What does a Bethesda category 2 diagnosis in a Fine Needle Aspiration (FNA) biopsy of a thyroid nodule indicate?

From the Guidelines

Diagnosis and Management of Bethesda Category 2 Thyroid Nodules

A Bethesda category 2 diagnosis in a Fine Needle Aspiration (FNA) biopsy of a thyroid nodule indicates that the nodule is benign.

• Clinical management typically involves monitoring with serial ultrasound examinations 1.
• It is recommended to repeat the ultrasound in 12-24 months to assess for any changes in nodule size or characteristics.
• If the nodule is large or has suspicious features, a follow-up ultrasound may be performed sooner.
• In general, no specific medication is prescribed for Bethesda category 2 nodules, but levothyroxine may be considered if the patient has hypothyroidism or if the nodule is causing compressive symptoms.
• The dose of levothyroxine would depend on the patient's individual thyroid function and clinical status.
• The primary focus is on observation and serial monitoring rather than immediate intervention, given the benign nature of the diagnosis.
• However, clinical judgment should guide the management, taking into account the patient's overall health, the nodule's characteristics, and any changes over time.

From the Research

Bethesda Category 2 Diagnosis

A Bethesda category 2 diagnosis in a Fine Needle Aspiration (FNA) biopsy of a thyroid nodule indicates a benign lesion. The following points summarize the key aspects of this diagnosis:

• A Bethesda category 2 diagnosis is associated with a low risk of malignancy 2.
• The estimated malignancy rate for Bethesda category 2 lesions is not explicitly stated in the provided studies, but it is implied to be low based on the overall context of the Bethesda system 3, 4, 5, 2, 6.
• Clinical and ultrasound factors should be considered when making treatment decisions for patients with thyroid nodules, even those with a benign cytologic diagnosis 3, 4, 6.

Comparison with Other Classifications

The Bethesda system can be compared to other classification systems, such as the Thyroid Imaging Reporting and Data System (TIRADS) or the American Thyroid Association (ATA) guidelines:

• A study found a fair agreement between TIRADS classifications and Bethesda grades, with a higher agreement rate in males than in females 5.
• Another study compared TIRADS with the Bethesda Classification and found an overall concordance rate of 83% with sensitivity and specificity of 70.6 and 90.4%, respectively 6.

Implications for Management

The management of thyroid nodules with a Bethesda category 2 diagnosis may involve:

• Repeat FNA or ultrasound-guided FNA for nodules with suspicious sonographic features or clinical risk factors 3, 4, 6.
• Consideration of clinical and ultrasound factors when making treatment decisions, even for nodules with a benign cytologic diagnosis 3, 4, 6.