Papillary Thyroid Cancer and Hashimoto's Thyroiditis: An Association Less Understood

An Autobiographical Case Report on Papillary Thyroid Carcinoma with Positive Antithyroid Antibodies: Coincidence or Correlated?

The relationship between autoimmunity and cancer has been a gray area, with many theories but no solid proof so far. Hashimoto's thyroiditis is an autoimmune disorder and a major cause of hypothyroidism, while papillary thyroid carcinoma is the most common thyroid malignancy generally found in patients younger than 45 years of age. The literature on the correlation between these two disorders is somewhat based on potentially biased histopathological examination from pre-operative fine needle aspiration and post-thyroidectomy samples. Although recent studies are evaluating a possible holistic molecular, hormonal, and histopathological foundation for this correlation, a clear causal relationship has not been established yet. This report illustrates the author's case presentation, treatment, and eventual outcome of the disease when she was diagnosed with papillary thyroid cancer at the age of 25 years, with positive antithyroid peroxidase and antithyroglobulin antibodies.

Ultrasound-based Nomogram for Predicting the Pathological Nodal Negativity of Unilateral Clinical N1a Papillary Thyroid Carcinoma in Adolescents and Young Adults

RATIONALE AND OBJECTIVES

To develop and validate a nomogram incorporating clinical and ultrasound (US) characteristics for predicting the pathological nodal negativity of unilateral clinically N1a (cN1a) papillary thyroid carcinoma (PTC) among adolescents and young adults.

MATERIALS AND METHODS

From December 2016 to August 2021, 278 patients aged ≤ 30 years from two medical centers were enrolled and randomly assigned to the training and validation cohorts at a ratio of 2:1. After performing univariate and multivariate analyses, a nomogram combining all independent predictive factors was constructed and applied to the validation cohort. The performance of the nomogram was evaluated using receiver operating characteristic curves, calibration curves, and decision curve analysis .

RESULTS

Multivariate logistic regression analysis showed that unilateral cN1a PTC in young patients with Hashimoto's thyroiditis, T1 stage, no intra-tumoral microcalcification, and tumors located in the upper third of the thyroid gland was more likely to be free of central lymph node metastases. The nomogram revealed good calibration and discrimination in both cohorts, with areas under the receiver operating characteristic curve of 0.764 (95% confidence interval [CI]: 0.684-0.843) and 0.728 (95% CI: 0.602-0.853) in the training and validation cohorts, respectively. The clinical application of the nomogram was further confirmed using decision curve analysis.

CONCLUSION

This US-based nomogram may assist the assessment of central cervical lymph nodes in young patients with unilateral cN1a PTC, enabling improved risk stratification and optimal treatment management in clinical practice.

Collision tumor of the thyroid - a challenge during the COVID-19 pandemic

Some of the patients with anaplastic thyroid carcinomas have a coexistent differentiated thyroid cancer, sustaining the hypothesis that this cancer may develop from more differentiated tumors. We describe a case with a collision tumor of the thyroid, defined as a neoplastic lesion composed of two distinct cell populations, with distinct borders. The patient presented during the COVID-19 pandemic with dysphonia, dyspnea, multinodular goiter and a painless, rapidly enlarging, left cervical swelling. She had been first time diagnosed with left nodular goiter in 2007, with an indication for surgery, which she declined. After partial excision of the left latero-cervical adenopathy, the pathological analysis showed massive lymph node metastasis from anaplastic thyroid cancer. A total thyroidectomy was done; the postoperative pathological exam identified a papillary thyroid microcarcinoma in the right lobe and an anaplastic thyroid cancer in the left lobe. Postoperatively, levothyroxine treatment was started and the patient was referred to radiotherapy. This case highlights the importance of urgent management of some cases with compressive multinodular goiter, even during the COVID-19 pandemic.

Is Hashimoto thyroiditis associated with increasing risk of thyroid malignancies? A systematic review and meta-analysis

Background and purpose

Hashimoto thyroiditis (HT) is the most common inflammatory autoimmune thyroid disease and also the most common cause of hypothyroidism in developed countries. There is evidence of the role of HT in developing thyroid cancers (TCs). This study investigated the association between HT and different types of TCs.

Methods

Results of a comprehensive search in three major databases, as well as hand searching, were screened in title/abstract and full-text stages and the relevant data were extracted from the studies that met the inclusion criteria. Risk of bias (RoB) was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools and the meta-analysis was conducted with Comprehensive Meta-Analysis software.

Results

Out of 4785 records, 50 studies were included in the systematic review, and 27 of them met the criteria for quantitative synthesis. The results indicated a significant role for HT in developing papillary TC (OR: 1.65; 95% CI: 1.04 to 2.61), medullary TC (OR: 2.70; 95% CI: 1.20 to 6.07) and lymphoma (OR:12.92; 95% CI: 2.15 to 77.63); but not anaplastic TC (OR: 1.92; 95% CI: 0.29 to 1.90) and follicular TC (OR: 0.73; 95% CI: 0.41 to 1.27). Also, this study found a significant association between HT and thyroid malignancies (OR: 1.36; 95% CI: 1.05 to 1.77).

Conclusion

Although we found a significant association between HT and some types of TCs, High RoB studies, high level of heterogeneity, and the limited number of well-designed prospective studies, suggested the need for more studies to reach more reliable evidence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13044-021-00117-x.

The Association of Histologically Proven Chronic Lymphocytic Thyroiditis with Clinicopathological Features, Lymph Node Metastasis, and Recurrence Rates of Differentiated Thyroid Cancer

The influence of chronic lymphocytic thyroiditis (CLT) on clinicopathological features and behavior of differentiated thyroid carcinoma (DTC) is still debated. In the present study, we aimed to evaluate the prognosis of DTC on the presence of CLT. A total of 649 total thyroidectomized patients (379 female, 270 male) with DTC, who had follow-up data for at least 36 months were included. Clinical, histopathological data, preoperative thyroid peroxidase antibody (TPO-ab), thyroglobulin antibody (Tg-ab), thyroid-stimulating hormone (TSH) levels, and presence of recurrent/persistent disease (R/PD) were evaluated retrospectively. Presence of CLT was defined by histopathology. Frequency of CLT was 32% (n = 208) among DTC patients. Mean tumor size (maximal diameter) was smaller in CLT group when compared to non-CLTs (p = 0.006). Capsular invasion, vascular invasion, tumor stage, risk groups, and R/PD were negatively associated with CLT (p < 0.01, p = 0.04, p = 0.03, p = 0.02, p < 0.01, respectively). Extrathyroidal extension was more frequent in non-CLT group when compared CLT (p = 0.052). Preoperative TSH level was positively associated with lymph node metastasis (LNM) and higher in patients with lateral LNM when compared to central LNM (p < 0.01). Central LNM, lateral LNM, stage 4 tumor, and intermediate- and high-risk tumor groups increased the risk of R/PH, 2.5-, 2.9-, 12.7-, 2.3-, and 4.2-fold, respectively. Presence of CLT was independently related with favorable outcomes, as the risk of R/PD was decreased by 0.49-fold. In conclusion, coexistence of CLT was negatively associated with tumor size, capsular invasion, vascular invasion, and tumor stage in DTC. Risk of R/PD was decreased by approximately half in patients with CLT.

The Fractal and GLCM Textural Parameters of Chromatin May Be Potential Biomarkers of Papillary Thyroid Carcinoma in Hashimoto's Thyroiditis Specimens

Occasionally, Hashimoto's thyroiditis (HT) and papillary thyroid carcinoma (PTC) share similar nuclear features. The current study aims to quantify the differences between the investigated specimens of HT-associated PTC versus the HT alone, to reduce the subjective experience of an observer, by the use of fractal parameters as well as gray-level co-occurrence matrix (GLCM) textural parameters. We have analyzed 250 segmented nuclei per group (nn = 25 per patient and np = 10 patients per group) using the ImageJ software (NIH, Bethesda, MD, USA) as well as an in-house written code for the GLCM analysis. The mean values of parameters were calculated for each patient. The results demonstrated that the malignant cells from the HT-associated PTC specimens showed lower chromatin fractal dimension (p = 0.0321) and higher lacunarity (p = 0.0038) compared with the corresponding cells from the HT specimens. Also, there was a statistically significant difference between the investigated specimens, in the contrast, correlation, angular second moment, and homogeneity, of the GLCM corresponding to the visual texture of follicular cell chromatin. The differences in chromatin fractal and GLCM parameters could be integrated with other diagnostic methods for the improved evaluation of distinctive features of the HT-associated PTC versus the HT in cytology and surgical pathology specimens.

Case Report: Familial Hypocalciuric Hypercalcaemia and Hashimoto's Thyroiditis

Introduction: Hypercalcaemia can be caused by many disorders. Primary hyperparathyroidism is the leading cause with parathyroidectomy being the definitive management. Familial hypocalciuric hypercalcaemia is a rarer cause in which resection of the parathyroid tissue does not result in normalized serum calcium.

Case presentation: We report the unusual case of a 53-year-old lady who presented with hypercalcaemia and elevated parathyroid hormone with a presumed diagnosis of primary hyperparathyroidism. She remained hypercalcaemic after parathyroidectomy and was later diagnosed with familial hypocalciuric hypercalcaemia. During the first operation, a lymph node was also removed, and the histopathology report suggested a metastasis of follicular variant papillary thyroid carcinoma (FVPTC). After multi-disciplinary team (MDT) discussion, the patient underwent a second exploration where total thyroidectomy and removal of the other parathyroid glands were performed. Hypercalcaemia completely resolved on surgical resection of the thyroid and parathyroid tissue, however histopathology revealed normal parathyroid glands and florid Hashimoto's thyroiditis. The initial diagnosis of FVPTC in the lymph node was revisited and the final histopathology report suggested an accessory thyroid nodule with florid Hashimoto's thyroiditis mimicking a lymph node.

Conclusion: Our case demonstrates the diagnostic dilemma in hypercalcaemia that may lead a patient to undergo unnecessary invasive procedures; the misdiagnosis of FVPTC after the first operation resulted in a second more extensive procedure. Patients with no clear surgical target and urine CCCR in the gray/non-diagnostic area should be routinely offered genetic testing despite negative family history.

Ectopic Cervical Thyroid Tissue Affected by Fibrosing Hashimoto's Thyroiditis Mimicking Multifocal Metastatic Papillary Thyroid Carcinoma-A Hard Lesson Learnt from an Unusual Case

We describe a case of ectopic cervical thyroid tissue which was involved by fibrosing Hashimoto's thyroiditis and which mimicked metastatic papillary thyroid carcinoma both on fine needle aspiration cytology and biopsy. The patient underwent total thyroidectomy which revealed fibrosing Hashimoto's thyroiditis, but no carcinoma. The entire thyroidectomy specimen was submitted for histopathological assessment. Even in the resected thyroidectomy specimen, there were cytological changes that were strongly reminiscent of papillary thyroid carcinoma. However, interpreted in the correct clinico-pathological context, these cytological alterations were deemed to be reactive secondary to the fibro-inflammatory process.

Thyroid cancer associated with Hashimoto thyroiditis: similarities and differences in an endemic area

BACKGROUND

Hashimoto thyroiditis (HT) is an autoimmune lymphocytic thyroiditis and is the most common form of thyroid inflammatory diseases. The association of HT with papillary thyroid carcinoma (PTC) has been described. PTC is the most common form of malignancy associated with HT. When papillary carcinoma develops on top of Hashimoto thyroiditis, the disease tends to be less aggressive and lymph node and extra-thyroidal invasion are infrequent.

RESULTS

We retrospectively examined the pathological features of our patients who were diagnosed with concomitant HT and thyroid cancer. In Egyptian patients, PTC was the main type of malignancy associated with HT (96.2%) and was often multifocal (46.2%). In contrast to the published literature, lymph node invasion and extra-thyroidal extension were as frequent in association with HT as in other cancer cohorts. We also observed the frequent occurrence of Hürthle cell metaplasia (23.1%) and the appreciable incidence of aggressive histological types of PTC (32%).

CONCLUSION

Thyroid carcinoma with HT may have some aggressive features in areas with endemic goiter background.

Indicators of multifocality in papillary thyroid carcinoma concurrent with Hashimoto's thyroiditis

Currently, no definitive diagnostic tool is available to distinguish unifocal and multifocal papillary thyroid carcinoma (PTC). This study aims to identify potential diagnostic markers of multifocal PTC. In 471 Hashimoto's thyroiditis (HT) patients, the significant difference was revealed in anti-thyroid peroxidase antibody (TPOAb) concentration, the cytokeratin-19 (CK-19) expression, the occurrence of the B-Raf proto-oncogene serine/threonine kinase (BRAF) mutations and the rearrangement in transformation (RET)/PTC. The patients' samples were assayed for the expression of CK-19, cyclooxygenase-2 (COX-2), galectin-3, and the protein human bone marrow endothelial cell marker-1 (HBME-1) using immunohistochemistry. The BRAF gene mutation was detected using a sequencer. Differences were examined using the Kruskal-Wallis test and the Chi-squared and Fisher's exact tests. The results showed that the elevated CK-19 expression, and the presence of BRAF mutations and RET/PTC rearrangements were indicators of multifocal PTC in HT, suggesting the need for total bilateral thyroidectomy. Among HT patients with TPOAb > 1300 IU/Ml, the occurrence of central lymph node metastasis is significantly higher in multi-focal PTC than single-focal PTC. Therefore, these markers may prove useful for discerning between uni- and multifocal PTC, thereby preventing unnecessary surgery in the treatment of unifocal PTC and promoting sufficient treatment of multifocal PTC.

Thyroid autoimmune diseases and thyroid tumors: Would EBV infection be the link?

The role of EBV in thyroid cancer development and the patient's outcome is still unclear. Using nested-PCR, Moghoofei et al. reported a high incidence of a virus in thyroid tumor samples, different from our results, obtained by quantitative real-time PCR and confirmed by in situ hybridization. Because lymphocytes are the main reservoir of the virus and tumor-infiltrating lymphocytes are commonly observed in thyroid cancer, it is important to distinguish follicular cells infection from lymphoid tissue infection. The association between autoimmune diseases and thyroid cancer raises the importance of continuing to investigate the role of ubiquitous pathogens in thyroid tumorigenesis.

Gender-specific correlation of intranodular chronic lymphocytic thyroiditis with thyroid nodule size, echogenicity, and histologically-verified cytological class of malignancy risk

No data are available on the cytologically and histologically demonstrated presence of intranodular chronic lymphocytic thyroiditis (ICLT) and on the ICLT relationship with thyroid nodule characteristics such as size, echotexture and nature (benign or malignant). We wished to fill this gap by analyzing data in a gender-specific fashion. We studied 408 thyroid nodules from 408 consecutive persons (325 females and 83 males). Nodules were isoechoic (n = 268) or hypoechoic (n = 140), ICLT +ve (n = 113 [27.7%]) or ICLT -ve (n = 295), cytologically low-risk (n = 197) or high-risk (n = 211), histologically benign (n = 263) or malignant (n = 145). ICLT prevailed in females (97/113) and in hypoechoic nodules (58/140 [41.4%] vs 55/268 [20.5%], P < 0.0001). Compared to males, females had (i) smaller nodules (18.5 ± 9.4 vs 23.3 ± 13.4 mm, P = 0.0002), a difference due to the isoechoic nodules (21.1 ± 9.8 vs 26.6 ± 14.1 mm, P = 0.0006), (ii) lower rates of high-risk nodules (161/325 [49.5%] vs 50/83 [60.2%], P = 0.082) and malignant nodules (110/325 [33.8%] vs 35/83 [42.2%] P = 0.16). ICLT +ve nodules were smaller than the ICLT -ve ones (15.4 ± 6.9 vs 20.9 ± 11.2 mm, P < 0.0001), a difference due to the isoechoic nodules (17.5 ± 6.5 vs 23.6 ± 11.7 mm, P = 0.0003). The smallest nodules were hypoechoic, cancerous and ICLT +ve nodules in males (9.5 ± 4.0 mm); the largest were isoechoic, cytologically risky and ICLT -ve in males (29.1 ± 13.2 mm). Compared to ICLT -ve nodules, malignancy prevailed in ICLT +ve nodules (55/113 [48.7%] vs 90/295 [30.5%], P = 0.0006), both in hypoechoic (37/58 [63.8%] vs 41/82 [50.0%]) and isoechoic nodules (18/55 [32.7%] vs 49/213 [23.0%]). ICLT +ve hypoechoic nodules of females and ICLT -ve hypoechoic nodules of males had the greatest rate of malignancy (67% both), while ICLT -ve isoechoic nodules of females had the lowest (19%). In conclusion, presence/absence of ICLT is associated with some sexually dimorphic characteristics of thyroid nodules. Adding the specification of ICLT positivity/negativity in cytological reports may help improving the risk of malignancy at least in some groups of thyroid nodules.

Clinical analysis of Hashimoto thyroiditis coexistent with papillary thyroid cancer in 1392 patients

Papillary thyroid carcinoma (PTC) is the most common malignant tumour of the thyroid. The effect of the concurrent presence of Hashimoto's thyroiditis (HT) and PTC is still under debate. The aim of this study is to investigate the influence of coexistent HT on prognostic outcomes and the association of coexistent HT with clinicopathological features. The demographic and clinicopathological data of 1,392 patients who underwent surgery in our hospital from 2007 to 2016 was collected and analysed. Among 1,392 PTC patients, the rate of HT was 25.6%. There were significant differences in the mean levels of thyroid stimulating hormone (3.27 vs. 2.41 μIU/L, p < 0.01), thyroperoxidase antibodies (110.31 vs. 131.2 U/ml, p < 0.01) and thyroglobulin antibodies (131.90 vs. 113.53 ng/ml, p < 0.01) between the two groups. PTC patients with HT had the following characteristics compared to patients without HT: smaller tumour size (p < 0.01), female predominance (p < 0.01) and higher rate of multifocality (p = 0.024). In addition, patients with HT had a significantly lower rate of lymph node metastasis (LNM) and advanced TNM stage than patients without HT (all p < 0.01). Multivariate analysis found that both age and multifocality were significantly associated with central LNM in HT patients (p < 0.01, p = 0.019, respectively). Extrathyroidal invasion and TSH level were also significant independent factors for lateral LNM in HT patients (p < 0.008, p = 0.04, respectively). HT is associated with a significantly higher risk of PTC. The coexistence of HT in PTC patients is associated with favourable clinical outcomes compared to PTC without HT. Total thyroidectomy and prophylactic central compartment lymphadenectomy should be a choice for PTC patients with HT.

Is only Thyroid Peroxidase Antibody Sufficient for Diagnosing Chronic Lymphocytic Thyroiditis?

Objectives:

Recently, only anti-thyroid peroxidase (anti-TPO) has been suggested as an autoantibody in the diagnosis of chronic lymphocytic thyroiditis (CLT). In contrast, anti-thyroglobulin (anti-Tg) positivity has also been reported to be important. To evaluate this relationship more clearly, we planned to retrospectively investigate the autoantibody levels of the patients who underwent thyroid surgery for various reasons and those with CLT in postoperative pathology.

Methods:

We evaluated 670 patients who underwent thyroid surgery (total/subtotal thyroidectomy) for various reasons at our hospital between January 2015 and March 2017. Patients with indications of Graves’ disease, toxic multinodular goiter, and all malignancies except for thyroid papillary carcinoma (TPC) were excluded. Eighty-nine patients whose pathology findings were compatible with CLT and preoperative thyroid autoantibodies were identified enrolled in to the study. Patients with absence and presence of thyroid antibodies were included in the seronegative CLT group and seropositive CLT group, respectively. In addition, patients were divided into thyroid papillary carcinoma (TPC) and benign groups.

Results:

According to the study criteria, 89 (83 females, six males) (mean age, 46.08±11.19 years) patients who had preoperatively identified autoantibodies were detected. Anti-TPO positivity was found in 47 (52.8%) cases, whereas anti-Tg positivity was found in 49 (55.1%). Only anti-TPO positivity was found in 18 (20.2%) cases, whereas only anti-Tg positivity was detected in 20 (22.5%). Twenty-two (24.7%) of the patients were seronegative. On comparing the seronegative and seropositive groups, seronegativity was more frequent in male patients (p=0.03). Thyroid-stimulating hormone was found to be significantly higher in the seropositive group (p=0.01). TPC was detected in 36 (40.4%) of all cases. No difference regarding age, thyroid function tests, and antibody levels was found between the benign and TPC groups.

Conclusion:

Although all of our cases were histopathologically diagnosed with CLT, serologically, 75.3% of thyroid autoimmunities could be shown when both antibodies were evaluated together. When only anti-TPO was considered, this rate decreased to 52.8%. Therefore, anti-Tg appears to be still important in showing autoimmunity. Prospective studies are needed to evaluate this relationship more clearly.

Intraoperative optical coherence tomography of the human thyroid: Feasibility for surgical assessment

Thyroid nodules assessed with ultrasound and fine-needle aspiration biopsy are diagnosed as "suspicious" or "indeterminate" in 15%-20% of the cases. Typically, total thyroidectomy is performed in such cases; however, only 25%-50% are found to be cancerous upon final histopathologic analysis. Here we demonstrate optical coherence tomography (OCT) imaging of the human thyroid as a potential intraoperative imaging tool for providing tissue assessment in real time during surgical procedures. Fresh excised tissue specimens from 28 patients undergoing thyroid surgery were imaged in the laboratory using a benchtop OCT system. Three-dimensional OCT images showed different microstructural features in normal, benign, and malignant thyroid tissues. A similar portable OCT system was then designed and constructed for use in the operating room, and intraoperative imaging of excised thyroid tissue from 6 patients was performed during the surgical procedure. The results demonstrate the potential of OCT to provide real-time imaging guidance during thyroid surgeries.

Impact of Hashimotoas thyroiditis on clinicopathologic features of papillary thyroid carcinoma associated with infiltration of tumor-infiltrating lymphocytes

The association between Hashimoto's thyroiditis (HT) and papillary thyroid carcinoma (PTC) has been a long and ongoing controversy. In the present study, a total number of 322 patients who underwent thyroidectomies were retrospectively studied, and the impact of HT with the incidence, clinicopathologic features, and presence of CD4+, CD8+ tumor-infiltrating lymphocytes (TILs) in PTC patients were analyzed. We further explored the correlation between CD4+, CD8+ TILs and clinicopathologic features in PTC patients with and without HT. The incidence of HT concurrent with PTC was 42.9%, which was significantly associated with a younger age (P=0.039) and the presence of hyperthyroid (P=0.010). The PTC patients coexistent with HT tended to be more female (P=0.001), with diffuse swelling of the thyroid (P<0.001), decreased TSH (P=0.004), and elevated anti-TgAb (P<0.001) and anti-TPOAb (P<0.001). The tumor size of PTC with HT was smaller (P=0.006) and exhibited more bilateral tumors (P<0.001) and less lymph node metastasis (P=0.016). Furthermore, CD4+ and CD8+ TILs in PTC with HT were significantly higher than without HT (both P<0.001). Both high CD4+ and CD8+ TILs were significantly associated with elevated TSH (P=0.019 and P=0.023, respectively), anti-TgAb (P=0.002 and P=0.001, respectively) and anti-TPOAb (P=0.001 and P=0.003, respectively), and the tumor size was smaller (P=0.017 and P=0.039, respectively) and with less lymph node metastasis (P=0.012 and P<0.001, respectively) in PTC with HT. Our study suggests that HT is significantly associated with PTC, which might be ascribed to infiltration of CD4+, CD8+ TILs.

Cytokine profiles in papillary thyroid carcinoma, with or without Hashimoto’s thyroiditis

The phenomenon that papillary thyroid carcinoma (PTC) is often accompanied by Hashimoto’s thyroiditis (HT) raised interest in further study of immune changes caused by thyroid autoimmunity. We aimed to characterize cytokine profiles in the peripheral blood of patients with PTC with or without HT, compared with nodular goiter (NG) and healthy control (HC) patients, in order to determine the autoimmunity-related differences among these groups. A total of 50 PTC patients were divided into two groups, according to whether or not concurrent HT existed. A total of 20 NG patients and 20 HC subjects were also included as controls. All PTC patients and NG patients who underwent surgical thyroidectomy and pathology examination were included. The serum levels of four cytokines, including interferon gamma (IFN-γ), interleukin (IL)-17, IL-10, and IL-35 were measured using AimPlex bead–based immunoassays. Peripheral IFN-γ and IL-35 increased significantly in PTC patients with concurrent HT. IL-10 and IL-35 increased significantly in three groups (PTC with or without HT and NG patients), while IFN-γ increased only in the two PTC groups. IL-17 was highest in the HC group, but significantly lower in the other three groups. IL-17, IL-10, and IL-35 may be involved in tumor onset and progression. Moreover, IFN-γ and IL-35 may play vital roles in the concurrence of PTC and HT, which could warrant further exploration.

[Inflammatory diseases of the thyroid gland]

This review article deals with the classification, clinical features and morphology of thyroiditis. These inflammatory diseases account for approximately 20 % of all thyroid diseases. The vast majority of cases of thyroiditis are of immunogenic origin while non-immunogenic thyroiditis (caused by pathogens or iatrogenic) is a rarity.

Association between Hashimoto's Thyroiditis and Thyroid Cancer in 64,628 Patients

Background

The incidence of thyroid cancer (TC) is increasing although explanatory causes are lacking. A link between cancer and inflammation is well documented but unclear for autoimmune thyroid diseases and TC. We aimed to systematically review the association between Hashimoto’s thyroiditis (HT) and papillary, follicular, medullary, anaplastic thyroid carcinoma, and thyroid lymphoma (TL).

Methods

PubMed, OVID Medline, Google Scholar, and the Cochrane Library were searched from 1955 to 2016. The inclusion criteria were age >18 years, ≥20 cases of HT or TC. We collectively examined the incidence of HT in TC and of TC in HT.

Results

We identified 36 studies (64,628 subjects) published between 1955 and 2016 from 13 countries. We found a relative risk (RR) of HT among papillary thyroid cancer (PTC) of 2.36 [95% confidence intervals (CIs) 1.55–3.29, p < 0.001], an RR of PTC among HT of 1.40 (95% CI 1.07–1.85, p = 0.016), and an RR of TL among HT of 9.74 (95% CI 3.93–24.13, p < 0.001).

Conclusion

We report an association between HT and PTC and between HT and TL. No association was found between HT and follicular, medullary, or anaplastic thyroid cancer.

Insulin Resistance: Any Role in the Changing Epidemiology of Thyroid Cancer?

In the past few decades, the incidence of thyroid cancer (TC), namely of its papillary hystotype (PTC), has shown a steady increase worldwide, which has been attributed at least in part to the increasing diagnosis of early stage tumors. However, some evidence suggests that environmental and lifestyle factors can also play a role. Among the potential risk factors involved in the changing epidemiology of TC, particular attention has been drawn to insulin-resistance and related metabolic disorders, such as obesity, type 2 diabetes, and metabolic syndrome, which have been also rapidly increasing worldwide due to widespread dietary and lifestyle changes. In accordance with this possibility, various epidemiological studies have indeed gathered substantial evidence that insulin resistance-related metabolic disorders might be associated with an increased TC risk either through hyperinsulinemia or by affecting other TC risk factors including iodine deficiency, elevated thyroid stimulating hormone, estrogen-dependent signaling, chronic autoimmune thyroiditis, and others. This review summarizes the current literature evaluating the relationship between metabolic disorders characterized by insulin resistance and the risk for TC as well as the possible underlying mechanisms. The potential implications of such association in TC prevention and therapy are discussed.