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Background: Molecular profiling is currently not yet widespread in Germany and its potential for personalized treatment of solitary thyroid nodules is not exhausted., Method: Narrative assessment of the available options and their evidence based on the current international literature as well as discussion of the options in the German context from the perspective of a thyroid surgeon and a thyroid pathologist., Results: The commercial tests available, especially in the USA, for molecular profiling of thyroid nodules offer good rule-in and somewhat poorer rule-out options, as many differentiated thyroid carcinomas do not display genetic alterations. The costs of these tests and molecular pathology for nodule assessment are still high and the individual mutations have not yet been clearly characterized., Conclusion: It can be assumed that molecular profiling will become more important in the coming years and find its way into the clinical routine. At this point in time, however, there is not yet sufficient evidence of the clinical significance of most mutations in thyroid carcinomas to derive therapeutic consequences from them., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

In the evaluation of thyroid nodules, cytopathology of thyroid fine-needle aspiration specimens plays a central role. Established classification schemes should be used. In the case of indeterminate cytology, additional molecular tests may be used. However, the stratification of indeterminate thyroid nodules into malignant and benign lesions based on molecular tests alone, apart from costly commercial assays from US vendors, has so far been clearly limited. Molecular testing of single genetic alterations that can confirm malignancy in papillary, poorly differentiated, and anaplastic thyroid carcinomas is helpful and relatively easy to perform. However, negative test results by no means exclude malignant neoplasia. Predictive markers for single entities (BRAF V600E, RET mutations and RET fusions) should be tested in all advanced thyroid carcinomas., (© 2022. The Author(s).)

Benefits of Molecular Analyses in Thyroid Carcinoma Abstract. The widespread access to neck ultrasonography has led to high detection rates of thyroid nodules, whose vast majority will remain clinically silent. In daily practice it is a challenge to filter out the thyroid nodules that require medical attention. This is usually achieved by a combination of sonomorphologic criteria and fine-needle aspiration cytology. In recent years, there is a trend toward deescalation in diagnostic and therapeutic measures for thyroid nodules. Some authors even advocate active surveillance instead of surgical approaches for very low-risk thyroid carcinoma. This approach requires an accurate assessment of the malignant potential of each thyroid nodule. As recent studies have allowed better understanding of molecular pathogenesis of thyroid cancer, the mutational profile of thyroid nodules has emerged as a new tool for assessment of thyroid nodules. Its exact clinical application in daily routine remains, however, unclear.

Thyroid nodules are heterogeneous tumors with variable genetic signatures. Thyroid cancers are monoclonal lesions with a defined histomorphology that largely depends on the underlying somatic mutation. While the mutation rate is generally low in differentiated thyroid cancers, poorly differentiated and anaplastic thyroid cancers show a high mutation load. The identification of somatic mutations in fine needle aspirates can be helpful for the differential diagnostics of thyroid nodules; however, a prognostic contribution is less certain. The molecular pathology of thyroid tumors is helpful for the development of targeted therapies and may infer novel immuno-oncological concepts for advanced aggressive thyroid cancers.

Thyroid nodules represent heterogeneous tumors with distinct molecular signatures. While benign thyroid nodules correspond to poly- or monoclonal tumors, thyroid carcinomas are monoclonal and thus "real" neoplasms. These are caused by somatic mutations that lead to the constitutive activation of specific signaling cascades and determine the corresponding histology and also partly the functional phenotype of the thyroid tumor. Dedifferentiation of thyroid carcinomas is accompanied by the occurrence of additional mutations in the tumors. The mutation load of thyroid carcinomas correlates with their biological behavior. In clinical practice, detection of somatic mutations can help in the cytological differential diagnosis. In the prognostic assessment of thyroid tumors, proof of classical oncogene mutations (BRAF, RAS) has little relevance. Other genetic alterations, especially TERT promoter mutations that occur with increasing frequency in advanced thyroid carcinomas, probably have a prognostic significance. The molecular signature, however, is of great relevance for the development and application of targeted therapies in advanced carcinomas (radioactive iodine-refractory DTC, PDTC and ATC, metastatic medullary carcinoma). For this, there is increasing evidence from clinical studies and case reports that underline the concept of "oncogene addiction" as a pathogenetically relevant mechanism of thyroid tumorigenesis and carcinogenesis., Competing Interests: Interessenkonflikt: Die Autoren geben an, dass kein Interessenkonflikt besteht., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background and Objective: Results for the detection of point mutations and rearrangements have thus far been obtained by fresh material of fine needle aspiration cytology (FNAC). After a first retrospective study we report on the diagnostic detection in routinely obtained, consecutive air-dried FNAC smears., Methods: RNA and DNA was extracted from 154 consecutive routine air-dried FNAC smears: 80 with microfollicular proliferation (MFP), 45 with follicular neoplasia (FN), 26 with the cytological diagnosis of papillary carcinomas (PTC) and 3 which were suspicious for malignancy. PAX8/PPARG and RET/PTC3 rearrangements were detected by qPCR, while BRAF and RAS point mutations were detected by pyrosequencing., Results: Only 0.7 % and 5.3 % of the routine air-dried FNAC samples did not allow analysis of a point mutation or rearrangements, respectively. NRAS mutations could be detected in 7 MFP smears, and in one of FN and PTC samples, respectively. HRAS mutations were detected in one MPF and one FN sample. A KRAS mutation was only detected in one FN sample, whereas BRAF mutations were detected in 20 samples with PTC (but in no other sample). PAX8/PPARG was detected in 2 MFP samples, while RET/PTC was detected in only one MFP sample. In total, 13.8 % MFP-FNAC, 6.7 % FN-FNAC, and 80.8 % PTC-FNAC samples harbored a mutation., Conclusion: These results demonstrate that rearrangements and point mutations can be detected in routinely obtained air-dried FNAC samples., (© Georg Thieme Verlag KG Stuttgart · New York.)

MicroRNAs (miRNAs) are small (20-24 nucleotides), non-coding ribonucleid acids, which regulate gene expression on the post-transcriptional level, thus influencing physiological processes including cellular growth, differentiation and apoptosis. Several miRNAs (e. g. miRNAs 146b, 221 and 222) have been shown to be consistently over-expressed in papillary thyroid carcinoma. The present overview describes and discusses the utilization and problems of miRNA analysis in material from thyroid nodules obtained by fine needle biopsy. Particularly the analysis of defined sets of miRNAs should improve the diagnostic value of this procedure and contribute to a better management of patients with cold thyroid nodules.

Autonomously functioning thyroid nodules are frequently associated with mutations of the thyrotropin receptor. We analyzed a part of exon 10 of the thyrotropin receptor gene (base pairs 1762-1976) by direct sequencing and found missense mutations in 5 of 14 cases (codons 629, 631, 632, 633). Histologically, 3 of the 14 nodules were adenomas whereas 11 were hyperplasias. Nodules with mutations did not show significant differences from nodules without mutations with respect to age, histology, size, additional (non-functional) nodules and clinical symptomatology. Our results confirm that thyrotropin receptor mutations are involved in the development of autonomously functioning thyroid nodules. In this context, the terms hyperplasia and neoplasia should be reevaluated.

Seventeen autonomously functioning thyroid nodules (AFTN) were analyzed for the most frequent mutations of the thyrotropin (TSH) receptor gene at codons 619, 631, 632 and 633. DNA was extracted from formalin-fixed, paraffin-embedded samples from both nodules and surrounding tissue after micro- or macrodissection. A fragment of the TSH receptor gene (bp 1762-1976) encoding the third cytoplasmic loop and the sixth transmembranous domain was amplified by PCR. Screening for mutations at codons 619, 631, 632 and 633 was performed by restriction enzyme analysis using Asp 718, Hph I, Taq I and EcoR I, respectively. For verification, cases with a mutated restriction site were cloned and sequenced. Mutations were found in 3 AFTNs (18%): in 2 cases at codon 632 and in 1 case at codon 631. The 2 cases with a mutation at codon 632 harbored additional mutations at codon 599 and 640, respectively, detected by sequencing. Normal thyroid tissue outside the AFTNs did not harbor mutant TSH-receptor. Mutations occurred in patients with clinical and subclinical hyperthyroidism. Mutations were associated both with total (2 cases) and partial (1 case) suppression of the surrounding thyroid tissue as noted on the scinti scan. AFTNs with TSH-receptor mutation occurred as single nodules. All 3 nodules with mutations were classified histologically as nodular hyperplasia according to the criteria of the WHO. Although the number of cases is small, our data suggest that AFTNs are clinically and morphologically heterogenous. Since the most common TSH-receptor mutations occur only in a small subset of AFTNs other molecular genetic alterations may be involved in the development of AFTNs.

TSH receptor stimulating antibodies (TSAb) are well known in the pathogenesis of Graves' disease. Recently mutations in the DNA coding for the TSH-receptor (TSHR) have been revealed in autonomously functioning thyroid nodules (AFTN). In this study we looked for mutations in 9 patients with AFTN. DNA was extracted separately from the nodules and the paranodular thyroid tissues. A fragment of the TSHR gene (bp 1762-1976) was amplified by PCR. The amplified DNA was digested with Hph I, Taq I, Kpn I and Eco RI, respectively, and the resulting fragments were analyzed by gel electrophoresis. Mutations were detected in the nodules of 3 of the 9 patients. In the nodules of 2 patients we found simultaneous mutations affecting the restriction sites of Hph I and Taq I. In the 3rd patient a mutation affecting the restriction site of Hph I was observed. The simultaneous occurrance of TSHR-mutations altering Hph I (Position 631) and Taq I (position 632) restriction sites in AFTN have not been described so far.

Recent advances in thyroid research are reviewed which reflect fundamental changes in understanding of the pathogenesis of thyroid adenomas, and of clonal and polyclonal goiter nodules. It is generally accepted that chronic iodine deficiency leads to the development of a diffuse homogeneous goiter. However, low iodine supply does not explain generation and growth of thyroid nodules and the characteristic functional heterogeneity of most nodular goiters. Molecular analyses of recent years have revealed that thyroid adenomas and most nodules in goiters, even if morphologically heterogeneous, are clonal and thus true benign tumors. This has been demonstrated in areas both with iodine deficiency and with sufficient iodine supply. However, in areas with iodine deficiency, chronic stimulation accelerates the genesis of nodules and adenomas. The molecular pathogenesis of these tumors is still unknown. Only in a subgroup of toxic adenomas mutations of the TSH receptor and the Gs-alpha gene have recently been found that may explain the genesis of these tumors and the development of hyperthyroidism in patients with these adenomas.