A 55-year-old woman from a sub-Himalayan region presents with a 10-year history of slowly progressive anterior neck swelling. She is clinically euthyroid. Ultrasound shows the structure marked **A** (heterogeneous multinodular thyroid) with bilateral diffuse enlargement and multiple nodules of varying sizes. A dominant 2.8 cm nodule in the right lobe is solid, hypoechoic, taller-than-wide, with microcalcifications and ill-defined margins, scoring ACR-TIRADS 5. Based on the sonographic features of the dominant nodule within this heterogeneous multinodular pattern, which of the following is the most appropriate next management step?
A. Fine-needle aspiration cytology (FNAC) of the dominant nodule followed by Bethesda classification
B. Thyroid function tests and observation with 6-monthly ultrasound surveillance
C. Levothyroxine suppression therapy to reduce TSH-driven nodular growth
D. Total thyroidectomy without cytological confirmation
Explanation
Why Fine-needle aspiration cytology (FNAC) of the dominant nodule followed by Bethesda classification is right
The dominant nodule within the heterogeneous multinodular thyroid (marked A) exhibits multiple high-risk sonographic features for malignancy: solid hypoechoic composition, taller-than-wide shape (anteroposterior > transverse), microcalcifications, and ill-defined margins — all hallmarks of papillary thyroid cancer. ACR-TIRADS 5 classification mandates FNAC for nodules ≥1 cm, and this 2.8 cm nodule clearly meets this threshold. Per ATA 2015 guidelines, high-suspicion sonographic patterns require FNAC regardless of patient euthyroid status. The Bethesda System provides standardized cytological reporting to guide definitive management (surgery for malignant/suspicious, observation for benign). This approach balances diagnostic accuracy with avoiding unnecessary surgery in a euthyroid patient with benign-appearing background parenchyma.
Why each distractor is wrong
Thyroid function tests and observation with 6-monthly ultrasound surveillance: While observation is appropriate for euthyroid asymptomatic MNG with benign features, this dominant nodule has ACR-TIRADS 5 (high-suspicion) features that mandate cytological evaluation before deferring intervention. Surveillance alone risks missing malignancy.
Levothyroxine suppression therapy to reduce TSH-driven nodular growth: Levothyroxine suppression is no longer routinely recommended in modern practice (ATA 2015 guidelines) due to limited efficacy and risks of atrial fibrillation and osteoporosis. It does not address the malignancy risk of the dominant nodule and would be inappropriate without first ruling out cancer via FNAC.
Total thyroidectomy without cytological confirmation: Surgery is definitive for confirmed malignancy or compressive disease, but performing total thyroidectomy without cytological confirmation in a euthyroid patient with a single suspicious nodule is overtreatment. FNAC results guide the extent and urgency of surgery.
High-YieldNEET PG
ACR-TIRADS 5 nodules ≥1 cm require FNAC; microcalcifications, taller-than-wide shape, and hypoechoic solid composition are red flags for papillary cancer in multinodular goiter.
ACR-TIRADS; ATA Thyroid Nodule Guidelines 2015
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