Thyroid nodules: pathogenesis, diagnosis and treatment

Development and evaluation of an original phantom model of ultrasonography-guided thyroid gland biopsy for the training of surgical residents and students

PURPOSES

Fine-needle aspiration cytology (FNAC) is a specific and important test used for the diagnosis of thyroid gland cancer. We developed a thyroid gland phantom using original manufacturing techniques and direct three-dimensional (3D) printing. The aim of this study was to confirm the effectiveness of this phantom by collecting data to evaluate puncture training.

METHODS

Data from 45 ultrasonography-guided thyroid nodule FNAC procedures performed on our thyroid phantom were evaluated in our department. The first group comprised qualified physicians who specialized in thyroid gland treatment (group A; n = 10). The second and third groups comprised senior and junior residents (group B; n = 8 and group C; n = 12; respectively). The fourth group comprised students (group D; n = 15). We measured the times taken by these groups to complete each task.

RESULTS

The skills of all participants in groups B, C, and D improved after using this phantom involving the major (parallel)- (0.47 ± 0.07) and short (orthogonal)-axes (0.52 ± 0.07) methods (P < 0.001). The number of erroneous punctures decreased from 53 to 3.

CONCLUSIONS

Our original phantom improved the puncture skills of students and junior doctors and was suitable as a tailored training model for practicing thyroid gland transfixion.

Molecular Testing of Atypical Thyroid Nodules with Corresponding Surgical Correlation: Five-Year Retrospective Review in Veterans Population

Objective

We report the results of a retrospective five-year study within a veteran population aimed at correlating abnormal thyroid fine-needle aspiration (FNA) diagnosis with associated molecular testing to the histology of the surgical resection.

Methods

A retrospective analysis of abnormal thyroid FNAs with associated molecular testing and surgical outcome was conducted from January 1, 2015 to December 31, 2020. Aspirates were classified using the Bethesda system for reporting thyroid cytopathology, including atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), suspicious for malignancy (SM), and malignant. Pertinent data, including patient demographics, imaging, and ancillary testing were reviewed. A thyroid cancer mutation panel assessing the most common mutations and rearrangements associated with neoplasia was utilized. The results of molecular testing were directly compared and correlated with final cytological and histological diagnosis.

Results

A total of 1850 thyroid aspirates were performed, 200 of which were given an abnormal cytologic diagnosis. Thirty-six samples were submitted for molecular testing and subsequent surgical follow-up. Four were called malignant on cytology. 32 were placed in an indeterminate category (89%). Within indeterminate cases: 53% exhibited positive molecular mutations (n=17), 34% no mutation detected (n=11), and 13% insufficient quantity for testing (n=4). Upon surgical resection in the mutation-positive group: 18% had no malignancy (n=3), and the remaining 82% were positive for malignancy (n=14). Mutations in the histologically malignant group included: 57% BRAF (n=8), 21% NRAS (n=3), 7% HRAS (n=1), 7% KRAS (n=1), and 7% PAX8/PPAR gamma (n=1). In indeterminate cases with no mutation detected, 10 cases were found to be benign, and one case of malignancy was diagnosed. The probability of indeterminate diagnosis in combination with no mutation yielded a 91% chance of benign entity and 9% chance of malignancy. We demonstrated 93% sensitivity and 91% negative predictive value (NPV) for the risk of malignancy in indeterminate cytology specimens with ancillary molecular testing. There was 77% specificity and 82% positive predictive value (PPV) for our data set.

Conclusions

In indeterminate samples, the detection of a mutation was highly predictive of malignancy and a strong indicating factor for surgery with a high sensitivity and NPV. Molecular testing refined or established the diagnosis in 89% of the cases. Our results indicate that molecular testing of thyroid nodules enhances the accuracy of FNA cytology and the subsequent surgical outcome.

Acute diffuse thyroid swelling after fine-needle aspiration: A case report and review of the literature

Fine-needle aspiration (FNA) is the first-line and a cost-effective examination method of nonfunctional thyroid nodules. Acute transient thyroid swelling after an FNA is a rare complication, and to date, only 14 cases have been reported in the English literature. Herein, we report a case of a 26-year-old woman with acute transient thyroid swelling, which occurred after an ultrasound-guided FNA of a thyroid nodule. Although the patient had undergone an FNA without complication 2 years previously, the second FNA caused acute thyroid swelling. The present case emphasizes the potential risk of acute thyroid swelling associated with every FNA procedure.

Thyroid nodules: diagnostic evaluation based on thyroid cancer risk assessment

Thyroid nodules are extremely common and can be detected by sensitive imaging in more than 60% of the general population. They are often identified in patients without symptoms who are undergoing evaluation for other medical complaints. Indiscriminate evaluation of thyroid nodules with thyroid biopsy could cause a harmful epidemic of diagnoses of thyroid cancer, but inadequate selection of thyroid nodules for biopsy can lead to missed diagnoses of clinically relevant thyroid cancer. Recent clinical guidelines advocate a more conservative approach in the evaluation of thyroid nodules based on risk assessment for thyroid cancer, as determined by clinical and ultrasound features to guide the need for biopsy. Moreover, newer evidence suggests that for patients with indeterminate thyroid biopsy results, a combined assessment including the initial ultrasound risk stratification or other ancillary testing (molecular markers, second opinion on thyroid cytology) can further clarify the risk of thyroid cancer and the management strategies. This review summarizes the clinical importance of adequate evaluation of thyroid nodules, focuses on the clinical evidence for diagnostic tests that can clarify the risk of thyroid cancer, and highlights the importance of considering the patient's values and preferences when deciding on management strategies in the setting of uncertainty about the risk of thyroid cancer.

Correlation Between Oral Lichen Planus and Thyroid Disease in China: A Case-Control Study

BACKGROUND

A possible relationship between oral lichen planus (OLP) and thyroid disease has received attention in recent years.

OBJECTIVE

This study aimed to evaluate the correlation between OLP and thyroid diseases in Chinese ethnic patients.

METHODS

192 OLP patients, 123 patients with oral lichenoid lesions (OLLs), and 162 controls were recruited in this case-control study. All participants received screening for thyroid function and underwent ultrasound. Sex and age of the patients in the three groups were matched. The prevalence of thyroid diseases in the subjects was analyzed. Using logistic regression, the odds ratio (OR) with 95% confidence intervals was appraised for associations between OLP, OLL, and different types of thyroid diseases [Hashimoto's thyroiditis (HT), hypothyroidism, and thyroid nodule].

RESULTS

The prevalence of thyroid diseases in the OLP group (72.4%) and OLL group (68.3%) was higher than the control group (49.4%) with statistical significance. The OR of HT was 3.16 (1.87-5.33) for OLP, 2.09 (1.18-3.70) for OLL, while the OR of thyroid nodule was 2.31 (1.30-4.09) for OLP.

CONCLUSION

Our study suggested a close relationship between OLP/OLL and HT and thyroid nodule in a Chinese population. The possible mechanism behind this association warrants further investigation.

Role of molecular diagnostic markers in the management of indeterminate and suspicious thyroid nodules

Incidental thyroid nodules are commonly found during routine neck examination. Fine needle aspiration (FNA) followed by cytological examination is currently considered as the most reliable method for evaluation of thyroid nodules. However, 10–40% of FNA results are inconclusive, and are reported as indeterminate or suspicious. Approximately 20% of indeterminate or suspicious nodules are malignant. Therefore, there has been an increasing trend in use of molecular markers as an adjunctive measure for more accurate preoperative diagnosis of indeterminate or suspicious nodules. Molecular markers can be used alone or as a part of molecular panels. Although some investigations revealed promising findings regarding the potential use of molecular markers in the management of thyroid nodules, their true impact on management of patients with indeterminate nodules is still unclear.

BRAF and RAS mutations in follicular variants of papillary thyroid carcinoma

Follicular variants of papillary thyroid carcinoma (FVPTC), particularly the encapsulated subtype, often cause a diagnostic dilemma. Therefore, many FVPTCs are interpreted as "indeterminate" in preoperative fine-needle aspiration (FNA). The aim of this study was to analyze the genotypic changes in BRAF codons 600 and 601, as well as the N, H, and KRAS codons 12, 13, and 61 in FVPTCs and investigate the usefulness of preoperative BRAF and RAS mutation analysis as an adjunct diagnostic tool along with routine FNA. Surgically resected thyroid nodules were reviewed to establish the histological diagnosis of FVPTC. All preoperative FNA diagnoses were categorized according to the Bethesda Reporting System. Mutations in BRAF codons 600 and 601, and N, H, KRAS codons 12, 13, and 61 were analyzed by pyrosequencing. Of 132 cases, 81 (61.4 %) had a point mutation in one of the BRAF V600E, BRAF K601E, or RAS oncogenes; BRAF V600E in 43(32.6 %), BRAF K601E in three (2.3 %), and RAS in 35 (26.5 %) cases. All mutations were mutually exclusive. Of 78 cases with an FNA indeterminate category diagnosis, 51 (65.4 %) were positive for mutations: 24 for BRAF V600E, 3 for BRAF K601E, and 24 for the RAS gene. The KRAS mutation was more frequently found than the HRAS mutation, comprising 22.9 % of the RAS mutations, and all KRAS mutations were located at codon 61. This study demonstrated that either BRAF or RAS mutations were present in two thirds of FVPTCs and these mutations were mutually exclusive.

Recent insights into the cell biology of thyroid angiofollicular units

In thyrocytes, cell polarity is of crucial importance for proper thyroid function. Many intrinsic mechanisms of self-regulation control how the key players involved in thyroid hormone (TH) biosynthesis interact in apical microvilli, so that hazardous biochemical processes may occur without detriment to the cell. In some pathological conditions, this enzymatic complex is disrupted, with some components abnormally activated into the cytoplasm, which can lead to further morphological and functional breakdown. When iodine intake is altered, autoregulatory mechanisms outside the thyrocytes are activated. They involve adjacent capillaries that, together with thyrocytes, form the angiofollicular units (AFUs) that can be considered as the functional and morphological units of the thyroid. In response to iodine shortage, a rapid expansion of the microvasculature occurs, which, in addition to nutrients and oxygen, optimizes iodide supply. These changes are triggered by angiogenic signals released from thyrocytes via a reactive oxygen species/hypoxia-inducible factor/vascular endothelial growth factor pathway. When intra- and extrathyrocyte autoregulation fails, other forms of adaptation arise, such as euthyroid goiters. From onset, goiters are morphologically and functionally heterogeneous due to the polyclonal nature of the cells, with nodules distributed around areas of quiescent AFUs containing globules of compact thyroglobulin (Tg) and surrounded by a hypotrophic microvasculature. Upon TSH stimulation, quiescent AFUs are activated with Tg globules undergoing fragmentation into soluble Tg, proteins involved in TH biosynthesis being expressed and the local microvascular network extending. Over time and depending on physiological needs, AFUs may undergo repetitive phases of high, moderate, or low cell and tissue activity, which may ultimately culminate in multinodular goiters.

Benefit of measuring basal serum calcitonin to detect medullary thyroid carcinoma in a Danish population with a high prevalence of thyroid nodules

BACKGROUND

Routine measurement of serum calcitonin to detect medullary thyroid carcinoma (MTC) continues to be fiercely debated, although less attention has been paid to the positive predictive value (PPV) of this method.

METHODS

We collected data from 959 patients with nontoxic nodular goiter; thyroidectomy was performed in 307 of these patients.

RESULTS

Thirty-nine patients had elevated serum calcitonin; 6 of these patients had MTC detected by the initial diagnostic setup. No additional patient in the cohort was registered in the Danish Thyroid Cancer Database, reflecting that all patients with MTC were classified correctly initially. The sensitivity of serum calcitonin for detection of MTC was 100%, the specificity was 95.3%, the positive predictive value was 15.4%, and the negative predictive value was 100%.

CONCLUSION

Serum calcitonin has high sensitivity and specificity for detection of MTC. The low PPV might lead to unnecessary thyroid surgery. Thus, the result of serum calcitonin measurement should always be interpreted in the context of other clinical variables.

A thyroid thriller: acute transient and symmetric goiter after fine-needle aspiration of a solitary thyroid nodule

OBJECTIVE

To report a case of a patient who developed an acute and transient, tender, and bilateral swelling of the thyroid that occurred during fine-needle aspiration (FNA) of a solitary nodule in the left thyroid lobe; to add accurate ultrasound measurements to support our clinical observation; and to analyze a possible underlying mechanism of this rare condition. RESULTS AND CLINICAL FOLLOW-UP: The calculated thyroid volume increased from 23 to 57 mL before and at 4 minutes, respectively, after the needle aspiration, but the thyroid volume returned to prediagnostic level after 4 hours. Cytology, serum calcitonin, and histology were concordant, and the nodule was diagnosed as a medullary thyroid carcinoma. Immunohistochemistry was positive for calcitonin, chromogranin, and the very potent vasodilator calcitonin gene-related peptide (CGRP).

CONCLUSION

This is a rare case of acute and transient thyroid swelling during a common procedure as FNA of a thyroid nodule. This is the first case with documented acute volume expansion quantified by ultrasound measurements supporting our clinical observation, which is in accordance with two historical case reports. The clinical and ultrasound data support the hypothesis of vasodilation as the underlying mechanism, possibly evoked by the release of the vasodilator CGRP.

Early occurrence of RASSF1A hypermethylation and its mutual exclusion with BRAF mutation in thyroid tumorigenesis

Follicular epithelial cell-derived thyroid tumors are common neoplasms comprised mainly of benign thyroid adenomas, follicular thyroid cancers, and papillary thyroid cancers (PTCs). Hypermethylation of the tumor suppressor gene RASSF1A and activating mutation of BRAF gene have been reported recently in thyroid cancers. To additionally investigate the roles of these two epigenetic/genetic alterations in thyroid tumor progression, we examined their occurrences and relationship in both benign and malignant thyroid neoplasms. With real-time quantitative methylation-specific PCR, we found that 4 of 9 (44%) benign adenomas, 9 of 12 (75%) follicular thyroid cancers tumors, and 6 of 30 (20%) of PTC tumors harbored promoter methylation in > or = 25% of RASSF1A alleles. Additional quantitative analysis revealed RASSF1A methylation only in BRAF mutation-negative PTCs. A similar inverse correlation of RASSF1A methylation with BRAF mutation was seen in thyroid tumor cell lines. Our results, therefore, suggest that epigenetic inactivation of RASSF1A through aberrant methylation is an early step in thyroid tumorigenesis. Like the previously reported mutually exclusive relationship between BRAF mutation and other Ras pathway components such as RET/PTC rearrangement, a mutually exclusive relationship also exists between BRAF mutation and RASSF1A methylation in thyroid tumorigenesis.

BRAF T1796A transversion mutation in various thyroid neoplasms

A high prevalence of activating mutation of the B type Raf kinase (BRAF) gene was recently reported in papillary thyroid cancer (PTC). However, the frequency of this mutation in several other types of thyroid neoplasms was not thoroughly investigated. In the present study, in addition to PTC, we evaluated various thyroid tumor types for the most common BRAF T1796A mutation by direct genomic DNA sequencing. We found a high and similar frequency (45%) of the BRAF T1796A mutation in two geographically distinct PTC patient populations: one composed of sporadic cases from North America, and the other from Kiev, Ukraine, that included individuals who were exposed to the Chernobyl nuclear accident. In contrast, we found BRAF mutation in only 20% of anaplastic thyroid cancers and no mutation in medullary thyroid cancers and benign thyroid hyperplasia. We also confirmed previous reports that the BRAF T1796A mutation did not occur in benign thyroid adenomas and follicular thyroid cancers. Specific analysis of the Ukraine patients with confirmed history of radiation exposure failed to show a higher incidence of BRAF mutation. Our results suggest that frequent occurrence of BRAF mutation is inherently associated with PTC, irrespective of geographic origin, and is apparently not a radiation-susceptible mutation. The lack or low prevalence of BRAF mutation in other thyroid neoplasms is consistent with the notion that other previously defined genetic alterations on the same signaling pathway are sufficient to cause tumorigenesis in most thyroid neoplasms.

Management of simple nodular goiter: current status and future perspectives

The simple nodular goiter, the etiology of which is multifactorial, encompasses the spectrum from the incidental asymptomatic small solitary nodule to the large intrathoracic goiter, causing pressure symptoms as well as cosmetic complaints. Its management is still the cause of considerable controversy. The mainstay in the diagnostic evaluation is related to functional and morphological characterization with serum TSH and (some kind of) imaging. Because malignancy is just as common in patients with a multinodular goiter as patients with a solitary nodule, we support the increasing use of fine-needle aspiration biopsy (cytology). Most patients need no treatment after malignancy is ruled out. In case of cosmetic or pressure symptoms, the choice in multinodular goiter stands between surgery, which is still the first choice, and radioiodine if uptake is adequate. In addition to surgery, the solitary nodule, whether hot or cold, can be treated with percutaneous ethanol injection therapy. If hot, radioiodine is the therapy of choice. Randomized studies are scarce, and the side effects of nonsurgical therapy are coming into focus. Therefore, the use of the optimum option in the individual patient cannot at present be based on evidence. However, we are of the view that levothyroxine, although widely used, should no longer be recommended routinely for this condition. Within a few years, the introduction of recombinant human TSH and laser therapy may profoundly alter the nonsurgical treatment of simple nodular goiter.

Minimal access thyroid surgery: is it feasible, is it appropriate?

BACKGROUND

Reports of minimal access thyroid surgery (MATS) using various techniques have recently appeared. This study examined the feasibility of MATS using either a lateral 'focused' or endoscopically assisted approach.

METHODS

The study group comprised all patients undergoing minimally invasive parathyroidectomy (MIP) during the period May 1998 to April 2002 in whom a concomitant thyroid procedure was undertaken. All procedures were performed either through a 2-cm lateral cervical incision (n = 19) or endoscopically (n = 7).

RESULTS

Twenty-six patients underwent thyroid surgery, consisting of either local excision of a thyroid nodule (n = 25) or hemi-thyroidectomy (n = 1). In 13 patients the nodule was incidentally discovered, in four patients removal of the parathyroid necessitated partial thyroidectomy, and in nine patients the lesion identified by preoperative parathyroid localization proved to be a thyroid nodule. There were no permanent complications in the study group. Two patients required drainage of a haematoma. The final pathology of all 26 cases revealed benign nodular thyroid disease.

CONCLUSION

Thyroid surgery can safely be performed as a minimally invasive procedure. Minimal access thyroid surgery is therefore a feasible option for selected patients. The question remains to be answered as to whether this surgical approach is appropriate treatment for nodular thyroid disease.