Does a 0.1 cm increase in size of a previously benign (in 2018) 3.1 cm thyroid nodule (TR4) to 3.2 cm warrant a re-biopsy?

From the Guidelines

A 0.1 cm increase in size of a previously benign 3.1 cm thyroid nodule (TR4) to 3.2 cm does not typically warrant a re-biopsy on its own. This small change falls within the margin of measurement error and is not considered clinically significant growth. For thyroid nodules with previous benign cytology, re-biopsy is generally recommended when there is significant growth (usually defined as a 20% increase in at least two dimensions with a minimum increase of 2 mm) or when there are new suspicious sonographic features, as suggested by the American College of Radiology Appropriateness Criteria for thyroid disease 1. In this case, the growth is only about 3%, which is minimal. However, the TR4 classification indicates an intermediate suspicion for malignancy, so regular monitoring should continue with ultrasound follow-up in 6-12 months, as recommended by the European Society for Medical Oncology guidelines for diagnosis, treatment, and follow-up of thyroid cancer 1. If more rapid growth occurs in the future, new suspicious features develop, or if the patient develops symptoms like difficulty swallowing or voice changes, then re-biopsy would be appropriate. The decision should also consider the patient's risk factors, the quality of the initial biopsy, and any clinical symptoms. Some key points to consider in the management of thyroid nodules include:

• The use of fine-needle aspiration cytology (FNAC) as an important technique for the diagnosis of thyroid nodules, particularly for those with suspicious sonographic features or a history of head and neck irradiation 1.
• The importance of considering the patient's risk factors, such as family history of thyroid cancer, in the decision to perform a re-biopsy.
• The role of ultrasound in monitoring thyroid nodule growth and detecting new suspicious features, as recommended by the American College of Radiology Appropriateness Criteria for thyroid disease 1.

From the Research

Thyroid Nodule Size Increase and Re-Biopsy

• A 0.1 cm increase in size of a previously benign 3.1 cm thyroid nodule to 3.2 cm may not necessarily warrant a re-biopsy, as the increase in size is relatively small.
• According to the study by 2, significant nodule growth (SNG) is common in benign thyroid nodules, but malignancy is quite rare in growing nodules.
• The American College of Radiology Thyroid Imaging Reporting and Data System committee published a standardized approach to classifying nodules on ultrasound, which can help determine which nodules demonstrate malignant features 3.
• The study by 4 found that thyroid nodule size is inversely related to malignancy risk, as larger nodules have lower malignancy rates.
• However, the relationship of size to malignancy varies by FNA status, and size alone should not be considered as an independent risk factor 4.
• The study by 5 found that a large nodule size does not contribute to the risk of malignancy or the risk of a false-negative FNA, and that a large nodule size should not prompt automatic referral for thyroidectomy.
• The decision to re-biopsy a thyroid nodule should be based on a personalized, risk-based protocol that takes into account the estimated risk of malignancy and the presence and severity of compressive symptoms 6.

Factors to Consider

• The initial risk estimate, derived from ultrasound and, if performed, cytology report, should determine the need for treatment and the type, frequency, and length of subsequent follow-up 6.
• Factors associated with significant nodule growth (SNG) include being younger than 45 years of age, having a higher number of nodules, and having smaller nodule volume 2.
• The Thyroid Imaging Reporting and Data System can help identify nodules that demonstrate malignant features and reduce the number of unnecessary biopsies 3.