Clinically detectable thyroid nodules are less common in children than adults. However, they are associated with an increased risk of malignancy. Therefore, thorough evaluation of paediatric thyroid nodules is necessary, and an understanding of the features associated with a higher risk of malignancy is important to guide management and referral. Thyroid cancer in children differs significantly from that seen in adults in terms of genetics, presentation, response to treatment and prognosis. Children often present with more advanced disease, but the vast majority have excellent long‐term prognosis. Evaluation and management of thyroid nodules and thyroid cancer require a multidisciplinary team approach and involvement of specialists with experience in this field. This review summarises investigative pathways for thyroid nodules in children and outlines current management strategies for paediatric thyroid nodules and cancer.

The aim of this cross-sectional study was to compare plasma C-peptide presence and levels in people without diabetes (CON) and with Type 1 diabetes and relate C-peptide status to clinical factors. In a subset we evaluated 50 microRNAs (miRs) previously implicated in beta-cell death and associations with clinical status and C-peptide levels. Diabetes age of onset was stratified as adult (≥ 18 y.o) or childhood (< 18 y.o.), and diabetes duration was stratified as ≤ 10 years, 10–20 years and > 20 years. Plasma C-peptide was measured by ultrasensitive ELISA. Plasma miRs were quantified using TaqMan probe-primer mix on an OpenArray platform. C-peptide was detectable in 55.3% of (n = 349) people with diabetes, including 64.1% of adults and 34.0% of youth with diabetes, p < 0.0001 and in all (n = 253) participants without diabetes (CON). C-peptide levels, when detectable, were lower in the individuals with diabetes than in the CON group [median lower quartile (LQ)–upper quartile (UQ)] 5.0 (2.6–28.7) versus 650.9 (401.2–732.4) pmol/L respectively, p < 0.0001 and lower in childhood versus adult-onset diabetes [median (LQ–UQ) 4.2 (2.6–12.2) pmol/L vs. 8.0 (2.3–80.5) pmol/L, p = 0.02, respectively]. In the childhood-onset group more people with longer diabetes duration (> 20 years) had detectable C-peptide (60%) than in those with shorter diabetes duration (39%, p for trend < 0.05). Nine miRs significantly correlated with detectable C-peptide levels in people with diabetes and 16 miRs correlated with C-peptide levels in CON. Our cross-sectional study results are supportive of (a) greater beta-cell function loss in younger onset Type 1 diabetes; (b) persistent insulin secretion in adult-onset diabetes and possibly regenerative secretion in childhood-onset long diabetes duration; and (c) relationships of C-peptide levels with circulating miRs. Confirmatory clinical studies and related basic science studies are merited.

Purpose of Review: Paediatric thyroid cancer management traditionally relied on extrapolation from adult data and, despite good survival outcomes, often involved extensive surgical approaches and radioactive iodine (RAI) therapy with potentially life‐long complications. Increasing understanding of paediatric diagnostic techniques, molecular tumour drivers and targeted therapies will allow a more nuanced, disease‐specific comprehensive model of care. This review summarises recent developments in paediatric thyroid cancer biology, diagnosis and models of care.Methods: Review of relevant literature from the last 5 years to inform a narrative summary by a multidisciplinary team of clinician experts in paediatric thyroid cancer management.Findings: Standardised risk scoring systems will likely improve the objectivity and accuracy of paediatric thyroid nodule risk stratification on ultrasound, but further studies are needed to validate these. Identification of somatic and germline gene variants is playing a rapidly increasing role in paediatric thyroid cancer diagnosis and planning of surgical approaches and neoadjuvant and adjuvant therapies. There is growing recognition that lobectomy may achieve comparable outcomes, with reduced risk of complications, to total thyroidectomy in patients with low‐risk disease. Molecularly targeted therapies are now available for the management of advanced disease as an adjuvant, and likely neo‐adjuvant, therapy for medical debulking of large tumours and resensitisation of RAI‐resistant disease.Conclusions: The management pathways for paediatric thyroid cancer are rapidly evolving due to the increasing availability of paediatric‐specific data. As management options become more complex, interdisciplinary collaboration and shared decision‐making are ever more important.

Background: The understanding of the molecular basis of paediatric thyroid carcinoma has expanded rapidly in the last decade. Most carcinomas are associated with de novo somatic gene alterations that confer distinct clinicopathological characteristics. In comparison to adults, paediatric carcinomas are less commonly associated with point mutations and more commonly with gene fusions, which are characterised by more-invasive disease. Cancer predisposition genes play an important role in a small percentage of tumours, and the family history and the recognition of other syndromic features are key to identifying these patients. Molecular testing platforms for clinical use have been developed and validated in adults, and their use is becoming established in the management of indeterminate thyroid nodules, where they significantly reduce the rates of diagnostic lobectomy. Paediatric data are more limited than adult data, and the role of molecular testing in paediatric thyroid carcinoma management is evolving. Methods: This review describes the current knowledge of molecular alterations in paediatric thyroid carcinomas, evidence supporting molecular testing in clinical practice, and future directions for research. Results and Conclusions: A molecular diagnosis enables the use of molecularly targeted therapies for children and adolescents with advanced or radioiodine-refractory disease. There is also great potential for molecular testing to improve the accuracy of the risk-stratification of paediatric thyroid nodules, reducing surgical intervention and complications without negatively impacting outcomes, and data to support such an approach are emerging.