What is the diagnosis and management for a patient with a Fine Needle Aspiration (FNA) result of the right thyroid showing thin colloid with rare clusters and single small follicular epithelial cells?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: February 3, 2026 • View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

Bethesda Category II (Benign): Colloid Nodule

Your FNA result showing thin colloid with rare clusters and single small follicular epithelial cells is consistent with Bethesda Category II (Benign), most likely representing a benign colloid nodule or nodular goiter, and the recommended management is clinical and ultrasound surveillance rather than surgery. 1

Cytologic Interpretation

  • Thin colloid with rare follicular cells is the classic cytologic pattern of a benign colloid nodule, which falls into Bethesda Category II with a malignancy risk of only 1-3% 1

  • The presence of abundant colloid combined with sparse, regularly-spaced follicular epithelial cells strongly predicts a macrofollicular or mixed architectural pattern on histology, which is associated with benign disease 2

  • This cytologic pattern (thin/watery colloid with scant follicular cells) has been validated as highly predictive of benign nodular goiter or colloid goiter in multiple studies 3, 4

Risk Stratification

  • Bethesda II nodules carry an extremely low malignancy risk of 1-3%, which does not justify surgical intervention in the absence of compressive symptoms or highly suspicious clinical features 1

  • The diagnostic accuracy of FNA for benign thyroid nodules approaches 95%, making this a highly reliable result 1

  • False-negative rates for Bethesda II are only 1.5% when ultrasound features are concordant with benign cytology 1

Recommended Management Algorithm

Initial Approach

  • Measure TSH levels to assess thyroid function and rule out autonomous nodule 1

  • Perform high-resolution ultrasound to document baseline nodule characteristics and assess for any suspicious features that might be discordant with benign cytology 1

  • Review ultrasound for high-risk features including microcalcifications, marked hypoechogenicity, irregular/infiltrative margins, absence of peripheral halo, or central hypervascularity 1

Surveillance Protocol

  • Repeat ultrasound at 12-24 months to assess for interval growth or development of suspicious features 1

  • Monitor for compressive symptoms including dysphagia, dyspnea, or voice changes 1

  • Continue surveillance indefinitely if nodule remains stable and asymptomatic 1

Indications for Surgery (Despite Benign Cytology)

  • Compressive symptoms clearly attributable to the nodule (dysphagia, dyspnea, voice changes) 1

  • Cosmetic concerns that are significant and patient-driven 1

  • Large nodules >4 cm due to increased false-negative rate and higher risk of compressive symptoms 1

  • Discordance between benign cytology and highly suspicious ultrasound features (multiple high-risk features present) 1

Critical Pitfalls to Avoid

  • Do not override benign cytology based solely on nodule size unless the nodule is >4 cm or causing compressive symptoms 1

  • Do not perform molecular testing on Bethesda II nodules, as the pretest probability of malignancy is so low (1-3%) that molecular markers add minimal clinical value 1

  • Do not proceed to surgery for Bethesda II nodules without specific indications, as this leads to overdiagnosis and overtreatment of benign disease 1

  • Do not ignore worrisome clinical findings if present—false-negative results occur in up to 11-33% of cases when clinical suspicion is high 1

High-Risk Clinical Features That Would Modify Management

If any of the following are present, consider repeat FNA or closer surveillance despite benign cytology:

  • History of head and neck irradiation (increases malignancy risk 7-fold) 1

  • Family history of thyroid cancer, particularly medullary carcinoma or familial syndromes 1

  • Age <15 years or male gender (higher baseline malignancy probability) 1

  • Rapidly growing nodule over serial ultrasounds 1

  • Firm, fixed nodule on palpation suggesting extrathyroidal extension 1

  • Suspicious cervical lymphadenopathy on ultrasound 1

  • Vocal cord paralysis suggesting invasive disease 1

Role of Repeat FNA

  • Repeat FNA is generally not indicated for Bethesda II nodules unless there is significant interval growth (>20% increase in two dimensions with minimum 2mm increase) or development of new suspicious ultrasound features 1

  • If repeat FNA is performed due to discordant features, ensure ultrasound guidance to sample any suspicious solid components 1

References

1
Guideline

Ultrasound-Guided FNA Biopsy for Thyroid Nodules

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Related Questions

What is the diagnosis and management plan for a patient with a thyroid nodule showing abundant colloid admixed with honeycomb sheets, clusters, and single small, delicate follicular epithelial cells on Fine Needle Aspiration (FNA) results?
What is the appropriate monitoring for a follicular nodule in the thyroid gland?
What is the best initial diagnostic approach for a patient with a hard woody thyroid nodule, compression manifestations, history of hypothyroidism (underactive thyroid) episodes, and jaundice?
What is the best initial diagnostic step for a patient with a hard woody thyroid nodule, compression manifestations, history of hypothyroidism episodes, and jaundice?
What is the treatment for a thyroid cyst?
What is the renally adjusted dose of gabapentin (Neurontin) for an adult patient with Acute Kidney Injury (AKI) and impaired renal function, specifically with a creatinine clearance (CrCl) of less than 60 mL/min?
What is the best treatment approach for a male patient of reproductive age with varicocele?
What is the initial treatment for a patient with small vessel vasculitis?
Is it likely that a female of reproductive age with a history of three successful pregnancies with female offspring and one miscarriage, which occurred while attempting to conceive a male through gender swaying methods later in her menstrual cycle, was carrying a male fetus at the time of the miscarriage?
How does pneumoperitoneum (inflation of the abdominal cavity with gas, typically carbon dioxide (CO2)) cause ventilation-perfusion (V/Q) mismatch in a patient undergoing elective laparoscopic surgery?
Can hypertension cause tinnitus in patients with a history of high blood pressure?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question