Guidance for the management of thyroid nodules has evolved over time, from initial evaluation based predominantly on clinical grounds to now including the established role of ultrasound and fine needle aspiration cytology in their assessment. There is, however, significant variation in the management of thyroid nodules depending on which national guidelines are followed. In addition, there are certain clinical situations such as pregnancy and paediatric thyroid nodules that have differing evaluation priorities.

This review aimed to provide an overview of currently accepted practices for the initial investigation and subsequent management of patients with thyroid nodules for the non-specialist. The review also addresses areas of variance between the systems in common clinical use, as well as newer, evolving technologies, including molecular testing in the evaluation of malignancy in thyroid nodules.

To explore the diagnostic value of anteroposterior-to-transverse ratio for predicting thyroid cancer.

A total of 2306 nodules were divided into 5 groups according to their size. The ability of the anteroposterior-to-transverse ratio to predict thyroid cancer was analysed in each group on the basis of the sensitivity, specificity, accuracy and Youden index.

The median anteroposterior-to-transverse ratio was 0.83, with an interquartile range of 0.28. The area under the receiver operating characteristic curve was 0.709 (p < 0.001). When the diameter of a thyroid nodule was less than 1.5 cm, an anteroposterior-to-transverse ratio of more than 0.9 was associated with higher sensitivity, accuracy and Youden index, compared with an anteroposterior-to-transverse ratio of greater than 1.0, but the specificity was lower. When the diameter of a thyroid nodule was 1.5 cm or more, an anteroposterior-to-transverse ratio of greater than 0.9 was associated with higher sensitivity and Youden index, compared with an anteroposterior-to-transverse ratio of greater than 1.0, but specificity and accuracy were lower.

The anteroposterior-to-transverse ratio was a meaningful indicator of thyroid cancer, and its predictive effectiveness could be influenced by nodule size.

The coronavirus disease 2019 pandemic requires urgent modification to existing head and neck cancer diagnosis and management practices. A protocol was established that utilises risk stratification, early investigation prior to clinical review and a reduction in aerosol generating procedures to lessen the risk of coronavirus disease 2019 spread.

Two-week wait referrals were stratified into low, intermediate and high risk. Low risk patients were referred back to primary care with advice; intermediate and high risk patients underwent investigation. Clinical encounters and aerosol generating procedures were minimised. A combined diagnostic and therapeutic surgical approach was undertaken where possible.

Forty-one patients were used to assess feasibility. Thirty-one per cent were low risk, 35 per cent were intermediate and 33 per cent were high risk. Thirty-three per cent were discharged with no imaging.

Implementing this protocol reduces the future burden on tertiary services, by empowering primary care physicians to re-refer low risk patients. The protocol is applicable across the UK and avoids diagnostic delay.

To explore the use of fluorescence lifetime imaging microscopy in thyroid tissues, and to investigate how different thyroid lesions affect fluorescence lifetime.

Fluorescence lifetime measurements were taken of fresh frozen thyroid surgical specimens stained with fluorescein isothiocyanate tagged anti-thyroglobulin monoclonal antibodies.

The mean fluorescence lifetime measurements in 12 patients – 3 with multinodular goitre, 4 with follicular adenoma, 4 with papillary thyroid carcinoma and 1 with follicular carcinoma – were 3.16 ns (range, 2.66–3.52 ns), 3.75 ns (range, 2.99–4.57 ns), 2.97 ns (range, 2.57–3.21 ns) and 3.61 ns, respectively. The fluorescence lifetime of follicular adenoma patients was higher than that of papillary thyroid carcinoma patients by 26 per cent (p = 0.058). The fluorescence lifetime in the follicular carcinoma patient was similar to the follicular adenoma group, but higher than in the papillary thyroid carcinoma group by 22 per cent (p = 0.01).

Fluorescence lifetime measurements varied in different thyroid pathologies, possibly because of tissue-scale structural influences.

To determine the prevalence of thyroid malignancy in the first UK case series of patients with incidentally detected thyroid lesions on 18F-fluorodeoxyglucose positron emission tomography imaging.

A total of 235 patients were evaluated with 18F-fluorodeoxyglucose positron emission tomography imaging. Incidental focal uptake in the thyroid gland was identified in nine patients (3.8 per cent). A retrospective review of their case notes was conducted.

The rate of malignancy was 55 per cent. The mean and standard deviation of the maximum standardised uptake value was 13.1 ± 7.3 in those patients with malignancy and a nodule identified as positive on positron emission tomography. This value was 2.8 ± 1.2 in those patients without malignancy but with a nodule identified as positive on positron emission tomography (p = 0.01). A palpable thyroid nodule was more likely in those with malignant lesions (p = 0.14).

The prevalence of incidental thyroid lesions found on 18F-fluorodeoxyglucose positron emission tomography in patients with other primary malignancies is low, but the incidence of malignancy in these patients is high. Patients with a palpable thyroid nodule, focal uptake on 18F-fluorodeoxyglucose positron emission tomography and an increased maximum standardised uptake value require further investigation.

‘R staging’ is a new ultrasonographic scoring system developed and used by our specialist head and neck radiologist for reporting sonographic risk of malignancy to those at our thyroid multidisciplinary team meeting. This study aimed to: classify the R staging system, examine its relationship with the eventual histopathological diagnosis and define its clinical utility.

The pre-operative ultrasound scans of 78 patients were assigned an R status by our specialist head and neck radiologist. The final histopathology report for each thyroid nodule was used as the ‘gold standard’ for analysis.

When thyroid nodules were classified as low risk (R stages 1–3) or high risk (R stages 4–5) for malignancy, the sensitivity of R staging was 74.2 per cent and specificity was 80.9 per cent. An R5 status was 100 per cent predictive of malignancy.

Our results compare favourably with other suggested ultrasonographic staging systems for thyroid nodules.

Papillary microcarcinoma of the thyroid has been described as either a normal variant or a serious malignancy. We describe our experience with papillary microcarcinoma and lymph node metastases.

A total of 685 consecutive total thyroidectomies with central compartment neck dissection were reviewed for papillary microcarcinoma. Association of central compartment lymph node metastases with age, gender, tumour multifocality, bilaterality and extrathyroidal extension was analysed.

Out of 170 papillary microcarcinoma cases, multifocality was found in 72 (42.4 per cent), bilaterality in 49 (28.8 per cent) and extrathyroidal extension in 16 (9.4 per cent). In all, 23 patients (13.5 per cent) had lymph node metastases. There was a significant association (p < 0.05) between extrathyroidal extension (but no other tumour characteristics) and lymph node metastases.

In all, 13.5 per cent of papillary microcarcinomas in our series showed lymph node metastases. Lymph node metastases were associated with extrathyroidal invasion of the papillary microcarcinoma.