Thyroid Nodule Evaluation and Management

Comprehensive practice flashcards covering the clinical evaluation, risk stratification, and management of thyroid nodules based on the 2015 ATA guidelines.

Thyroid nodules

Discrete lesions present within the thyroid gland that are radiologically distinct from the adjacent parenchyma.

Multiple endocrine neoplasia type 2 (MEN2)

A familial condition predisposing to thyroid malignancies specifically associated with medullary thyroid cancer.

Familial nonmedullary thyroid cancer (FNMTC)

A condition affecting two or more first-degree relatives that can occur in isolation or as part of syndromes like Cowden's or Gardner's syndrome.

Suppressed TSH level

An indicator of a hyperfunctioning nodule, which has an exceedingly small risk of malignancy ($7\%$ to $15\%$ in adults generally, but much lower if hyperfunctioning).

Serum thyroglobulin levels

Tests that are neither sensitive nor specific for the detection of thyroid cancer and should not be ordered in the evaluation of thyroid nodules.

Technetium-99m pertechnetate ($^{99m}Tc$)

The radionuclide imaging modality of choice in Australia for evaluating patients with a TSH level below the normal range.

Sonographic features with high specificity for cancer

Microcalcifications, irregular margins, and a taller than wide shape (greater anteroposterior diameter than transverse diameter).

High suspicion (ATA classification)

Solid hypoechoic nodules with a malignancy risk of $>70-90\%$, where FNA is recommended for nodules $\geq 1\,cm$.

Intermediate suspicion (ATA classification)

Solid hypoechoic nodules with smooth margins with a malignancy risk of $10-20\%$, where FNA is recommended for nodules $\geq 1\,cm$.

Low suspicion (ATA classification)

Solid isoechoic or hyperechoic solid nodules or partially cystic nodules with eccentric solid areas having a malignancy risk of $5-10\%$, where FNA is recommended for nodules $\geq 1.5\,cm$.

Very low suspicion (ATA classification)

Spongiform or partially cystic nodules with a malignancy risk of $<3\%$, where FNA is considered for nodules $\geq 2\,cm$.

Benign (ATA classification)

Cystic nodules with no solid component having a malignancy risk of $<1\%$, where FNA is not required.

The Bethesda system

A standardized cytopathology reporting system for thyroid nodules that provides malignancy risk estimates and recommended management plans.

Incidentaloma

A non-palpable, asymptomatic thyroid nodule detected via imaging (CT, MRI, or PET) that carries the same malignancy risk as a palpable nodule.

FDG-PET focal uptake

A finding associated with a $35\%$ risk of malignancy, requiring ultrasound-based FNA for all focal nodules $>1\,cm$.

Paediatric thyroid nodules

Nodules in children which have a malignancy rate of approximately $26\%$, compared to the $5\%$\text{--}$10\%$ rate seen in adults.

Bethesda Category 3 (AUS/FLUS)

Atypia of undetermined significance or follicular lesion of undetermined significance, associated with a $10-30\%$ malignancy risk.

High-volume thyroid surgeon

The recommended referral destination for any thyroid nodule biopsy result indicating malignancy or suspected malignancy.