Updates in Thyroid Cytology

Management of thyroid tumors diagnosed cytologically as follicular neoplasms in a high-volume center: utility of a scoring system using serum thyroglobulin level, tumor size, ultrasound testing, and cytological diagnosis

Managing thyroid nodules diagnosed cytologically as follicular neoplasms (FN) is challenging for patients and clinicians. Gene panel testing was recently introduced to determine the management strategy for FN; however, it is unavailable in Japan. In this study, we assessed FN management. This study included 2,144 FNs from 2,067 patients diagnosed between 2012 and 2018. Of these, 952 (44.5%) tumors underwent active surveillance, and 1,188 (55.6%) underwent immediate surgery (IS). Tumors of young patients (<55 years), male patients, and patients with serum thyroglobulin (Tg) ≥500 ng/mL, ultrasound diagnoses as FN or malignancy, large tumors (>4 cm), non-oxyphilic cytology, and cytological findings favoring malignancy and multiplicity underwent IS more frequently. Of the 1,412 tumors that underwent surgery, 279 (19.8%) and 1,133 (80.2%) were pathologically diagnosed as malignant and benign tumors or low-risk neoplasms, respectively. High Tg levels, non-benign ultrasound findings, cytological findings favoring malignancy, non-oncocytic cytology, and large tumor size were related to malignant pathology; however, tumor enlargement was not. The former three were independent predictors of malignancy in the multivariate logistic analysis. After assigning scores of 2 and 1 for cytological findings favoring malignancy and others, respectively, a receiver operating characteristic curve analysis indicated a score of 3 as the optimal cutoff for predicting malignant diagnosis; however, the area under the curve remained low, at 0.642. Accurately predicting the malignant pathology of FNs is challenging, and inducing gene panel testing will be helpful for managing FN tumors. Our scoring system would also be useful in estimating the risk of malignancy.

The gray zone of thyroid nodules: Using a nomogram to provide malignancy risk assessment and guide patient management

Background

Thyroid nodules have a low prevalence of malignancy and most proven cancers do not behave aggressively. Thus, risk‐stratification of nodules is a critical step to avoid surgical overtreatment. We hypothesized that a risk management system superior to those currently in use could be created to reduce the number of clinically indeterminate nodules (i.e., the “gray zone”) by concurrently considering the malignancy risks conferred by clinical, ultrasonographic, and cytologic variables.

Methods

Thyroidectomy cases were reviewed from three institutions. Their benign versus malignant outcome was used to evaluate the variables for correlation. A binary logistic regression model was trained and, using indeterminate nodules with Bethesda III and IV results, validated. A scoring nomogram was designed to demonstrate the application of the model in clinical practice.

Results

One hundred thirty thyroidectomies (28% malignant) met inclusion criteria. The final logistic regression model included difficulty in swallowing, hypothyroidism, echogenicity, hypervascularity, margins, calcification, and cytology diagnosis as input parameters. The model was highly successful in determining the outcome (p value: 0.001) with a R²(Nagelkerke) score of 0.93. The area under the curve as determined by receiver operating characteristics was 0.91. The accuracy of the model on the training dataset was 93% (sensitivity and specificity 92% and 96%, respectively) and, on the validation dataset, 80% (sensitivity and specificity 91% and 67%, respectively).

Conclusions

We report a model for risk assessment of thyroid nodules that has the potential to significantly reduce indeterminates and surgical overtreatment. We illustrate its application via a straightforward nomogram, which integrates clinical, ultrasonographic, and cytologic data, and can be used to create clear, evidence‐based management plans for patients.