Thyroid Ultrasound > Nodule Management > US-Guided Biopsy


US-Guided Biopsy

The discussion of the technique for performing a thyroid nodule biopsy is not a focus of this tutorial. If you are interested, the following 2008 Radiographics article provides an excellent source: 

"US-guided Fine-Needle Aspiration of Thyroid Nodules: Indications, Techniques, Results" by Kim MJ, et al.

Circumstances that necessitate repeat FNA include sample inadequacy, nodule enlargement, cyst recurrence, or clinical or imaging findings that arouse suspicion about the presence of a malignancy even when cytologic findings in the biopsy specimen indicate benignity.

 

The American Thyroid Association Guidelines Taskforce 2006 (direct quotes): 

"Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer" by Cooper DS, et al.

FNA is the procedure of choice in the evaluation of thyroid nodules 

- Nondiagnostic aspirates:
Cystic nodules that repeatedly yield nondiagnostic aspirates need close observation or surgical excision. Surgery should be more strongly considered if the cytologically nondiagnostic nodule is solid.

- Aspirates suggesting malignancy:
If a cytology result is diagnostic of malignancy, surgery is recommended.

- Indeterminate cytology:
If the cytology reading is indeterminate (often termed “suspicious,” “follicular lesion,” or “follicular neoplasm”), a radioiodine thyroid scan should be considered, if not already done. If a concordant autonomously functioning nodule is not seen, lobectomy or total thyroidectomy should be considered.

If the reading is “suspicious for papillary carcinoma or Hürthle cell neoplasm,” a radionuclide scan is not needed, and either lobectomy or total thyroidectomy is recommended.

- Benign cytology:
If the nodule is benign on cytology, further immediate diagnostic studies or treatment are not routinely required

- Multinodular goiters:
Patients with multiple thyroid nodules have the same risk of malignancy as those with solitary nodules. A diagnostic ultrasound should be performed to delineate the nodules, but if only the “dominant” or largest nodule is aspirated, the thyroid cancer may be missed. Sonographic characteristics are superior to nodule size for identifying nodules that are more likely to be malignant and include the presence of microcalcifications, hypoechogenicity of a solid nodule, and intranodular hypervascularity. 

In the presence of two or more thyroid nodules larger than 1–1.5 cm, those with a suspicious sonographic appearance should be aspirated preferentially.

If none of the nodules has a suspicious sonographic appearance and multiple sonographically similar coalescent nodules are present, the likelihood of malignancy is low and it is reasonable to aspirate the largest nodules only
A low or low-normal serum TSH concentration may suggest the presence of autonomous nodule(s). A radioiodine scan should be performed and directly compared to the ultrasound images to determine functionality of each nodule larger than 1–1.5 cm. FNA should then be considered only for those isofunctioning or nonfunctioning nodules, among which those with suspicious sonographic features should be aspirated preferentially.



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