What are the guidelines for managing a 2.5 centimeter (cm) thyroid nodule?

From the Guidelines

For a 2.5 cm thyroid nodule, fine needle aspiration (FNA) biopsy is strongly recommended as the initial diagnostic step. This size falls into the category where malignancy risk is significant enough to warrant evaluation, regardless of ultrasound characteristics 1. Prior to biopsy, a comprehensive neck ultrasound should be performed to assess nodule characteristics (solid vs. cystic, echogenicity, margins, calcifications, vascularity) and to check for suspicious lymph nodes. Thyroid function tests (TSH, free T4) should also be obtained to determine functional status of the nodule.

• The initial treatment for differentiated thyroid carcinoma (DTC) is total or near-total thyroidectomy whenever the diagnosis is made before surgery and the nodule is ≥1 cm, or regardless of the size if there is metastatic, multifocal or familial DTC 1.
• If the FNA results are benign, follow-up ultrasound is typically recommended in 6-12 months to monitor for growth.
• If results are malignant or suspicious, referral to an endocrinologist and surgeon for potential thyroidectomy is indicated.
• For indeterminate results, molecular testing of the sample may help determine malignancy risk.
• Patients should be monitored for compressive symptoms such as difficulty swallowing, voice changes, or breathing problems, which might necessitate surgical intervention regardless of biopsy results. The 2.5 cm size is significant because nodules larger than 2 cm have a higher statistical risk of malignancy, with risk increasing proportionally with size.

From the Research

Guidelines for Managing a 2.5 cm Thyroid Nodule

The management of a 2.5 cm thyroid nodule involves a systematic and careful diagnostic evaluation to determine whether the nodule is benign or malignant.

• Fine-needle aspiration (FNA) biopsy is a safe, useful, and cost-effective procedure that plays a central role in the diagnostic investigation of thyroid nodules 2, 3, 4, 5.
• FNA biopsy can be performed under ultrasonographic guidance to increase accuracy, especially for nodules with suspicious clinical findings or ultrasound features suggestive of malignancy 2, 5.
• The results of FNA biopsy can be categorized as diagnostic or nondiagnostic, and diagnostic specimens are classified as benign, "suspicious," or malignant 3, 4.
• Rebiopsy is indicated for enlarging nodules, recurrent cysts, and nondiagnostic cytologic findings 3.
• The risk of malignancy in thyroid nodules increases with size, but the diagnostic accuracy of FNA biopsy remains high even for larger nodules 6.
• Surgical treatment is recommended for malignant nodules, while benign nodules may be managed conservatively 2, 4.
• A standardized and meticulous technique for FNA biopsy is essential for lowering the yield of nondiagnostic specimens and false-negative results 5.

Diagnostic Evaluation

• FNA biopsy is the preferred initial diagnostic test for thyroid nodules, rather than thyroid scanning or ultrasonography 4.
• Ultrasonography can be used to guide FNA biopsy and increase accuracy 2, 5.
• The diagnostic accuracy of FNA biopsy approaches 95%, with negative (benign) and positive (malignant) cytologic results being conclusive 4.
• Nondiagnostic results are inconclusive and require further evaluation by repeated FNA biopsy, ultrasound-guided biopsy, or radionuclide scanning 4.
• Suspicious cytologic results are also inconclusive and are associated with a 20% chance of malignant involvement, requiring surgical treatment for clarification 4.

Management of Thyroid Nodules

• Malignant thyroid nodules should be managed surgically, while benign nodules may be managed conservatively 2.
• The role of levothyroxine therapy in the management of thyroid nodules remains uncertain and is not recommended until compelling data are available 4.
• Surgical excision is recommended for nodules with suspicious or malignant cytologic results, as well as for enlarging nodules or recurrent cysts 3, 4.