fimlab Laboratories. After re-evaluation, 82 (29%) cases (72 females and 10 males, 52 ± 17 years) with significant fibrosis were selected. CD38, IgG and IgG4 positivity in plasma cells was evaluated by immunohistochemistry. Adjusted IgG4-positive plasma cells per HPF > 20 and IgG4- to IgG-positive plasma cell ratio > 30% were adopted as threshold criteria and related to other morphological features. IgG4-positive HT group included 13 cases (15% from fibrotic HT, 4.6% from all HT, 50 ± 15 years, 11 females) with adjusted HPF count 30 ± 5 (23-40) IgG4-positive cells. IgG4-positivity significantly correlated with the presence of lobulation, oncocytic metaplasia and certain type of fibrosis, fibrosis spread outside the gland, lymphocytes/plasma cells epithelial penetration, the predominance of microfollicles and follicular atrophy in the present study. Despite the persisting uncertainty whether HT is IgG4-RD, HT with IgG4-positive plasma cells is histopathologically distinct entity with some geographic variability.

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.

Potential roles of extracellular vesicles in the pathophysiology, diagnosis, and treatment of autoimmune diseases

Since extracellular vesicles (EVs) were discovered in 1983 in sheep reticulocytes samples, they have gradually attracted scientific attention and become a topic of great interest in the life sciences field. EVs are small membrane particles, released by virtually every cell that carries a variety of functional molecules. Their main function is to deliver messages to the surrounding area in both physiological and pathological conditions. Initially, they were thought to be either cell debris, signs of cell death, or unspecific structures. However, accumulating evidence support a theory that EVs are a universal mechanism of communication. Thanks to their biological characteristics and functions, EVs are likely to represent a promising strategy for obtaining pathogen information, identifying therapeutic targets and selecting specific biomarkers for a variety of diseases, such as autoimmune diseases.

In this review, we provide a brief overview of recent progress in the study of the biology and functions of EVs. We also discuss their roles in diagnosis and therapy, with particular emphasis on autoimmune diseases.

A Literature Review of Painful Hashimoto Thyroiditis: 70 Published Cases in the Past 70 Years

Painful Hashimoto thyroiditis (pHT) is a rare diagnosis, and optimal treatment remains unclear. To better characterize pHT, PubMed, Embase, Scopus, and Web of Science indexes were searched for case reports or case series reporting pHT, published between 1951 and February 2019. Seventy cases reported in 24 publications were identified. Female predominance (91.4%) and a median age of 39.00 years (interquartile range, 32.50-49.75 years) were observed. Among reported cases, 50.8% had known thyroid disease (including Hashimoto thyroiditis, Graves disease, and seronegative goiters), 83.3% had positive antithyroid peroxidase antibodies, and 71.2% had antithyroglobulin antibodies. Most cases did not have preceding upper respiratory tract symptoms or leukocytosis. Ultrasound features were consistent with Hashimoto thyroiditis. Thyroid function at initial presentation was hypothyroid (35.9%), euthyroid (28.1%), or thyrotoxic (35.9%). Cases evolved into hypothyroidism (55.3%) and euthyroidism (44.7%), whereas none became hyperthyroid after medical treatment. Thyroid size usually decreased after medical treatment. Most cases were empirically treated as subacute thyroiditis with corticosteroids, levothyroxine, or nonsteroidal anti-inflammatory drugs. However, no therapy provided sustained pain resolution. In subgroup analysis, low-dose oral prednisone (<25 mg/d) and intrathyroidal corticosteroid injection showed more favorable outcomes. Total thyroidectomy yielded 100% sustained pain resolution. Diagnosis of pHT is based on clinical evidence of Hashimoto thyroiditis and recurrent thyroid pain after medical treatment. The reference standard of diagnosis is pathology. Total thyroidectomy or intrathyroidal glucocorticoid injection should be considered if low-dose oral prednisone fails to achieve pain control.

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.

IgG4-related disease in endocrine practice

IgG4-related disease is a set of symptoms resulting from a chronic, usually multiple organ inflammatory condition which affects various organs. It consists of lymphoplasmacytic infiltrations with attendant fibrosis and deep vein thrombosis. Frequently observed tissue lesions are accompanied by elevated IgG4 levels in serum. The etiopathogenesis of the lesions is of multifactor character and the clinical manifestation of the disease is highly diverse. The diagnostic process is based on the patient's medical history, clinical examination and additional tests, including a histopathological examination of the infected organ's tissues. Almost forty different locations of the disease have been reported, including disorders of the endocrine system. IgG4-related endocrinopathies are quite rare. However, it is likely that the diagnosis is under-reported due to lack of awareness of this clinical entity. Despite increasing interest in the subject, there are not enough reliable studies evaluating the link between IgG4-RD and endocrine disorders.

Hashimoto's thyroiditis with elevated serum IgG4 concentrations is not equivalent to IgG4 Hashimoto's thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT) with serum IgG4 concentrations greater than 135 mg/dL can be diagnosed as elevated serum IgG4 HT. HT can also be classified into IgG4 HT and non-IgG4 HT based on an immunohistochemistry analysis of IgG4. The aim of our study was to determine the relationship between elevated serum IgG4 HT and IgG4 HT.

METHOD

Both thyroid tissues and serum samples stored before pathological examination from 93 patients with HT were collected. The serum levels of IgG, IgG4, TgAb IgG, TgAb IgG4, TPOAb IgG and TPOAb IgG4 were measured by ELISAs. The expression levels of IgG4, IgG and TGF-β1 in thyroid tissues were detected by immunohistochemistry.

RESULTS

Patients with HT were divided into two groups: elevated serum IgG4 HT (n = 12) and nonelevated serum IgG4 HT (n = 81). Hypothyroidism was found in 5 of 12 cases (41.7%) in the elevated serum IgG4 HT group and 10 of 81 cases (12.3%) in the nonelevated serum IgG4 HT group (P = .023). Serologically, there were no significant differences in the levels of TgAb IgG, TPOAb IgG, TgAb IgG4 and TPOAb IgG4 between the two groups, and the expression of TGF-β1 in thyroid tissues was not significantly different between the groups. Most importantly, the frequency of patients who satisfied the criteria for IgG4 HT diagnosis was comparable (25% vs 20.9%, P = .756).

CONCLUSIONS

The measurement of serum IgG4 allows the identification of patients with HT closely associated with hypothyroidism. However, our study demonstrated that elevated serum IgG4 HT is not equivalent to IgG4 HT.

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.

Hypothyroidism in patients with autoimmune pancreatitis

AIM

To examine thyroid function and clinical features of hypothyroidism in autoimmune pancreatitis (AIP) patients.

METHODS

We examined thyroid function in 77 patients with type 1 AIP (50 males, 27 females; median age 68 years, range 33-85) diagnosed according to the Japanese diagnostic criteria for AIP 2011. We compared clinical and serological findings between patients with and without various categories of hypothyroidism. The change in hypothyroidism after steroid therapy was also examined.

RESULTS

Eight patients (10%) had hypothyroidism of 6 patients had subclinical hypothyroidism with a normal serum free thyroxine (FT4) and high thyroid stimulating hormone (TSH) level, and 2 patients had central hypothyroidism with low serum free triiodothyronine (FT3), FT4 and TSH levels. A significant goiter of the thyroid was not observed in any patient. There were no significant differences in age; male to female ratio; serum concentrations of IgG and IgG4-related disease (IgG4-RD); presence of anti-thyroglobulin antibody, antinuclear antigen or rheumatoid factor; or presence of extrapancreatic lesions between the 6 patients with subclinical hypothyroidism and patients with euthyroidism. After steroid therapy, both subclinical and central hypothyroidism improved with improvement of the AIP.

CONCLUSION

Hypothyroidism was observed in 8 (10%) of 77 AIP patients and was subclinical in 6 patients and central in 2 patients. Further studies are necessary to clarify whether this subclinical hypothyroidism is another manifestation of IgG4-RD.

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.

Warthin-like papillary thyroid carcinoma with immunoglobulin G4-positive plasma cells possibly related to Hashimoto's thyroiditis

Hashimoto's thyroiditis with heavy lymphoplasmacytic infiltration is a common comorbidity of immunoglobulin G4 (IgG4)-related thyroiditis and Warthin-like papillary thyroid carcinoma (WL-PTC). We hypothesized that WL-PTC may have a strong association with IgG4-related thyroiditis. To validate this hypothesis, we clinically and immunohistochemically studied 17 WL-PTC cases. Fourteen patients (82.4%) had anti-thyroglobulin antibody and were confirmed to have Hashimoto's thyroiditis through microscopic analysis. Among them, five (29.4%) had disease consistent with IgG4-related thyroiditis but did not exhibit a "storiform" pattern or obliterative phlebitis. IgG4-related diseases were not found in other organs. No cases with serum IgG4 level of >135 mg/dL were noted. A total of 94.1% of WL-PTC cases had IgG4-positive plasma cells (⁺PCs) in the stroma, and cases with rich IgG4⁺PCs were more frequently associated with Hashimoto's thyroiditis than those with poor IgG4⁺PCs. In this study, all three cases without Hashimoto's thyroiditis had poor IgG4⁺PCs, and one of them did not exhibit IgG4⁺PCs in the stroma of WL-PTC and Hashimoto's thyroiditis. Nodal metastatic lesions were seen in eight cases, all of which were not WL-PTC. As such, we should consider that the Hashimoto's disease with rich IgG4⁺PCs seen in our cases is representative of non-IgG4-related disease and not IgG4-related disease involving multiple organs. This study is the first to demonstrate the presence of IgG4⁺PCs in the stroma of WL-PTC. We concluded that the appearance of IgG4⁺PCs in the stroma of WL-PTC may be related to Hashimoto's thyroiditis with rich IgG4⁺PC.

Case report: IgG4-related mass-forming thyroiditis accompanied by regional lymphadenopathy

Background

It has been recently accepted that IgG4-related thyroiditis is comparable to the Hashimoto and Riedel thyroiditis and Graves disease which are rich in IgG4-secreting plasma cells. Many physicians believe that in IgG4-related thyroiditis, the thyroid is entirely enlarged and diffusely affected, which is similar to conventional thyroiditis, but rarely ever accompanied by pseudoneoplastic mass formation as in IgG4-related disease in the other organs. This report introduces another pattern of IgG4-related thyroiditis as mass-forming thyroiditis and presents the occurrence of IgG4-related regional lymphadenopathy as an unusual accompanying symptom.

Case presentation

A 66-year-old woman presented with an approximately 2.5-cm mass in the right thyroidal lobe and regional lymph node swelling, which were preoperatively misinterpreted as thyroidal carcinoma. After lobectomy, histological examination was performed, revealing that the mass showed dense stromal fibrosis, lymphoplasmacytic infiltration, and effacement of thyroid follicles, while the background thyroidal tissue seemed to mimic lymphocytic thyroiditis without fibrosis. Immunohistochemistry revealed predominance of IgG4-secreting plasma cells among infiltrating lymphocytes independent of mass lesion or background tissue. In addition, the regional Delphian and paratracheal lymph nodes were swollen, histologically showing numerous IgG4-secreting plasma cell infiltrations in the interfollicular zone.

Conclusions

IgG4-related mass-forming thyroiditis, which may be an extremely rare but recognizable pattern of IgG4-related thyroiditis, may be distinguishable from Hashimoto and Riedel thyroiditis, Graves disease, and thyroidal carcinoma. In addition, the regional IgG4-related lymphadenopathy, also possibly misdiagnosed as metastatic thyroidal carcinoma, may be a newly recognized manifestation of IgG4-related thyroiditis.

A study of serum IgG4 levels in the clinical metamorphosis of autoimmune thyroid disease

Background

Measurement of serum IgG4 had been suggested to distinguish the unique subtypes of autoimmune thyroid disease (AITD) which demonstrated patterns of fluctuating between hyperthyroidism and hypothyroidism. However, the clinical utility of serum IgG4 measurement is inconclusive due to few studies having addressed these unusual patients compared with the specificity of serum IgG4 in healthy patients.

Aim

To investigate whether elevated serum IgG4 levels could be used as a marker to identify fluctuating AITD patients.

Materials and Methods

20 AITD patients who evolved from hyperthyroid Graves’ disease to spontaneous hypothyroidism or vice versa were compared with 40 healthy subjects, 40 patients with hyperthyroid Graves’ disease (GD) and 40 patients with subclinical or overt hypothyroid Hashimoto’s thyroiditis (HT). Serum levels of total IgG and IgG4 were measured and the proportion of elevated serum IgG4 levels (defined by serum IgG4 levels ≥ 135 mg/dL) was compared with control patients.

Results

A series of 20 Thai patients with clinical evolution of AITD was analyzed with a median follow-up at 92 months (range 3–380 months). Elevated serum IgG4 levels were not found in fluctuating AITD patients but were found in 5% of the control GD patients, 2.5% of the control HT, and 2.5% of healthy subjects which were not statistically significant between each group.

Conclusion

Our results contrasted with those of previous studies from Japan which reported elevated serum IgG4 as a marker to identify subset of AITD patients. At present, the clinical utility of serum IgG4 measurements in AITD is inconclusive and requires further investigation.

IgG4-Related Hashimoto's Thyroiditis of the Thyroid Gland

Immunoglobulin (Ig) G4-related Hashimoto's thyroiditis is a newly discovered subtype of Hashimoto's thyroiditis and characterized by thyroid inflammation and marked fibrosis. IgG4-related Hashimoto's thyroiditis is very rare and there has been relatively little information available to date. A 46-year-old woman with a past history of thyroid dysfunction visited our outpatient clinic for severe anterior neck swelling. She complained of swallowing discomfort and pain due to severe goiter and was successfully treated with total thyroidectomy. Immunohistochemistry showed thyroid invasion by IgG4-positive cells and an IgG4/IgG ratio over 40%. The patient was diagnosed with IgG4-related Hashimoto's thyroiditis. We report a very rare case of IgG4-related Hashimoto's thyroiditis with severe goiter. A more comprehensive understanding of the IgG4-related Hashimoto's thyroiditis may help physicians to allow proper diagnosis and treatment of patients with severe goiter.

Serum immunoglobulin G4 levels and Graves' disease phenotype

PURPOSE

We investigated, at diagnosis, the relationship between serum immunoglobulin G4 levels and the main characteristics of Graves' disease: hyperthyroidism severity, goiter size, presence of active Graves' ophthalmopathy, antithyroid antibodies status, and titer.

METHODS

This prospective study included 80 newly diagnosed Graves' disease patients. The main parameters measured at diagnosis: thyroid-stimulating hormone, free thyroxine, free triiodothyronine, total triiodothyronine, thyroglobulin, antithyroid peroxidase antibodies, anti-thyroglobulin antibodies, thyroid-stimulating hormone receptor antibodies, immunoglobulin G4.

RESULTS

In Graves' disease patients, serum immunoglobulin G4 levels were higher than in general population (p = 0.028) and higher in men compared to women (p = 0.002). Only one female patient with intense hypoechoic goiter, high anti-thyroglobulin antibody, and antithyroid peroxidase antibody titers had an elevated serum immunoglobulin G4 level at diagnosis. Patients with immunoglobulin G4 levels above the 75th percentile (>237.52 mg/dl, N = 20) were younger at Graves' ophthalmopathy onset (p < 0.001), had higher antithyroid peroxidase antibody (p = 0.01), and anti-thyroglobulin antibody levels (p = 0.006) and required shorter duration of the first methimazole treatment cycle (p = 0.041) than patients with immunoglobulin G4 below the 75th percentile. At diagnosis, patients with immunoglobulin G4 levels above the 90th percentile (>286.28 mg/dl, N = 8) had lower total triiodothyronine values (p = 0.001) than patients with IgG below the 90th percentile. No significant correlations were found between smoking status (p = 0.58), goiter size (p = 0.50), the presence of ophthalmopathy (p = 0.42) or thyroid-stimulating hormone receptor antibody titers (p = 0.45) and the mean value of immunoglobulin G4 levels at diagnosis.

CONCLUSIONS

Our data suggest that Graves' disease patients with elevated immunoglobulin G4 levels at diagnosis have a phenotype characterized by higher anti-thyroglobulin antibody and antithyroid peroxidase antibody titers, less severe T3 hyperthyroidism, younger age at ophthalmopathy onset and require a shorter duration of the first methimazole treatment cycle.

Clinical Features of Patients with Basedow's Disease and High Serum IgG4 Levels

Objective IgG4-related disease is a recently characterized condition presenting with high blood IgG4 levels, swelling of organs, and hypertrophic lesions. This disease is associated with thyroid disease, Hashimoto's disease, and Riedel's thyroiditis. However, there is little information on the association between IgG4-related disease and Basedow's disease. We herein defined the clinical features of patients with Basedow's disease and high IgG4 levels. Methods We compared two groups of patients with Basedow's disease (n=72) who had either normal IgG4 levels (<135 mg/dL; n=67) or high IgG4 levels (≥135 mg/dL; n=5 [6.9%], mean IgG4: 206±116 mg/dL, IgG4/IgG ratio: 10.6%±3.3%). Patients Seventy-two newly diagnosed, untreated patients with Basedow's disease. Results Compared to the normal IgG4 group, patients in the high IgG4 group were predominantly male and showed a significantly higher thyroid low-echo score (1.8±0.4 vs. 1.2±0.5) and eosinophil count (363±354/mm² vs. 136±122/mm²). Five patients had high IgG4 levels: one had a pancreatic lesion, and four had thyroid lesions. Conclusion Patients with Basedow's disease and high IgG4 levels may represent a new subtype of Basedow's disease. Further studies with larger sample sizes are needed.

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.

Clinical Update in Aspects of the Management of Autoimmune Thyroid Diseases

Aspects of autoimmune thyroid disease updated in this review include: immunoglobulin G4 (IgG4)-related thyroid disease (Riedel's thyroiditis, fibrosing variant of Hashimoto's thyroiditis, IgG4-related Hashimoto's thyroiditis, and Graves' disease with elevated IgG4 levels); recent epidemiological studies from China and Denmark indicating that excess iodine increases the incidence of Hashimoto's thyroiditis and hypothyroidism; immunomodulatory agents (ipilimumab, pembrolizumab, nivolumab) activate immune response by inhibiting T-cell surface receptors which down-regulate immune response, i.e., cytotoxic T-lymphocyte antigen 4 and programmed cell death protein 1 pathways; alemtuzumab is a humanised monoclonal antibody to CD52 which causes immune depletion and thyroid autoimmune disease especially Graves' hyperthyroidism; small molecule ligand (SML) agonists which activate receptors, SML neutral antagonists, which inhibit receptor activation by agonists, and SML inverse agonists which inhibit receptor activation by agonists and inhibit constitutive agonist independent signaling have been identified. SML antagonism of thyroid-stimulating hormone-receptor stimulatory antibody could treat Graves' hyperthyroidism and Graves' ophthalmopathy; and thyroxine treatment of subclinical hypothyroidism can produce iatrogenic subclinical hyperthyroidism with the risk of atrial fibrillation and osteoporosis. The increased risk of harm from subclinical hyperthyroidism may be stronger than the potential benefit from treatment of subclinical hypothyroidism.

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.

Association of CTLA-4 gene polymorphisms -318C/T and +49A/G and Hashimoto's thyroidits in Zahedan, Iran

Hashimoto's thyroiditis (HT) is a chronic inflammation of the thyroid gland and is known as the most common autoimmune disease. Development of autoimmune destruction of thyroid cells is a multi-step process involving convergence of genetic and environmental factors. Cytotoxic T-lymphocyte antigen-4 (CTLA-4) has an important role in homeostasis and negative regulation of immune responses, and is therefore considered to be a key element in the development of autoimmune diseases. The present study evaluated the association of the CTLA-4 gene polymorphisms 318C/T (rs5742909) and +49A/G (rs231775) with HT in an Iranian population (including 82 patients with HT and 104 healthy controls who were referred for routine premarital blood screenings). Genotyping was performed using the tetra-primer amplification refractory mutation system polymerase chain reaction technique. No significant differences were observed in genotype and allele frequencies in the single nucleotide polymorphisms (SNPs) between cases and controls. In the cases as well as in the controls, the TT genotype in the -318C/T polymorphism was absent and the predominant genotype was CC, while the predominant genotype for the +49A/G SNP was AA. As only few studies in this field have assessed Iranian and even Middle Eastern populations, additional studies with a higher number of samples are recommended to further assess the impact of -318C/T (rs5742909) and +49A/G (rs231775) polymorphisms of CTLA-4 on HT.

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.

Current Concept of IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a fibroinflammatory disease of unknown etiology, which is characterized by a tendency to form tumefactive lesions, increased serum levels of IgG4, and massive infiltration of IgG4-positive plasma cells with storiform fibrosis and/or obliterative phlebitis. Patients with IgG4-RD have frequently multiorgan involvements such as the pancreas, biliary tree, salivary glands, periorbital tissues, kidneys, lungs, lymph nodes, and retroperitoneum. IgG4-RD mainly affects middle-aged to elderly men except for involvement in lachrymal and salivary glands, so-called Mikulicz's disease. The clinical manifestations of IgG4-RD depend on individually involved organs and respond well to steroid, but the prognosis still remains unclear. Some patients develop serious complications such as obstructive jaundice due to hepatic, gallbladder, or pancreatic lesions; hydronephrosis due to retroperitoneal fibrosis; or respiratory symptoms due to pulmonary lesions. Nomenclatures of individual organ manifestation of IgG4-RD have been internationally consented.

IgG4-positive extranodal marginal zone lymphoma arising in Hashimoto's thyroiditis: clinicopathological and cytogenetic features of a hitherto undescribed condition

AIMS

Hashimoto's thyroiditis was recently divided into IgG4-plasma cell-rich and IgG4-plasma cell-poor subtypes. The former, also known as IgG4 thyroiditis, is associated with clinical, serological, sonographic and morphological features that are distinctive from those of the non-IgG4 subgroup. We describe an interesting case of IgG4-positive mucosa-associated lymphoid tissue (MALT) lymphoma arising in a background of IgG4 thyroiditis.

METHODS AND RESULTS

The thyroid gland showed typical features of IgG4 thyroiditis, including characteristic patterns of fibrosis. A dense lymphoplasmacytic infiltrate diffusely involved the entire gland without formation of a destructive tumour mass. Lymphoepithelial lesions were prominent. There were abundant IgG4-positive plasma cells, with the IgG4/IgG ratio exceeding 40%. The IgG4-positive plasma cells were monotypic for kappa light chain, and there was monoclonal IGH rearrangement. Fluorescence in-situ hybridization revealed IGH translocation without translocation of MALT1, bcl-10, or FOXP1.

CONCLUSIONS

This represents the first case of IgG4-producing MALT lymphoma associated with IgG4 thyroiditis. IGH translocation with an unknown partner gene was identified. We suggest the performance of serum and immunohistochemical investigations for IgG and IgG4 in all cases of Hashimoto's thyroiditis to diagnose IgG4 thyroiditis. In addition, clonality assays and light chain studies are useful to exclude a low-grade lymphoma arising in this context.

The importance of IgG4 in the predictive model of thyroiditis

Immunoglobulin (Ig)G4-related sclerosing disease (IgG4-RSD) is a new disease entity first proposed with regard to autoimmune pancreatitis. A 67-year-old male patient was examined because of weight loss and an abdominal pain. Based on the clinical characteristics, laboratory parameters and ultrasound features, we identified the diagnosis of the IgG4-related systemic disease (IgG4-RSD), that was confirmed by the histopathological analysis after the biopsy of the head of pancreas. After confirmation, we started with the corticosteroid therapy with a good clinical, biochemical and morphological response. During the previous therapy, the disturbance of glucoregulation appeared, so we had to change the modality of treatment. We decided to add Azathioprine to the therapy in a dose of 150 mg/day. We achieved a stable phase of the disease with IgG 4.37 g/l and IgG4 0.179 g/l, and with no side effects from the therapy.

Graves' Disease Patients with Persistent Hyperthyroidism and Diffuse Lymphoplasmacytic Infiltration in the Thyroid Show No Histopathological Compatibility with IgG4-Related Disease

BACKGROUND

IgG4-related disease is a novel disease entity characterized by diffuse lymphoplasmacytic infiltration rich in IgG4-positive plasma cells and fibrosis into multiple organs. There is still controversy over whether some thyroid diseases are actually IgG4-related disease. The objective of this study was to elucidate the clinicopathological features of Graves' disease with diffuse lymphoplasmacytic infiltration in the thyroid.

PATIENTS AND METHODS

Among 1,484 Graves' disease patients who underwent thyroidectomy, we examined their histopathological findings including the degree of lymphoplasmacytic and fibrotic infiltration and levels of IgG4-positive plasma cells in the thyroid. Their clinical pictures were defined by laboratory and ultrasonographic evaluation.

RESULTS

A total of 11 patients (0.74%) showed diffuse lymphoplasmacytic infiltration in the stroma of the thyroid gland. Meanwhile, other patients showed variable lymphoid infiltration ranging from absent to focally dense but no aggregation of plasma cells in the thyroid gland. Based on the diagnostic criteria of IgG4-related disease, 5 of the 11 subjects had specifically increased levels of IgG4-positive plasma cells in the thyroid. Fibrotic infiltration was present in only 1 patient developing hypothyroidism after anti-thyroid drug treatment for 4 years, but not in the other 10 patients with persistent hyperthyroidism. Obliterative phlebitis was not identified in any of the 11 subjects. Thyroid ultrasound examination showed 1 patient developing hypothyroidism who had diffuse hypoechogenicity, but the other hyperthyroid patients had a coarse echo texture.

CONCLUSIONS

In our study, Graves' disease patients with persistent hyperthyroidism who had diffuse lymphoplasmacytic infiltration rich in IgG4-positive plasma cells in the thyroid showed no concomitant fibrosis or obliterative phlebitis.