What is the appropriate monitoring for a follicular nodule in the thyroid gland?

From the Guidelines

Fine needle aspiration (FNA) is not required for thyroid nodules measuring less than 1 cm, and decisions to aspirate larger nodules should be guided by lesion size and sonographic appearance. When monitoring follicular nodules, follow-up ultrasound is typically recommended at 6-12 months initially, then annually for 3-5 years if stable 1. Repeat FNA should be considered if the nodule grows significantly, generally defined as a 20% increase in at least two dimensions with a minimum increase of 2mm, or a 50% increase in volume. The decision to perform FNA initially depends on nodule size and ultrasound characteristics, such as hypoechoic, microcalcifications, irregular margins, and taller-than-wide shape 1.

Key Considerations

• Nodules larger than 1-1.5cm with suspicious features should undergo FNA, while smaller nodules may be monitored with ultrasound alone 1.
• Most thyroid nodules are benign and grow slowly, and this monitoring approach balances the need to detect potential malignant transformation against avoiding unnecessary procedures 1.
• If a nodule shows continued growth or develops suspicious features during monitoring, surgical consultation may be warranted even with benign cytology 1.
• Molecular profiling, including assessment of malignancy markers and molecular alterations, can facilitate FNA-based diagnosis and identify malignancy when cytology samples are morphologically indeterminate 1.

Monitoring and Follow-up

• Follow-up ultrasound is recommended at 6-12 months initially, then annually for 3-5 years if stable 1.
• Repeat FNA should be considered if the nodule grows significantly, or if suspicious features develop during monitoring 1.
• Surgical consultation may be warranted if a nodule shows continued growth or develops suspicious features during monitoring, even with benign cytology 1.

From the Research

Monitoring of Follicular Nodules in the Thyroid

• The diagnosis and management of follicular-patterned thyroid lesions can be achieved through fine needle aspiration (FNA) 2.
• FNA is used as a screening test to identify benign nodules and differentiate them from malignant ones, with a category of "atypical cells of undetermined significance" (ACUS) for lesions that cannot be easily classified 2.
• The recommended follow-up for an ACUS diagnosis is clinical correlation and repeat FNA sampling 2.

Role of Fine-Needle Aspiration in Thyroid Nodule Evaluation

• Fine-needle aspiration biopsy (FNA) is the standard test to determine whether surgical removal of a detected nodule is recommended 3.
• FNA has an essential role in the evaluation of patients with thyroid nodules to reduce the rate of unnecessary thyroid surgery for patients with benign nodules and triage patients with thyroid cancer to appropriate surgery 3.
• The use of FNA has increased the percentage of resected thyroid nodules that are malignant, from approximately 14% to over 50% 3.

Management of Follicular Patterned Lesions

• The National Cancer Institute (NCI) State of the Science Conference on thyroid FNA proposed that follicular patterned lesions can be divided into two diagnostic categories: follicular lesion of undetermined significance/Atypia of undetermined significance (FLUS/AUS) and suspicious for follicular neoplasm/follicular neoplasm (SFON/FON) 4.
• Repeat FNA (RFNA) can be beneficial for lesions classified as FLUS/AUS to achieve a more definitive diagnosis, while lesions classified as SFON/FON should undergo surgical excision for histologic characterization 4.
• RFNA is effective in managing thyroid nodules diagnosed as FLUS/AUS, as it can help differentiate between benign and malignant lesions 4.

Diagnostic Approaches for Follicular Neoplasms

• Fine-needle aspiration (FNA) is a common diagnostic approach for follicular neoplasms, but it has limitations due to its relatively high false-positive rate 5.
• Core-needle biopsy (CNB) has been shown to have a lower false-positive rate and a higher malignancy rate than FNA in diagnosing follicular neoplasms, making it a potentially useful diagnostic tool 6.
• CNB can help minimize unnecessary surgery and provide diagnostic confidence when managing patients with follicular neoplasms 6.