What is the management plan for a 19x11x8mm well-defined hypoechoic solid nodule in the deep aspect of the midpole of the right thyroid lobe?

Management of 19×11×8mm Hypoechoic Solid Thyroid Nodule

This nodule requires ultrasound-guided fine-needle aspiration (FNA) biopsy based on its size (>1 cm) and solid hypoechoic composition, which are established high-risk features for malignancy. 1, 2

Rationale for FNA Recommendation

The combination of solid composition and hypoechoic appearance substantially increases malignancy risk and warrants tissue diagnosis. 1

• Solid composition carries higher malignancy risk compared to cystic nodules, making this a critical feature requiring evaluation 1
• Hypoechoic appearance is a well-established suspicious sonographic feature associated with increased cancer probability 1, 3
• Any thyroid nodule >1 cm should undergo FNA, and this 19mm nodule clearly exceeds this threshold 1, 2
• The nodule's size alone (approaching 2 cm) represents a worrisome feature associated with 3-times greater malignancy risk 1

Procedural Approach

The FNA must be performed under ultrasound guidance, as this is the gold standard method with superior accuracy, safety, and cost-effectiveness 1, 2

• Ultrasound guidance significantly reduces non-diagnostic samples compared to freehand technique 4
• FNA remains the most accurate and cost-effective method for preoperative diagnosis of thyroid malignancy 1
• The procedure should ideally have on-site cytology assessment to ensure sample adequacy 4

Risk Stratification Context

Additional clinical factors that would further increase urgency for FNA include:

• History of head and neck irradiation - lowers threshold for immediate biopsy 1
• Family history of thyroid cancer - particularly medullary carcinoma or familial syndromes 1
• Male gender or age <15 years - increases baseline malignancy probability 1
• Rapidly growing nodule - suggests aggressive biology 1
• Suspicious cervical lymphadenopathy - mandates immediate evaluation 1

Expected Cytology Results and Next Steps

The FNA will yield a Bethesda classification (Categories I-VI) that determines subsequent management:

• Bethesda II (Benign): Very low malignancy risk (1-3%), can proceed to surveillance with ultrasound monitoring 1
• Bethesda III/IV (Indeterminate): Consider molecular testing (BRAF, RAS, RET/PTC, PAX8/PPARγ) to guide surgical decision, as 97% of mutation-positive nodules are malignant 1
• Bethesda V/VI (Suspicious/Malignant): Immediate surgical referral for total or near-total thyroidectomy 1
• Bethesda I (Non-diagnostic): Repeat ultrasound-guided FNA; if persistently non-diagnostic, consider core needle biopsy 2, 5

Critical Pitfalls to Avoid

• Do not rely on thyroid function tests (TSH, T3, T4) for malignancy assessment, as most thyroid cancers present with normal thyroid function 1
• Do not refer for FNA without ultrasound capability - the procedure must be ultrasound-guided to meet current guideline standards 2
• Be aware that follicular neoplasms may yield indeterminate results requiring surgical excision for definitive diagnosis, as FNA cannot distinguish follicular adenoma from carcinoma 2
• Do not delay FNA based on absence of symptoms - most clinically significant thyroid cancers are asymptomatic at presentation 3

Additional Diagnostic Considerations

Consider measuring serum calcitonin as part of the diagnostic workup to screen for medullary thyroid cancer, which has higher sensitivity than FNA alone 1

The deep midpole location does not alter the recommendation for FNA, though it may require careful ultrasound guidance during the procedure to ensure adequate sampling 2